Citation
Insects and diseases of the pecan in Florida

Material Information

Title:
Insects and diseases of the pecan in Florida
Series Title:
Florida Agricultural Experiment Station bulletin no. 619
Creator:
Phillips, Arthur M.,
Large, John R. (John Runyon), 1901-
Cole, J. R. (John Rufus), 1900-
Affiliation:
Florida Agricultural Experiment Station
Place of Publication:
Gainesville, Fla.
Publisher:
Florida Agricultural Experiment Station, University of Florida
Publication Date:
Language:
English
Physical Description:
84 p. : ill. ; 23 cm.

Subjects

Subjects / Keywords:
Agriculture ( LCSH )
Farm life ( LCSH )
Farming ( LCSH )
University of Florida. ( LCSH )
Pecan -- Diseases and pests -- Florida ( LCSH )
Pecan -- Diseases and pests -- Control -- Florida ( LCSH )
Agriculture -- Florida ( LCSH )
Farm life -- Florida ( LCSH )
Spatial Coverage:
North America -- United States of America -- Florida

Notes

General Note:
"A revision of Bulletins 411 and 499"--T.p. ; "In cooperation with United States Department of Agriculture"-- T.p.
Funding:
Florida Historical Agriculture and Rural Life

Record Information

Source Institution:
Marston Science Library, George A. Smathers Libraries, University of Florida
Holding Location:
Florida Agricultural Experiment Station, Florida Cooperative Extension Service, Florida Department of Agriculture and Consumer Services, and the Engineering and Industrial Experiment Station; Institute for Food and Agricultural Services (IFAS), University of Florida
Rights Management:
All rights reserved, Board of Trustees of the University of Florida
Resource Identifier:
18302293 ( OCLC )
AEN7759 ( NOTIS )
027104328 ( ALEPH )

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HISTORIC NOTE


The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source
(EDIS)

site maintained by the Florida
Cooperative Extension Service.






Copyright 2005, Board of Trustees, University
of Florida








(A Revision of Bulletins 411 and 499)

UNIVERSITY OF FLORIDA
AGRICULTURAL EXPERIMENT STATIONS
J. R. BECKENBACH, Director
GAINESVILLE, FLORIDA
In Cooperation with United States Department of Agriculture





Insects and Diseases of the

Pecan in Florida


By
ARTHUR M. PHILLIPS, JOHN R. LARGE AND JOHN R. COLE


Fig. 1.-The foliage and large nuts have been attacked by scab;
the small pecans by nut casebearer.


Bulletin 619


January 1960








CONTENTS
Page
INSECTS OF THE PECAN ....................-----...... .... .. .......... .. 4
Insects Injuring the Nuts .. -- -4.... ................ ..... 4
Hickory Shuckworm ..............--- -- --.. ----- ---...... ... 4
Pecan Nut Casebearer ..........................--. ..-------- .... 6
Pecan W eevil .................................. ..--....--- ..... ...------- ..--- 10
Southern Green Stink Bug ......................- ..... ..... .. -----14
Spittlebug ......................... .......... ..... ........ 16
INSECTS INJURING THE FOLIAGE AND SHOOTS ..............................-..----- 17
Black Pecan Aphids ... .............. ... ...........----- ---------- 17
Y yellow Aphids ............-.....- .... ..... ...... ... ... 18
M ites .................. .....-- .......... ......-- ... .. 19
Fall W ebworm .................-- .....------- -.. --..----.. -...- 20
W alnut Caterpillar .................... ...............--.............. ...... 24
Pecan Bud M oth .. ...... ........ ...... .... .... ............. 25
Pecan Leaf Casebearer .........................-.........- .---...-------.... 28
Pecan Cigar Casebearer .....................................-----. --... ---.. --- 31
Pecan Nursery Casebearer ..................... ..--........ ..- ......- 31
Pecan Phylloxera --.. --...... .... ...... .... -- ........-...... ....... 32
Pecan Catocala ........... ..-- .....--- ----............ .... .. --- 35
M ay Beetles ................... ........-................. .... 36
Hickory Horned Devil ................................... ---------- 37
INSECTS INJURING THE TRUNK AND BRANCHES .--.....................--.--....---- 40
Twig Girdler .........- ......... ..-- .--. -- -----.. ...-.. .. ... .. 40
Flat-headed Apple Tree Borer ................................. -...... 41
Red-Shouldered Shot-Hole Borer .................... ..............---- 48
Term ites .......-- ......-... ...... ...... ....................... 44
DISEASES OF THE PECAN ....------------- --................... .. ..... ... .. 44
Diseases Due to Specific Organisms ........... ............-......... ....... 44
Scab ..............-----.-------. ---.....------.. 44
Downy Spot .................. ....- ....-- .. .... --------.---- 51
Pecan Leaf Blotch .-........................ -----..... .. ....... 52
Brown Leaf Spot ........ ................... .......----- ..... .. .. 53
Gnomonia Leaf Spot ........-...... ...- ........... ......... 54
N nursery Blight ......... ............................ .... 54
Thread Blight ...............................- -- .... ... .. ..... .. 56
Powdery Mildew .......-- -- .........-------- ..... 58
Pink M old ... ............. .... ........... .. .. ..... 60
Pink Mold-----------------------------
W ood Rot ...-- ...-.. .............. ----------... ..... ... ....... 60
Crown Gall .............................- ............... ... ..... ---------. --- ----. 61
DISEASES DUE TO NUTRITIONAL OR ENVIRONMENTAL FACTORS .................... 64
Rosette ..................--....---- --.--- ...-- .... -- -----..- ---. ----------... .... -. 64
Little Leaf ...........-...---- .....- ..--.-----. .- ---.-.... ....-- ---- -........... 70
Spanish M oss ...........................................................---- -..--. -- -- 70
Lichens ........----. ......-... --......-------.. -------..- 72
INJURIES DUE TO CLIMATIC CONDITIONS ....................... ..-- ...------------ 74
W inter Injury ............. ..... -----.. ...... .... .. ....... .-- 74
Sunscald .................-- --....- -- ---- ----.... ...... .. 75
Lightning Injury ............... ....... ........... ... .. ......---. 76
INSECTICIDES AND FUNGICIDES .........------.......-----.. -------- .. ......... 77
Preparation of Bordeaux Mixture ........----.......... ... ....-.... ...- .... 77
Ziram and Zineb ........................................ ...........--------- ........... 78
DDT, Parathion ................_--.. .......... ....... .---- -............ --... -.----. 78
Summer Oil Emulsions ..................................-----............. .... --- 78
Malathion, EPN, Guthion and Demeton .......................................... 79
N nicotine ........................ ....................... .... 79
Lim e-Sulfur ...... --............-... ......- ............------------......... ....------...... 79
Combined Sprays for Insects and Disease Control .......................... 80
Concentrate Spraying ..... .................. ......... .....--- ....... 80
The Hydraulic Spray Outfit ....................................... 80
Applying the Spray Material ............-- ... ................... .. 81
PRECAUTIONS .........-.............---.----- -- -----......------- ----... -------- 81
SPRAY PROGRAM FOR CONTROL OF PECAN INSECTS AND DISEASES ............ 84







Insects and Diseases of the

Pecan in Florida
ARTHUR M. PHILLIPS,1 JOHN R. LARGE2 and JOHN R. COLE 8

INTRODUCTION
Control of pecan insect pests and diseases is seldom easy.
In some situations and circumstances control is almost impos-
sible, even with the highly effective pesticides now available.
Pecan trees, Carya illinoensis Engel. & Graeben, often reach a
height of 60 feet or more, with a correspondingly wide spread
of branches. A powerful machine capable of delivering spray
at high pressure is needed to deliver the pesticide to the upper
portions of large trees. Many Floridians have a few pecan trees
about their homes and a large portion of the commercial pecan
orchards contain only a few acres. To all these persons the cost
of high power spray equipment is prohibitive and they must
use other methods of pest control.
Many varieties of pecans are now available and new ones
are occasionally being developed. Varieties differ in many ways,
including their response or relationship to diseases. Some va-
rieties are highly susceptible to certain diseases, while others
exhibit varying degrees of tolerance or resistance. Persons
planting new trees should keep these facts in mind and select
varieties that will be relatively free of trouble or that will yield
well in spite of attack by diseases. Trees which are constantly
ravaged by diseases can be topworked to more desirable varieties
and thus be made to produce better crops of nuts.
The information in the following pages is designed to help
pecan growers to understand their pest and disease problems
better and to enable them to use the most effective means of
control at their disposal. This is a revision of Bulletins 411 and
499. Much of the descriptive matter and most of the control
recommendations are based on work and experience of the au-
thors. However, they have also used other sources of informa-
tion, notably USDA Farmers' Bulletin 1829. Acknowledgment
is here made for such material and for USDA photographs used
in some of the illustrations.
SEntomologist, Entomology Research Division, Agricultural Research
Service, USDA and Florida Agricultural Experiment Station, Pecan Insect
and Disease Investigation Laboratory, Monticello, Florida.
2 Associate Pathologist, Florida Agricultural Experiment Station, Pecan
Insect and Disease Laboratory, Monticello, Florida.
Pathologist, Crops Research Division, Agricultural Research Service,
U. S. Department of Agriculture, Albany, Georgia.







Florida Agricultural Experiment Stations


INSECTS OF THE PECAN

A large number of insects attack the pecan. Some of these
injure the nuts, others the foliage and shoots, while others at-
tack only the trunk and branches. Insects discussed here are
listed under the type of major injury they cause. Damage
caused by a particular insect will vary from year to year in the
same area and major changes in the economic importance of an
insect may occur in a short span of years. A few insects cause
more than 1 type of injury on pecans. The nut casebearer is
considered primarily a nut infesting insect; however, the larvae
also feed on the buds and in the shoots in early spring. The
pecan budmoth is considered a bud and foliage feeder, though
during the fall the larvae feed and develop in the shucks similar
to the shuckworm.

INSECTS INJURING THE NUTS
HICKORY SHUCKWORM
The hickory shuckworm, Laspeyresia caryana (Fitch), also
called the pecan shuckworm, is one of the most generally preva-
lent insect pests of
S-the pecan. This in-
sect also feeds upon
various species of
hickory and the in-

often much more
severe. It is pri-
Smarily a nut infest-
ing pest but the lar-
vae often are found
feeding in phyllox-
Sera galls on pecan
in early spring. The
larvae or worms de-
stroy a few of the
developing nuts dur-
Fig. 2.-Larvae of the hickory shuckworm in ing n a
immature pecan nuts (enlarged). ing June but cause
most damage dur-
ing July and August, when the insect is capable of destroying
50 percent or more of the pecan crop in seasons when there is
a light set of nuts. Nuts punctured during midsummer drop







Florida Agricultural Experiment Stations


INSECTS OF THE PECAN

A large number of insects attack the pecan. Some of these
injure the nuts, others the foliage and shoots, while others at-
tack only the trunk and branches. Insects discussed here are
listed under the type of major injury they cause. Damage
caused by a particular insect will vary from year to year in the
same area and major changes in the economic importance of an
insect may occur in a short span of years. A few insects cause
more than 1 type of injury on pecans. The nut casebearer is
considered primarily a nut infesting insect; however, the larvae
also feed on the buds and in the shoots in early spring. The
pecan budmoth is considered a bud and foliage feeder, though
during the fall the larvae feed and develop in the shucks similar
to the shuckworm.

INSECTS INJURING THE NUTS
HICKORY SHUCKWORM
The hickory shuckworm, Laspeyresia caryana (Fitch), also
called the pecan shuckworm, is one of the most generally preva-
lent insect pests of
S-the pecan. This in-
sect also feeds upon
various species of
hickory and the in-

often much more
severe. It is pri-
Smarily a nut infest-
ing pest but the lar-
vae often are found
feeding in phyllox-
Sera galls on pecan
in early spring. The
larvae or worms de-
stroy a few of the
developing nuts dur-
Fig. 2.-Larvae of the hickory shuckworm in ing n a
immature pecan nuts (enlarged). ing June but cause
most damage dur-
ing July and August, when the insect is capable of destroying
50 percent or more of the pecan crop in seasons when there is
a light set of nuts. Nuts punctured during midsummer drop







Florida Agricultural Experiment Stations


INSECTS OF THE PECAN

A large number of insects attack the pecan. Some of these
injure the nuts, others the foliage and shoots, while others at-
tack only the trunk and branches. Insects discussed here are
listed under the type of major injury they cause. Damage
caused by a particular insect will vary from year to year in the
same area and major changes in the economic importance of an
insect may occur in a short span of years. A few insects cause
more than 1 type of injury on pecans. The nut casebearer is
considered primarily a nut infesting insect; however, the larvae
also feed on the buds and in the shoots in early spring. The
pecan budmoth is considered a bud and foliage feeder, though
during the fall the larvae feed and develop in the shucks similar
to the shuckworm.

INSECTS INJURING THE NUTS
HICKORY SHUCKWORM
The hickory shuckworm, Laspeyresia caryana (Fitch), also
called the pecan shuckworm, is one of the most generally preva-
lent insect pests of
S-the pecan. This in-
sect also feeds upon
various species of
hickory and the in-

often much more
severe. It is pri-
Smarily a nut infest-
ing pest but the lar-
vae often are found
feeding in phyllox-
Sera galls on pecan
in early spring. The
larvae or worms de-
stroy a few of the
developing nuts dur-
Fig. 2.-Larvae of the hickory shuckworm in ing n a
immature pecan nuts (enlarged). ing June but cause
most damage dur-
ing July and August, when the insect is capable of destroying
50 percent or more of the pecan crop in seasons when there is
a light set of nuts. Nuts punctured during midsummer drop







Insects and Diseases of the Pecan in Florida


from the trees and the larvae complete their development in
the interior of the immature nuts (Fig. 2). During September
and late fall, after the nut shells have hardened, the larvae mine
or tunnel the shucks (Fig. 3), and may prevent the kernels from
developing properly and delay maturity. At harvest, heavily
infested nuts have tight shucks and the shells are stained with
black marks.





















L pc nt (enlarged). I
Fig. 3.-Larvae of the hickory shuckworm in shuck of nearly mature
pecan nuts (enlarged).

There are sometimes as many as 4 or 5 generations of the
shuckworm in a year in Florida, with so much overlapping of
the different broods that it would be difficult to tell which brood
causes most damage to pecans. Moths of the spring brood de-
veloping from larvae that spend the winter in pecan and hickory
shucks may emerge as early as the middle of February. Peak
emergence of the spring brood is usually during the latter part
of March or April, and it seems to coincide with the development
of early species of hickory. Most of these moths die before the
pecan nuts have set. However, moths of this brood may con-
tinue to emerge from the old shucks throughout the entire sum-
mer.







Florida Agricultural Experiment Stations


The moths (Fig. 4) are very inconspicuous and rarely noticed
in the orchard. Eggs are deposited on the young nuts or leaves.
Upon hatching, the tiny larvae gnaw
their way into the green nuts. Until
S the shell hardens the larvae work in
the interior of the immature nuts and
cause them to drop. After the shells
have hardened the larvae tunnel in the
shucks, preventing the kernels from de-
veloping properly. Full-grown larvae
pass the winter in shucks on the ground

Control.-Three applications of ei-
ther 2 pounds EPN 25 percent wettable
powder or 2 pounds Guthion 25 per-
cent wettable powder per 100 gallons
spray will give a reduction of 75 per-
hickory shuckworm rest- cent or more of a heavy infestation of
ing on immature pecan. shuckworm at harvest. See precau-
tions relative to handling these insecti-
cides in back of bulletin. In northern Florida the first applica-
tion should be August 15 to 20, and additional applications at
2-week intervals. Even though these insecticides do not give
complete control, they are more effective and practical than san-
itation and cultural practices.
When the insecticide control measures recommended for
shuckworm cannot be followed, a high percentage of the larvae
that winter in old pecan shucks may be killed by gathering and
destroying the shucks at harvest. However, this is feasible
only when the nuts are harvested on sheets. Plowing the shucks
under about March 1, after the larvae have pupated, also will
help reduce shuckworm infestation during the summer. If a
grower has only a few trees, he should pick up the drops during
midsummer, remove them from the orchard and destroy them.

PECAN NUT CASEBEARER
The pecan nut casebearer, Acrobasis caryae Grote, is one of
the most serious insect pests attacking the pecan in Florida.
Its damage is especially serious during seasons when trees set
a light crop or on varieties which generally are not heavy pro-
ducers.








Insects and Diseases of the Pecan in Florida


These insects pass the winter as partly grown larvae in in-
conspicuous small cases, or hibernacula, which generally are
found where the buds join the stem (Fig. 5). The larvae be-
come active in the spring about the time the buds begin to open.
After feeding on the
buds for a short time,
the larvae bore into the
young, tender shoots
where they feed until full
grown. Then they trans-
form into the pupal
stage, mostly within the
tunnelled shoots.
In Florida the adults
or moths (Fig. 6 C)
emerge from the latter
part of April to May 20.
Peak emergence of this
generation usually co-
insides fairly well with a
the setting of the nuts.
The moth is small (meas-
uring only about 5/8 inch
across the expanded
wings) and a rather in- V
conspicuous dark-gray,
with a ridge or tuft of
long, dark scales extend- ,
ing across the fore wings
near the middle. The
moths lay their tiny,
greenish-w white eg gs
singly on the blossom
Fig. 5.--Hibernaculum or cocoon of the
end of the nut, and usu- pecan nut casebearer at base of a bud.
ally at or near the base
of the calyx lobes. Usually only 1 egg is laid in a cluster of nuts,
although occasionally 2 or more eggs may be found.
The greatest damage to the pecan crop is casued by the lar-
vae which develop from eggs laid by moths of the overwintering
generation, and occurs in May and early June. Soon after hatch-
ing the young larvae usually descend and feed for a short period
on the buds just below the cluster of nuts. Then they crawl back





Florida Agricultural Experiment Stations


up and attack the newly set nuts, usually entering them near
the stem end. Infested nuts are easily recognized by the char-
acteristic masses of borings, held together by fine silken threads
(Fig. 7) cast out by the larvae. A single larva of this genera-
tion may destroy several nuts or an entire cluster.


I


A


a


Fig. 6.-Larvae (A), Pupae (B) and Adults (C) of the pecan nut casebearer.
The larvae mature and pupate in the nuts (Fig. 8), and the
moths of the second generation appear from the middle of June
to the first of July. As a rule the larvae of the second genera-
tion cause much less damage than those of the first, because the





S /


/


Fig. 7.-Young nuts showing injury by larvae of the pecan nut casebearer.








,Insects and Diseases of the Pecan in Florida 9

nuts are larger and only 1 or 2 are necessary for the develop-
ment of an individual (Fig. 9).
























Fig. 8.-Pupae of the pecan nut casebearer within small nuts. Enlarged.





















Fig. 9.-Clusters of nuts infested by the second generation pecan
nut casebearer.







Florida Agricultural Experiment Stations


Larvae of later generations cause very little damage, as the
nuts are approaching maturity and the larvae feed on the outer
part of the shucks and the foliage instead of in the nuts them-
selves. The larvae can feed and develop entirely on foliage.
This explains to some extent why this insect survives in orch-
ards when there are no nuts on the trees.
Usually there are only 3 generations of this insect a year,
although sometimes there is a partial fourth generation in Flor-
ida. Larvae of the third generation that do not complete their
life cycle the first year and larvae of the fourth generation (if
there is 1) form the hibernacula or cases about the buds.
Control.-Since larvae of the first generation cause the most
damage, spraying when the nuts are small, or shortly after first
generation eggs begin to hatch, is the most effective method of
controlling the pecan nut casebearer. The period for spraying
varies with the season, locality and variety of pecans. As a
general rule, apply the spray when the tips of the small nuts
begin to turn brown. In Florida this is usually between May 1
and 20. Use either 2 pounds of 50 percent DDT wettable powder
in 100 gallons of water or 2 pounds 15 percent parathion wet-
table powder or 3 pounds 25 percent malathion wettable powder
in 100 gallons water. If a leaf scorch condition caused by mites
appears on DDT-sprayed trees, apply a miticide as recommended
for control of mites.
DDT, parathion or malathion may be used in combination
with either a 6-2-100 bordeaux mixture or 2 pounds ziram (76
percent) or 2 pounds zineb ('65 percent) as recommended in
fungicide spray schedule for control of scab or foliage diseases
and control the nut casebearer and scab with one spray applica-
tion.
PECAN WEEVIL
The pecan weevil, Curculio caryae (Horn), is a very destruc-
tive pest of pecans and hickories, though apparently it has been
of minor importance in Florida. It has caused heavy damage
to pecans in other Southern States for a number of years, but it
was not known to occur in this state prior to 1945. Since then
it has been found in several localities in Jefferson, Leon, Gads-
den, Jackson, Calhoun and Santa Rosa counties.
The weevil may spread rather slowly, as the adults usually
do not go far from the tree where they develop. When the
adults emerge from the soil, they tend to go to the nearest trees,






Insects and Diseases of the Pecan in Florida


and if there are nuts
feed and lay eggs.
The life history
of the weevil has not
been studied thor-
oughly in F 1 o r i d a,
but it is known that
the complete life cy-
cle requires 2 or 3
years. It is thought
that the adults (Fig.
10) begin to emerge
about the first of
July and continue to
appear through the
summer. The time
of egg laying depends
on the stage of de-
velopment of the pe-
can nuts, as eggs are
not laid until the nut


on the trees, the insects remain there to


Fig. 10.-Adult pecan weevils, male left, female
right, 21/2 times natural size.

kernels have hardened. This will vary


with the season, locality and variety of pecan. The female
weevil uses its long beak to make a puncture through the shuck
and shell of the nut, and then lays an egg in this opening. The
grubs or larvae (Fig. 11) hatching from the eggs feed on the
kernels and become fully grown in a few weeks. They then make
circular holes (Fig. 11) through
the side of the nuts. They
emerge through these holes,
drop to the ground and enter the
soil to a depth of 4 to 12 inches.
There they make earthen cells
in which they pupate. Pupa-
tion may occur that same fall or
may be delayed until the second
fall after they enter the soil.
The adult weevils emerge from
the soil during the summer fol-
lowing pupation. ,
The pecan weevil is respon- Fig. 11.-Grubs or larvae of the
sible for 2 distinct types of dam- pecan weevil within nut and emer-
gence holes where weevil grubs left
age. During July and August, nut.


i!







Florida Agricultural Experiment Stations


before the shells have hardened, the adult weevils make feed-
ing punctures in the nuts. These punctures cause the nuts to
drop and the entire crop may be destroyed if the weevils are
numerous and the crop is light. If there is a good crop on the
trees, this damage may not be noticed or may be attributed to
other causes.
The second type of damage is caused by the grubs in the
nuts. At harvest time the infested nuts may contain 1 or more
of the white, legless grubs, or if the grubs have already emerged
to pupate, there will be circular holes in the shells about 1/8 inch
across. Infested nuts are entirely worthless, as the grubs de-
stroy the kernels completely, and in addition the shucks may
stick tightly to the shells.
Pecan varieties differ widely in susceptibility to attack by
the weevil. Early maturing varieties generally are most heavily
infested. Most species of hickory nuts are infested in areas
where the weevil is found.
Control.-DDT is an effective insecticide for control of the
pecan weevil. Use 6 pounds of 50 percent DDT wettable powder,
or equivalent, per 100 gallons of water. If either bordeaux mix-
ture, ziram or zineb is used for control of pecan scab, the DDT
may be combined with the fourth and fifth fungicide applica-
tions. Toxaphene also will control the pecan weevil. Use 6
pounds of a 40 percent wettable powder, or equivalent, per 100
gallons spray. Do not use toxaphene with bordeaux mixture
but it can be used with ziram or zineb.
The insecticide application should correspond with the emerg-
ence of the adult weevils. This is the only way to prevent the
weevils from feeding and the nuts from dropping. The first
application should be made when 6 or more weevils are found
on any tree known to have been infested in previous years. The
second application should be 10 to 14 days later.
When an infested tree is jarred, the adult weevils drop to the
ground, where they lie motionless for a few minutes. Advantage
may be taken of this habit to determine when to begin the spray
applications. Place regular picking or harvesting sheets under
the tree to be examined for weevils. Then jar each limb lightly
2 or 3 times with a padded pole or climb the tree and jar the
limbs with the foot. When 6 or more weevils are jarred from
a tree, it is time to make the first insecticide application.
With only a few pecan trees, weevil damage may be reduced
about 50 percent by jarring the trees and collecting the weevils







Insects and Diseases of the Pecan in Florida


at weekly intervals during the period of adult activity, usually
from first of July to mid-September. It is a good policy to jar
only 1 or 2 trees which were heavily infested the previous year
until weevils begin to appear. During the succeeding weeks all
of the trees should be shaken. Regular harvesting sheets are
spread under the trees while they are jarred and the collected


/pi" rr
( A


Fig. 12.-Kernel spots on Schley pecan kernels caused by stinkbug
injury. The upper and central views show the location on the ridges and
edges of the kernels. The lower sections of kernels, cut through the spots,
show the depth and extent of the injury.


/, im







Florida Agricultural Experiment Stations


weevils may be killed by dropping them into a can containing a
little kerosene.
In weevil infested orchards harvest the pecans as early as
possible and take special care to gather all of the nuts, both
good and bad. Sort the nuts immediately and burn or otherwise
destroy all faulty ones to kill any remaining weevil grubs.

SOUTHERN GREEN STINKBUG
The Southern green stinkbug, Nezara viridula (L.), or
"pumpkin bug," and certain other plant-feeding bugs frequently
have caused serious damage to the pecan crop of individual grow-
ers in Florida. The feeding of these sucking insects produces
the trouble known to the pecan grower as "black pit" and causes
the nuts to drop prematurely if injured before the shells have
become hard. However, a similar condition is caused by the
hickory shuckworm. During the midsummer drop it may be
difficult for the grower to tell whether the drop was caused by
the work of the shuckworm or the sucking bugs.
After the nuts have passed the water stage and the shells
have become hard, the puncture or injury by the stinkbug pro-
duces a condition known as kernel spot (Fig. 12) instead of black
pit. The spots on the kernel are decidedly bitter and this injury
cannot be detected until the kernel has been removed from the
shell.
The adult, stinkbug is shield-shaped (Fig. 13). It passes the
winter in the adult stage and often is active during periods of
mild weather. The eggs may be found in clusters on the under
sides of leaves of host plants from April to November. This bug
begins feeding on the nuts about the time they reach the water
stage and continues until the nuts are practically mature. There
may be as many as 4 generations in a year.
SThe Southern green stinkbug attacks a large number of
plants, both wild and cultivated, which serve as food for the
young or "nymphs" until they reach the adult stage. Pecan
nuts are attacked only by the adult bugs, which fly to the trees
from plants on which they feed as nymphs.
Control.-Due to the feeding habits of the Southern green
stinkbug, it is difficult to control this insect on pecans with in-
secticides. Two pounds of parathion 15 percent wettable pow-
der or EPN and Guthion as applied for control of shuckworm
will give effective control. The parathion may be used alone
or in combination with the fungicide applied for control of scab.







Insects and Diseases of the Pecan in Florida


The black pit and kernel spot of pecans caused by the green
stinkbug and other plant bugs can be largely prevented by de-
stroying host plants in and near pecan orchards. Where the
stinkbugs are a serious problem, such crops as cowpeas, soy-
beans, beans, squash, tomatoes and Crotalaria mucronata Desv.
(Formerly C. striata DC.) should not be planted in or near the
orchard, and the orchard should be disked 2 or 3 times during
the summer to destroy native food plants.




































Fig. 13.-Southern green stinkbug feeding on pecan nuts.








Florida Agricultural Experiment Stations


SPITTLEBUG
The spittleburg, Clastoptera achatina Germ., is very common
on pecans in northern Florida during the early spring and sum-
mer and the presence of the froth-like material about the buds
(Fig. 14) or young pecans often causes concern to growers. Each
mass of spittle contains from 1 to a few immature insects. This
white substance probably protects the young or nymphs from
parasites and other insect enemies. The adult spittlebugs, com-
monly called frog-hoppers, usually are found wandering around
on shrubs and trees.
Control.-Where the spittlebugs are abundant and control
is desired, 2 pounds parathion 15 percent wettable powder per


Fig. 14.-Pecan twig showing spittle


'V 0


e-like substance produced by spittlebug.







Insects and Diseases of the Pecan in Florida


100 gallons water applied in the middle of May will control this
insect. The parathion may be added to the second application
of fungicide spray used for control of scab.

INSECTS INJURING THE FOLIAGE AND SHOOTS
BLACK PECAN APHID
The black pecan aphid, Melanocallis caryaefoliae (Davis),
may cause considerable premature defoliation when heavy infes-
tations develop on pe- r
can trees. This aphid
usually is more prev-
alent on trees that
have received a num-
ber of applications of
bordeaux mixture,
but unsprayed trees
may become heavily
infested. The injury
usually is most
noticeable during
August and Sep-
tember. First signs
of its presence are
more or less rectang-
ular, bright yellow
spots which appear
on the leaflets around
the feeding punc-
tures. These turn
brown (Fig. 15) and
the leaflets may drop
prematurely. Heavy
premature defolia-
tion has a direct ef-
fect on the quality
of the current pecan
crop and production
the following year.
The insect passes
the winter in the egg
Fig. 15.-Pecan leaflet injured by the black
stage in the crevices pecan aphid.







Insects and Diseases of the Pecan in Florida


100 gallons water applied in the middle of May will control this
insect. The parathion may be added to the second application
of fungicide spray used for control of scab.

INSECTS INJURING THE FOLIAGE AND SHOOTS
BLACK PECAN APHID
The black pecan aphid, Melanocallis caryaefoliae (Davis),
may cause considerable premature defoliation when heavy infes-
tations develop on pe- r
can trees. This aphid
usually is more prev-
alent on trees that
have received a num-
ber of applications of
bordeaux mixture,
but unsprayed trees
may become heavily
infested. The injury
usually is most
noticeable during
August and Sep-
tember. First signs
of its presence are
more or less rectang-
ular, bright yellow
spots which appear
on the leaflets around
the feeding punc-
tures. These turn
brown (Fig. 15) and
the leaflets may drop
prematurely. Heavy
premature defolia-
tion has a direct ef-
fect on the quality
of the current pecan
crop and production
the following year.
The insect passes
the winter in the egg
Fig. 15.-Pecan leaflet injured by the black
stage in the crevices pecan aphid.







Florida Agricultural Experiment Stations


of the bark. The eggs hatch in the spring and the young aphids
at first are pale green, but as they feed they turn a darker green
and the adults have a series of large black tubercles or spots on
the back and sides. The adults are very active. These aphids are
not found in crowded colonies. They feed on both sides of the
leaves and seem to prefer the shaded inner parts of the trees.
There may be as many as 15 generations of females during the
season and all except the last generation produce living young.
With the approach of cold weather the insect lays eggs for the
overwintering generation.
Control.-The black pecan aphid can be effectively controlled
by thorough spraying with either 2 pounds parathion 15 percent
wettable powder or equivalent, 3 pounds malathion 25 percent
wettable powder or equivalent, or demeton 25 percent emulsion
concentrate 1 pint per 100 gallons of water. These materials
may also be used in combination with either bordeaux mixture,
ziram or zineb as used to control pecan scab. Where serious
aphid injury has been experienced, make the first application
soon after the first yellow spots appear on the leaves. Repeat
applications as needed.
YELLOW APHIDS
Three species of yellow aphids-the yellow hickory aphid,
Monellia caryella (Fitch), M. nigropuncta Granovsky and the
black-margined aphid, M. costalis (Fitch)-attack the pecan.
These insects often occur in large numbers on the under side of
the leaves. Even when they are exceedingly numerous, they
do not cause any observable direct injury to pecans. However,
they excrete large quantities of honeydew on the leaves, which
supports the growth of a black fungus that makes the foliage
unsightly and interferes to some extent with the functioning of
the leaves. It is also known that this sticky excretion, or honey-
dew, supports the growth of scab spores.
The yellow aphids have the same number of forms and prac-
tically the same life history as the black pecan aphid and live
through the summer and winter in the same manner.
Control.-Predacious insects, parasites and entomogenous
fungi reduce the number of aphids enormously. Weather condi-
tions also influence their abundance. They tend to increase in
number during hot, dry spells and decrease when cold, wet
weather prevails.







Insects and Diseases of the Pecan in Florida


If yellow aphids become abundant and control measures are
necessary, use the same measures suggested for the black pecan
aphid.
MITES
The mite, Tetranychus hicoriae (McGregor), caused serious
injury to pecan foliage and premature defoliation in orchards
near Monticello, Florida, in June 1947. Since that time it has
been reported as causing injury to pecan foliage in almost every
section of the pecan-growing area of the state. This mite has
also been reported causing serious injury to pecan foliage in
other Southern States. It was also collected in 1948 near Mari-
anna, Florida, on water hickory, Carya aquatic Michx f. Nutt.
Observations indicate that the life history of this mite is
very similar to that of the common 2-spotted spider mite, Te-
tranychus telarius (L.). It is possible that damage to pecan fo-
liage attributed to the 2-spotted spider mite in the past was
actually caused by the new species.
An infestation generally starts on the lower branches of the
pecan tree and spreads upward. The feeding of large numbers
of these mites causes a characteristic type of foliage injury
(Fig. 16). The infested leaflets first show a light-brown discol-
oration along the midrib, where the mites start to feed. As
the mites and injury increase on the leaflet, the discoloration
spreads outward and the leaflet looks as if it had been scorched
by fire. Severely injured leaflets drop off and excessive prema-
ture defoliation may occur. Since this mite has the ability
under favorable conditions to increase its numbers rapidly to a
level that will result in severe defoliation of pecan trees, grow-
ers should be familiar with the type of injury and know when
to apply control measures.
Observations have indicated that the use of DDT for control
of the nut casebearer and other pecan insects has caused abnor-
mal increases in mite population. However, severe infestation
of mites may appear on unsprayed foliage.
Control.-Parathion, malathion or demeton is very effective
against mites present at time of application and possibly against
newly hatched crawlers for 3 to 4 days. The insecticides do not
kill the eggs and the population can build up rapidly from mites
that hatch several days after spraying if only a single spray
application is made. Use 2 pounds of 15 percent parathion wet-
table powder or equivalent, or 3 pounds malathion 25 percent








Florida Agricultural Experiment Stations


wettable powder or equivalent, or 1 pint demeton 25 percent
emulsifiable concentrate per 100 gallons water, or in combina-
tion with either bordeaux mixture or ziram applied for scab
control. Make first application when leaf scorch condition caused
by mite injury appears on foliage. Repeat application in 6 to
8 days.


Fig. 16.-Pecan leaves showing mite injury.

FALL WEBWORM
The fall webworm, Hyphantria cunea (Drury), is perhaps
the most conspicuous pecan insect, as the larvae form the fa-
miliar and unsightly webs over the twigs and foliage (Fig. 17).
The adult moth is about 1 inch across when the wings are spread,
usually pure white but sometimes with black or brown spots on
the wings. The eggs are deposited in masses on the leaves and
hatch in about a week. The larvae feed in colonies on the leaves
within the web (Fig. 18). When they need additional food, the
web is enlarged. When full grown, the larvae are more than
1 inch long and covered with white and black hairs.
In Florida the webworm has 2 broods a year. Moths of the
first brood appear in April and May, the second during the mid-
dle of summer. Larvae of the second brood feed during sum-








Insects and Diseases of the Pecan in Florida


Fig. 17.-Young pecan tree defoliated by fall webworm.


F


," )


r








Florida Agricultural Experiment Stations


mer and fall. The webworm passes the winter in the pupal stage
in cocoons under loose rubbish on the ground or just below the
surface of the soil.
Control.-Spraying with either 2 pounds 50 percent DDT wet-
table powder or 2 pounds 15 percent parathion wettable powder
per 100 gallons water, or in combination with bordeaux mixture,
zineb or ziram used for scab control, will give effective control
of this insect. EPN and Guthion as recommended for control of


Fig. 18.-Web and caterpillars of the fall webworm.






Insects and Diseases of the Pecan in Florida


Fig. 19.-Colony of walnut caterpillars on pecan shoot.


;1








Florida Agricultural Experiment Stations


shuckworm also gives excellent control of fall webworm. In
severe infestations it may be necessary to make 2 applications
of spray material, 1 for each brood. When the insects are not
abundant, they may be controlled by destroying the webs with
the larvae in them. The webs may be removed from the trees
with a long bamboo pole or long-handled tree pruner.

WALNUT CATERPILLAR
In Florida the walnut caterpillar, Datana integerrima G. & R.,
is a major pest during some seasons.
There are 2 gen-
erations of this in-
sect in Florida. The
moths from the over-
wintering pupae
emerge from the
ground from the mid-
dle of April to mid-
July. The eggs are
laid in masses on the
under sides of leaflets
and hatch in about a
week. The larvae
feed in colonies but
do not form a web
over the leaves (Fig.
19). When molting,
the larvae crawl to
the trunk or larger
-I limbs (Fig. 20),
where each sheds its
Skin. After molting
they return to the
upper branches and
continue e feeding.
The caterpillars feed
for 25 days or longer
Fig. 20.-Larvae of walnut caterpillar prior to and when full grown
molting on trunk of pecan tree.
they crawl down and
enter the soil to pupate. Development of the second brood is
similar to that of the first and late in the fall the larvae enter
the soil, where they pass the winter as pupae.







Insects and Diseases of the Pecan in Florida


Control.-The same spray treatment should be used as for
control of the fall webworm, or the colonies of caterpillars may
be removed from the trees and destroyed by crushing or burn-
ing. They are easily destroyed when found massed on the tree
trunks in the act of molting.

PECAN BUDMOTH
The pecan budmoth, Gretchena bolliana (Sling.), often
causes considerable damage to pecan nursery stock. The larvae
feed on and in the terminal buds of the young trees, causing ex-
cessive branching and stunted growth. During the past this
insect has been considered primarily a bud feeder, causing very
little damage in bearing orchards. However, as early as 1945
pecan shucks were found infested with budmoth larvae4, causing
damage similar to that of the shuckworm (Fig. 21). In north
Florida at harvest pecan shucks are commonly infested by pecan
budmoth larvae.














Fig. 21.-Larvae and pupae of the pecan budmoth in pecan shucks.

In June 1958 the pecan budmoth larvae caused heavy defoli-
ation on large pecan trees (Fig. 22) in the area around Climax,
Georgia, and extending south into Gadsden County, Florida. The
larvae pupated under the bark on the trees (Fig. 23) and some
trees defoliated in June suffered severe damage later in the sum-
mer when they were attacked by a later generation of this in-
sect. The pecan budmoth could become a major pest of the pecan
in this area.

Phillips, A. M. An Unusual Habit of the Pecan Budmoth in Florida.
Scientific Note, Jour. Econ. Ent. 38(5): 620. 1945.








26 Florida Agricultural Experiment Stations

This insect passes the winter as a moth, which is gray with
blackish-brown patches and about 2/3 inch across the expanded
wings. When the buds begin to open, the overwintered moths
lay eggs on the twigs near the buds. Moths of later generations
lay eggs on the leaves. There are probably 5 or 6 generations
in 1 season.
Control.-Young nursery trees should be kept in a vigorous
growing condition by proper cultivation and fertilization. Vig-


k






^. -
H-~ J *"


Fig. 22.-Large pecan trees defoliated by the larvae of the pecan budmoth.







Insects and Diseases of the Pecan in Florida


orously growing trees unfold their buds rapidly and this helps
to minimize the damage caused by the larvae.
Spraying with either 2 pounds DDT 50 percent wettable
powder or 2 pounds malathion 25 percent wettable powder per
100 gallons water or in combination with bordeaux mixture or
ziram as used for control of nursery blight will help to keep the
insect under control. A 2 percent parathion dust applied by


Fig. 23.-Pupae and pupae cases of pecan budmoth on pecan tree where
rough bark was removed.







Florida Agricultural Experiment Stations


aeroplane at rate of 20 pounds per acre also gave excellent coin-
trol of budmoth on young nursery trees. Four or 5 applications
of either spray or dust should be made at 2- to 3-week intervals.
The same spray schedule
recommended for bud-
moth control on young
pecan trees in the
Nursery should be effec-
tive also for control of
this insect on bearing
< trees.

|i PECAN LEAF
CASEBEARER
The pecan leaf case-
bearer, Acrobasis jug-
landis (LeB.), is also
considered a serious pest
of the pecan in Florida.
It causes most damage
after the larvae emerge
from their overwinter-
ing cases in early spring
when they feed on the
unfolding buds and
leaves (Fig. 24). In se-
S vere infestations pecan
Streets may be kept in a
semi-defoliated condition
for 3 or 4 weeks (Fig.
25). This injury often
reduces the nut crop, and
trees deprived of their
foliage in this manner
may be weakened mate-
rially.
These insects pass
the winter as larvae in
small cases or hibernac-
S ula about the buds, sim-
Fig. 24.-Injury to young buds in spring ilar to those constructed
caused by larvae of the pecan leaf case-
bearer. by the pecan nut case-







Insects and Diseases of the Pecan in Florida


bearer. After completing their development, they transform to
pupae within their cases. The moths usually appear from about
the middle of May until the first of August. The moth measures
only about % inch across the expanded wings, and generally is
grayish-brown. The adults are usually found hiding in debris


Fig. 25.-Pecan tree partially defoliated by larvae of the pecan leaf
casebearer in early spring.

at the base of the trees or in the thick foliage. There is only 1
generation a year.
The moths deposit their eggs on the under sides of the leaves
along a vein or near the junction of a vein with the midrib. The







Florida Agricultural Experiment Stations


young larvae may be found in their summer feeding cases (Fig.
26) on the under sides of the leaves from the middle of May until
November. The larvae feed very sparingly during the summer,
and rarely are longer
than 1/16 inch by
. fall. During the lat-
,I ter part of August
or in early Septem-
ber the partly grown
larvae start migrat-
ing from their sum-
mer feeding cases on
the leaves and form
their overwintering
cases around the
buds. Observations
indicate that there
is a very close rela-
tionship between the
falling of the leaves
and the migration of
the leaf casebearer
larvae, so the migra-
tion period varies,
depending on the va-
S, riety of pecans and
the season.
S, Control. DDT,
parathion and mala-
thion, when applied
for control of the nut
casebearer, will also
S. .. control the leaf case-
bearer. If it is not
:- necessary to spray
for control of the nut
-. casebearer, the leaf
Fig. 26.-Feeding cases of young leaf case- casebearer c a n be
bearer larvae (enlarged).
controlled by spray-
ing the trees in late June or early July with either 2 pounds of
DDT 50 percent wettable powder or 2 pounds of parathion 15
percent wettable powder or 3 pounds 25 percent malathion wet-







Insects and Diseases of the Pecan in Florida


table powder in 100 gallons water. On pecan varieties that have
scab, the insecticides may be combined with the fungicide in the
third or fourth application of the spray schedule (Page 84).
Only 1 application is necessary, if the under sides of the leaves
are well covered.

PECAN CIGAR CASEBEARER
The pecan cigar casebearer, Coleophora caryaefoliella Clem.,
although usually considered a minor pest, sometimes causes se-
rious damage to pecans,
especially in the western
part of the state. This
insect passes the winter
as a partly grown larva
in a light-brown case re-
sembling a miniature
cigar, usually attached
to twigs and limbs (Fig.
27). The larvae become
active in the spring about
the time the buds open
and feed on the buds and
foliage (Fig. 28) until
about the middle of May.
The adults appear dur-
ing the latter part of "
May and first of June
and lay their eggs on the
leaves. There may be
several generations dur- A
ing the season. 0 4w:
Control. If this Fig. 27.-Winter cases of the pecan cigar
casebearer at the base of the bud. Enlarged.
casebearer requires con-
trol measures, spraying in the spring with either DDT, para-
thion or malathion as recommended for nut casebearer or leaf
casebearer will give effective control.

PECAN NURSERY CASEBEARER
The pecan nursery casebearer, Acrobasis caryivorella Rago-
not, is found chiefly on pecan nursery stock, and in northern
Florida it causes considerable damage in nurseries. The feed-







Insects and Diseases of the Pecan in Florida


table powder in 100 gallons water. On pecan varieties that have
scab, the insecticides may be combined with the fungicide in the
third or fourth application of the spray schedule (Page 84).
Only 1 application is necessary, if the under sides of the leaves
are well covered.

PECAN CIGAR CASEBEARER
The pecan cigar casebearer, Coleophora caryaefoliella Clem.,
although usually considered a minor pest, sometimes causes se-
rious damage to pecans,
especially in the western
part of the state. This
insect passes the winter
as a partly grown larva
in a light-brown case re-
sembling a miniature
cigar, usually attached
to twigs and limbs (Fig.
27). The larvae become
active in the spring about
the time the buds open
and feed on the buds and
foliage (Fig. 28) until
about the middle of May.
The adults appear dur-
ing the latter part of "
May and first of June
and lay their eggs on the
leaves. There may be
several generations dur- A
ing the season. 0 4w:
Control. If this Fig. 27.-Winter cases of the pecan cigar
casebearer at the base of the bud. Enlarged.
casebearer requires con-
trol measures, spraying in the spring with either DDT, para-
thion or malathion as recommended for nut casebearer or leaf
casebearer will give effective control.

PECAN NURSERY CASEBEARER
The pecan nursery casebearer, Acrobasis caryivorella Rago-
not, is found chiefly on pecan nursery stock, and in northern
Florida it causes considerable damage in nurseries. The feed-







Florida Agricultural Experiment Stations


ing on and in the buds of the young trees is very similar to that
of the pecan budmoth. This casebearer also feeds on the foli-
age of bearing trees but, like the budmoth, causes very little
damage to such trees.
Like the other casebearers, these insects pass the winter as
partly grown larvae in hibernacula. However, the overwintering
larvae and hibernac-
ula are more than
twice the size of
those of either the
nut casebearer or leaf
casebearer. In t h e
nursery the larvae
emerge in the early
spring and feed in
the buds and on the
leaves until full
grown, when they
pupate in cocoons on
the leaves folded up
in the top of the
young nursery tree
(Fig. 30). The moths
are dark grayish
with some light spots
on the wings (Fig.
29-C). They are
much larger than
those of the nut case-
bearer or leaf case-
bearer. There are
probably 3 or 4 gen-
erations in 1 season.
Control. T he
Fig. 28.-Pecan leaflets injured by larvae of
the pecan cigar casebearer. same nursery prac-
tices and control
measures recommended for the pecan budmoth should control
this casebearer.
PECAN PHYLLOXERA
The injury caused by the pecan phylloxera, Phylloxera devas-
tatrix Perg., and the pecan leaf phylloxera, P. notabilis Perg.,





Insects and Diseases of the Pecan in Florida


I
B


4


Fig. 29.-(A) Larvae, (B) pupae and (C) adults of pecan nursery casebearer.
usually is not very serious in Florida, although sometimes it is
very conspicuous. The galls or tumor-like swelling caused by
the former species are found on the leaves, leaf-stalks, succulent
shoots or nuts of the current season's growth (Fig. 31). The
galls caused by the latter species are found only on the leaves
(Fig. 32). These insects attack either seedling or improved
Fig. 30.-Buds and foliage of young pecan trees injured by larvae of
pecan nursery cas-bearer.


A'








34 Florida Agricultural Experiment Stations


Fig. 31.-Galls of phylloxera on pecan shoot and leaves.


ILL







Insects and Diseases of the Pecan in Florida


varieties of the pecan and various species of hickory. The phyl-
loxera which cause these galls are very small insects closely
related to the aphids or plant lice.
These insects pass the winter in the egg stage in protected
places on the branches. The young appear in the early spring,
about the time the
buds unfold, and in-
sert their beaks into
the new growth. Their
feeding seems to stim-
ulate the growth of a
gall which soon covers
the insect. The insect
develops in the gall,
lays a large number of
eggs and then dies.
When the nymphs that
hatch from the eggs
develop into a d u 1 t s,
the gall splits open and
releases them.
Control.-A spray
mixture containing 13
fluid ounces of nico-
tine sulfate to 100 gal-
lons of water, with the
addition of 21/2 gal-
lons of liquid lime-sul-
fur for control of
h e a v y infestations, Fig. 32.-Galls of the pecan leaf phylloxera
on pecan leaves.
has been used success-
fully against this insect. For light to moderate infestations the
13 ounces of nicotine plus 2 quarts of summer oil emulsion or 3
pounds malathion 25 percent wettable powder per 100 gallons
of water is effective. These sprays should be applied during the
late dormant period, just as the buds begin to swell.

PECAN CATOCALA
Several species of catocala may destroy pecan foliage in the
spring. When abundant, these caterpillars are capable of do-
ing considerable damage by stripping the leaves until only the







Florida Agricultural Experiment Stations


petioles and stems remain. The caterpillar (Fig. 33) of Catocala
maestosa Hlst. is dark gray and when full grown may be more
than 3 inches in length. They hide by day in the crevices of
the bark. Their color so closely resembles that of the bark that
they often escape observation. Due to the size and leathery-
looking skin of these caterpillars, they are often called "alligator
worms."
These insects pass the winter in the egg stage on the under
side of the bark scales.
The eggs hatch in the
spring and the cater-
pillars feed on the fo-
liage d u r i n g spring
and early summer.
The moths (Fig. 34)
appear as early as the
latter part of June and
may continue to
emerge until late fall.
Control. Insecti-
cides applied for con-
trol of either the first
generation nut case-
bearer or the leaf case-
bearer in May will also
control the caterpil-
lars of the pecan cato-
cala. If these insects
become abundant
enough to require spe-
Fig. 33.-Full-grown larva of Catocala maes- cial control measures,
tosa, about % natural size. apply either DDT or
parathion as recommended for nut casebearer control.

MAY BEETLES
May beetles, Phyllophaga spp. and Anomala spp., also com-
monly called June bugs, are leaf-feeding insects which may cause
serious defoliation of young pecan trees in early spring. Trees
near grass or other uncultivated land usually are injured most.
The adults feed only at night.








Insects and Diseases of the Pecan in Florida


The adult beetles (Fig. 35) are robust, brown, and vary in
size. The larvae are the well-known white grubs that feed in
the soil upon the roots of plants, especially grasses. Two or
more years usually are required for larval development.
Control.-The beetles may be
removed from small trees at
night by collecting them and
dropping them into kerosene or
by jarring them onto a sheet on
the ground and then destroying
them.
Either 2 pounds DDT 50 per-
cent wettable powder or 2
nd p thn p e r c e n t Fig. 34.-Adult of Catocala maes-
pounds parathion 15 p percent tosa, about 1/2 natural size.
wettable powder per 100 gallons
water, applied early in the period of flight, will control the
beetles.
HICKORY HORNED DEVIL (REGAL MOTH)
Although the hickory horned devil, Citheronia regalis (F.),
is a very minor pecan pest, many inquiries are received concern-
ing it. This large caterpillar (Fig. 36) is the larva of the regal
moth, the largest and most magnificent of the royal moths (Fig.
37). The fore wings of the moth are olive, spotted with yellow,
and the hind wings are orange red, spotted with yellow.



I -- `










Fig. 35.-Adult May beetles (about 11 times natural size).

The larva is our largest caterpillar and can be recognized
easily by the large spiny horns with which it is armed. It feeds
on various trees and shrubs, but never becomes very numerous.








38









1


Florida Agricultural Experiment Stations


b


L ^ .- '
L .
Fig. 36.-Larva of the regal moth, commonly called "hickory horned devil."


[


Fig. 37.-Adult of the regal moth (male).


;;~"J~~


t-ddw-l







Insects and Diseases of the Pecan in Florida


Control.-Control measures are rarely required for this in-
sect on pecans. When the larvae are found, they may be re-
moved by hand and destroyed. In spite of their appearance,
they will not harm anyone handling them. If necessary, DDT
or parathion may be applied when the larvae are small as for
control of the fall webworm.


Fig. 38.-Twigs cut off of a single tree by the twig girdler.








Florida Agricultural Experiment Stations


INSECTS INJURING THE TRUNK AND BRANCHES
TWIG GIRDLER
The twig girdler, Oncideres cingulata (Say), is probably
more familiar to growers than any other pecan insect, because
of its habit of cutting off the twigs during the late summer and
fall. When the girdlers are abundant, they may cause serious
damage. Large numbers of twigs have been counted under a
single tree and many of the twigs had clusters of immature
nuts attached (Fig. 38). The severing of so many twigs also


Fig. 39.


-Adult, or beetle, of the twig girdler at work on a persimmon
branch. Girdler more than twice natural size.


greatly reduces the fruiting area of the tree for the following
year or more. Pecan nurseries also may suffer heavy losses if
adjacent to heavily infested areas. The twig girdler attacks a
large number of trees and shrubs, including Australian pine,
Casuarina spp., hackberry and cajuput tree, but it is especially
bad on pecan, hickory and persimmon.
Adult beetles (Fig. 39) range from 1/~ to 5/v inch, and are
grayish brown and rather inconspicuous on the trees, owing to
this coloring. The beetles appear in pecan orchards the latter
part of August. Twigs are girdled to provide proper conditions








Florida Agricultural Experiment Stations


INSECTS INJURING THE TRUNK AND BRANCHES
TWIG GIRDLER
The twig girdler, Oncideres cingulata (Say), is probably
more familiar to growers than any other pecan insect, because
of its habit of cutting off the twigs during the late summer and
fall. When the girdlers are abundant, they may cause serious
damage. Large numbers of twigs have been counted under a
single tree and many of the twigs had clusters of immature
nuts attached (Fig. 38). The severing of so many twigs also


Fig. 39.


-Adult, or beetle, of the twig girdler at work on a persimmon
branch. Girdler more than twice natural size.


greatly reduces the fruiting area of the tree for the following
year or more. Pecan nurseries also may suffer heavy losses if
adjacent to heavily infested areas. The twig girdler attacks a
large number of trees and shrubs, including Australian pine,
Casuarina spp., hackberry and cajuput tree, but it is especially
bad on pecan, hickory and persimmon.
Adult beetles (Fig. 39) range from 1/~ to 5/v inch, and are
grayish brown and rather inconspicuous on the trees, owing to
this coloring. The beetles appear in pecan orchards the latter
part of August. Twigs are girdled to provide proper conditions







Insects and Diseases of the Pecan in Florida


for the development of the larvae, which are unable to subsist
on wood containing sap. The eggs are always deposited in the
severed portion of the twig. They hatch in about 3 weeks but
the larvae grow very little during fall and winter. In the spring
the larvae grow rapidly and complete their transformation to
adult beetles in the twigs by the latter part of August.
Control.-Use either 4 pounds 50 percent DDT wettable
powder or 3 pounds 15 percent parathion wettable powder per
100 gallons water. Make first application last week in August
and follow with 2 more applications at 2- or 3-week intervals.
EPN and Guthion applied for control of shuckworm also give
effective control of the twig girdler during that period.
A simple method for controlling the twig girdler is to gather
and burn the severed branches during fall and winter. Take
special care to collect all branches on the ground as well as those
lodged in the trees. If there are hickory or persimmon trees
adjacent to the pecan orchard, destroy the severed branches
from these also.

FLATHEADED APPLE TREE BORER
The flatheaded apple tree borer, Chrysobothris femorata
(Oliv.), attacks many kinds of deciduous trees as well as the
pecan. The injury results from the tunnelling of the borer grubs
in the bark and sapwood of the trunk and larger branches (Fig.
40). Generally previously weakened trees suffer most from this
insect, although vigorously growing trees sometimes become in-
fested. Trees that have been injured in cultivation or affected
by sunscald and winter injury are usually very susceptible to at-
tacks of this borer. The borers usually begin work on the south
or southwest side of the trunk and most of the damage is found
in this area.
The adult beetle is bright copper colored and may be found
in pecan orchards from spring to late fall. The eggs are laid
on the sun-exposed side of the tree in cracks in the bark or in-
jured places on the tree. The larvae or borers are creamy white
and are easily recognized by the greatly enlarged and flattened
head. When full grown, the borer is about 1 inch long. There
is only 1 generation of this beetle a year.
Control.-Remove borers from their burrows with a knife,
taking care to injure the healthy bark as little as possible. Paint
exposed woody parts with a prepared pruning compound or a
mixture of 1 part creosote and 3 parts coal tar.







Florida Agricultural Experiment Stations


Fig. 40.-Pupa and larval burrow of the flatheaded apple tree borer in
the trunk of a young pecan tree.







Insects and Diseases of the Pecan in Florida


Give newly transplanted trees the best possible care until
well established. Proper cultivation, fertilization and pruning
are important. Normally vigorous trees with low heads rarely
suffer severe injury from this insect.
Preventive measures include wrapping the trunks of young
trees with heavy pa-
per or burlap from
March to November
to prevent egg lay-
ing. Trap logs may
be used in heavily in-
fested orchards.
These are newly cut
logs of pecan, hick-
ory or oak placed at
intervals in the or-
chard to attract the
egg-laying beetles to 1
the dying wood,
which they prefer.
Place these logs in
the orchard in early
spring and destroy
them the following tf
winter. Never leave
logs or prunings ly-
ing about in the or-
chard from one sea-
son to another.

RED-SHOULDERED
SHOT-HOLE BORER
This insect, Xylo- i
biops basilaris (Say), L ,
attacks only trees or Fig. 41.-Exit holes of adult beetles of the red-
shouldered shot-hole borer.
parts of trees that
that have been injured or are dying. It makes small round holes
in the bark of the pecan and other trees (Fig. 41). There are
several other similar species of shot-hole borers that also attack
devitalized trees.
Control.-Keep trees in a healthy, growing condition, as these
insects do not often attack healthy wood. Remove all dead limbs






44 Florida Agricultural Experiment Stations

and dying pecan trees and reduce as far as possible all sources of
infestation near the orchard.

TERMITES
Termites, Reticulitermes flavipes (Kollar), and occasionally
other species more commonly known as wood lice or white ants,
usually live in dead wood and many growers never think of them
as an insect pest of the pecan. However, pecan nursery stock
and small trees are sometimes killed by termites feeding in the
roots. Trees planted on recently cleared land containing stumps
and dead roots are most likely to be injured. The termites at-
tack the trees under ground and affected trees may show no
signs of injury until they are seriously damaged or die. The
tree may have the taproot or its branches tunnelled until only
a shell or the bark remains.
Control.-Recently cleared land should not be used for a pe-
can nursery or orchard until all dead wood and stumps are re-
moved. Only termite-resistant stakes as iron, heart pine or
wood treated with creosote should be used near newly planted
trees, as the stakes might become infested and the termites
spread to the trees.

DISEASES OF THE PECAN.
Three classes of diseases and 1 of injuries now seriously af-
fecting pecans in Florida are: (1) fungous, (2) bacterial, (3)
,nutritional and (4) injuries due to environment. The first 2 are
caused by specific organisms, the third is caused by a deficiency
of 1 or more mineral elements, and the fourth is composed of
injuries due to climatic conditions.

DISEASES DUE TO SPECIFIC ORGANISMS
SCAB
Pecan scab, Fusicladium effusum Wint., is 1 of the most im-
portant limiting factors in nut production, especially in the
Southeastern States, and its control is of vital importance. The
following varieties may be severely infected with scab in cer-
tain orchards in some parts of Florida: Schley, Success, Mahan,
Frotscher, Randall, Kennedy, Moneymaker, Moore, Nelson, Teche,
Curtis, Stuart and Elliot. Apparently all varieties of pecans
will eventually be susceptible to scab when proper strains of the
fungus become established in an orchard. Moneymaker, Teche,






44 Florida Agricultural Experiment Stations

and dying pecan trees and reduce as far as possible all sources of
infestation near the orchard.

TERMITES
Termites, Reticulitermes flavipes (Kollar), and occasionally
other species more commonly known as wood lice or white ants,
usually live in dead wood and many growers never think of them
as an insect pest of the pecan. However, pecan nursery stock
and small trees are sometimes killed by termites feeding in the
roots. Trees planted on recently cleared land containing stumps
and dead roots are most likely to be injured. The termites at-
tack the trees under ground and affected trees may show no
signs of injury until they are seriously damaged or die. The
tree may have the taproot or its branches tunnelled until only
a shell or the bark remains.
Control.-Recently cleared land should not be used for a pe-
can nursery or orchard until all dead wood and stumps are re-
moved. Only termite-resistant stakes as iron, heart pine or
wood treated with creosote should be used near newly planted
trees, as the stakes might become infested and the termites
spread to the trees.

DISEASES OF THE PECAN.
Three classes of diseases and 1 of injuries now seriously af-
fecting pecans in Florida are: (1) fungous, (2) bacterial, (3)
,nutritional and (4) injuries due to environment. The first 2 are
caused by specific organisms, the third is caused by a deficiency
of 1 or more mineral elements, and the fourth is composed of
injuries due to climatic conditions.

DISEASES DUE TO SPECIFIC ORGANISMS
SCAB
Pecan scab, Fusicladium effusum Wint., is 1 of the most im-
portant limiting factors in nut production, especially in the
Southeastern States, and its control is of vital importance. The
following varieties may be severely infected with scab in cer-
tain orchards in some parts of Florida: Schley, Success, Mahan,
Frotscher, Randall, Kennedy, Moneymaker, Moore, Nelson, Teche,
Curtis, Stuart and Elliot. Apparently all varieties of pecans
will eventually be susceptible to scab when proper strains of the
fungus become established in an orchard. Moneymaker, Teche,






44 Florida Agricultural Experiment Stations

and dying pecan trees and reduce as far as possible all sources of
infestation near the orchard.

TERMITES
Termites, Reticulitermes flavipes (Kollar), and occasionally
other species more commonly known as wood lice or white ants,
usually live in dead wood and many growers never think of them
as an insect pest of the pecan. However, pecan nursery stock
and small trees are sometimes killed by termites feeding in the
roots. Trees planted on recently cleared land containing stumps
and dead roots are most likely to be injured. The termites at-
tack the trees under ground and affected trees may show no
signs of injury until they are seriously damaged or die. The
tree may have the taproot or its branches tunnelled until only
a shell or the bark remains.
Control.-Recently cleared land should not be used for a pe-
can nursery or orchard until all dead wood and stumps are re-
moved. Only termite-resistant stakes as iron, heart pine or
wood treated with creosote should be used near newly planted
trees, as the stakes might become infested and the termites
spread to the trees.

DISEASES OF THE PECAN.
Three classes of diseases and 1 of injuries now seriously af-
fecting pecans in Florida are: (1) fungous, (2) bacterial, (3)
,nutritional and (4) injuries due to environment. The first 2 are
caused by specific organisms, the third is caused by a deficiency
of 1 or more mineral elements, and the fourth is composed of
injuries due to climatic conditions.

DISEASES DUE TO SPECIFIC ORGANISMS
SCAB
Pecan scab, Fusicladium effusum Wint., is 1 of the most im-
portant limiting factors in nut production, especially in the
Southeastern States, and its control is of vital importance. The
following varieties may be severely infected with scab in cer-
tain orchards in some parts of Florida: Schley, Success, Mahan,
Frotscher, Randall, Kennedy, Moneymaker, Moore, Nelson, Teche,
Curtis, Stuart and Elliot. Apparently all varieties of pecans
will eventually be susceptible to scab when proper strains of the
fungus become established in an orchard. Moneymaker, Teche,






44 Florida Agricultural Experiment Stations

and dying pecan trees and reduce as far as possible all sources of
infestation near the orchard.

TERMITES
Termites, Reticulitermes flavipes (Kollar), and occasionally
other species more commonly known as wood lice or white ants,
usually live in dead wood and many growers never think of them
as an insect pest of the pecan. However, pecan nursery stock
and small trees are sometimes killed by termites feeding in the
roots. Trees planted on recently cleared land containing stumps
and dead roots are most likely to be injured. The termites at-
tack the trees under ground and affected trees may show no
signs of injury until they are seriously damaged or die. The
tree may have the taproot or its branches tunnelled until only
a shell or the bark remains.
Control.-Recently cleared land should not be used for a pe-
can nursery or orchard until all dead wood and stumps are re-
moved. Only termite-resistant stakes as iron, heart pine or
wood treated with creosote should be used near newly planted
trees, as the stakes might become infested and the termites
spread to the trees.

DISEASES OF THE PECAN.
Three classes of diseases and 1 of injuries now seriously af-
fecting pecans in Florida are: (1) fungous, (2) bacterial, (3)
,nutritional and (4) injuries due to environment. The first 2 are
caused by specific organisms, the third is caused by a deficiency
of 1 or more mineral elements, and the fourth is composed of
injuries due to climatic conditions.

DISEASES DUE TO SPECIFIC ORGANISMS
SCAB
Pecan scab, Fusicladium effusum Wint., is 1 of the most im-
portant limiting factors in nut production, especially in the
Southeastern States, and its control is of vital importance. The
following varieties may be severely infected with scab in cer-
tain orchards in some parts of Florida: Schley, Success, Mahan,
Frotscher, Randall, Kennedy, Moneymaker, Moore, Nelson, Teche,
Curtis, Stuart and Elliot. Apparently all varieties of pecans
will eventually be susceptible to scab when proper strains of the
fungus become established in an orchard. Moneymaker, Teche,







Insects and Diseases of the Pecan in Florida


Curtis and Stuart varieties formerly were considered immune
to scab, but they have been found to be susceptible in some locali-
ties. However, scab on Curtis is mostly confined to young trees
growing in nurseries.
The scab fungus attacks the rapidly growing tissues of the
leaves, shoots and nuts. When these tissues cease growing,
they become completely immune. On highly susceptible varie-
ties such as Schley, defoliation often results, especially when
frequent infections occur beginning in early spring; but most
damage is to the
nuts, where losses
frequently range %g'r.
from 75 to 95 per-
cent. ZAlow


The scab fungus
is carried over win-
ter in the infected
spots on old leaves
and shucks (Fig. 42)
and lesions on the
shoots of the trees.
In the spring when
weather conditions
become favorable,
the dormant fungus
becomes active and
produces spores
which are spread to
the new leaves,
shoots and nuts
where, under suitable
conditions, they may
cause infections
(Fig. 43).


Fig. 42.-Schley nuts that received no spray.
The shucks are severely infected with the fungus
causing scab disease and they are opening pre-
maturely.


On varieties very susceptible to scab, such as Schley, the
primary infections on the foliage (Fig. 44) are irregular in out-
line and may be followed by some secondary infections. On
other varieties such as Moore, the spots are usually regular in
outline and are surrounded by a distinct halo (Fig. 45).
Infection of leaves, shoots and nuts by the scab fungus is
correlated with rainfall during spring and early summer. Fre-







Florida Agricultural Experiment Stations


quent rains and cloudy weather which keep the leaves wet over
night or for 12 hours or more favor infection. Under such con-
ditions initial infections may occur prior to the middle of April,
and these develop rapidly. By the latter part of April or the
first week in May new crops of spores are produced which cause
secondary infections under favorable conditions if no spraying
has been done. Rains which keep the leaves and nuts wet for


Fig. 43.-Early spring infections on Schley variety resulting from scab
carried over on old shucks from the previous season. Some of the leaflets
are infected with the fungus causing scab.







Insects and Diseases of the Pecan in Florida


12 to 18 hours provide a condition very favorable for infection.
The spores require 6 to 8 hours to germinate and cause infec-
tion. With these humid conditions it requires 1 to 2 weeks from
the time of infection until the scab lesions may be observed on
the new tissue of either leaves or nuts.
To prevent infection or to control scab, old leaves and shucks
from which the spores may be spread should not remain exposed
in the orchard. Furthermore, during rainy periods in early
spring and summer the leaves, shoots and nuts should have a
coating of an effective fungicide.


Fig. 44.-Primary scab infections
on foliage of Schley, a variety
highly susceptible to scab in most
localities.


Fig. 45.-Primary scab infections
on foliage of Moore.







Florida Agricultural Experiment Stations


The primary infections are first observed as elongated, olive-
brown lesions usually occurring on the veins of the under sides
of the leaves of susceptible varieties. These spots first appear
as very small pin points but soon enlarge and, with the occur-
rence of secondary infections, may cause areas of the leaves to
appear almost black due to the coalescing of the spots. On the
nuts the spots of infection are small, black, circular and slightly
raised at first but later may become sunken. Nuts of highly sus-
ceptible v a r i e t i e s
may have many in-
fections on them un-
i til practically the
O whole surface ap-
pears black.
Scab injury on
SSchley nuts is illus-
trated in Fig. 47 in
photographs made on
August 1. Of the 5
classes of nuts only
1, class 5, is unmar-
ketable, but nuts in
classes 3 and 4 are
poor in quality.
Untreated, severe-
ly infected nuts may
drop prematurely or
they may almost en-
tirely s top growth
and remain attached
to the shoots indefi-
Fig. 46.-Schley nuts that received one pre-
pollination spray of 4-1-100 bordeaux mixture, nitely. On the other
followed by three applications of 6-2-100 bor-h a n d, commercial
deaux. Photographed latter part of November. control of pecan scab
control of pecan scab
can be obtained when the nuts are sprayed according to the
recommended control schedule (Fig. 46).

RECOMMENDATIONS FOR PECAN SCAB CONTROL
Knock off all old shucks and leaf stems before the trees be-
gin to leaf out in spring. A slight jarring of trees will cause
most old shucks and leaf stems to fall when they are wet after
a rain or on misty or foggy days. It is preferable to bury shucks













CLASS 1* -
Nuts Grade A








CLASS 2
Nuts Grade A








CLASS 3
Nuts Grade B







CLASS 4
Nuts Grade B







CLASS 5
Nuts dropped
prematurely




Fig. 47.-Practically full grown Schley nuts illustrating degrees of scab in-
fection by classes and their relation to nut grades. Photo made August 1st.


* Definition of each class
Class Amount of infection
1 No infection
2 1-3 initial infections


3 4 or more initial infections
4 Few secondary infections
5 Numerous secondary infections







Florida Agricultural Experiment Stations


and leaves with a turning plow deep enough that they will not
be turned up again by disk harrows or other means of cultiva-
tion. Since most successful orchardists plant winter cover crops
in their orchards, turning under shucks and leaves is not prac-
tical. However, scab spores are washed down by the rain;
therefore, getting shucks and leaves on the ground will assist
materially in preventing foliage infection.
Pruning off low limbs will aid in scab control by letting in
sunlight and assisting in better air circulation.
Spraying.-A large number of fungicides, including various
strengths of bor-
deaux mixture, in-
soluble copper com-
Spounds, wettable sul-
4 furs, organic fungi-
cides and mercury
derivatives have been
tested for control of
pecan scab. Of these
the most effective 3
methods of control
are: 1, the use of
home-made bordeaux
mixture; 2, a split
schedule of bordeaux
mixture in the 1st
and 2nd applications,
then 2 pounds of zi-
ram (76 percent) to
100 gallons plus 1/4
Fig. 48.-Schley nuts showing results of early
spring infection. Secondary infection was pre- percent summer oil
vented by three thorough applications of 6-2-100 emulsion in the 3rd
bordeaux, the last about July 15. Photographed to 5th or 6th; 3, bor-
October 1. t r ha r
deaux mixture alter-
nating with 2 pounds zineb (65 percent) to 100 gallons plus 1/4
percent summer oil emulsion. When these are applied accord-
ing to the schedule given, the disease can be controlled with
slight or no injury to the foliage.
In wet summers a minimum of 6 applications are needed
for scab control in north Florida. The spray applications should
be made at approximately 3-week intervals during the summer.
Spraying should start when the pecan leaflets are half grown,







Insects and Diseases of the Pecan in Florida


about the second or third week in April, and end about the mid-
dle or last of August. For the complete spray schedule see
page 84.
Both timing and thorough-
ness of the spray application
are very important. Sometimes
weather conditions make it im-
possible to spray at the proper
time to prevent early infection
on the young nuts. When this
does occur and the trees are
properly sprayed during the
later applications, secondary in-
fection can be prevented and
good quality nuts may be pro-
duced (Fig. 48).

DOWNY SPOT


Downy spot, Mycosphaerella
caryigena Demaree & Cole, is a
foliage disease of pecans that
was first observed in south Geor-
gia and north Florida in 1927.
In north Florida the disease may
be seen first during late spring
or early summer as downy or
frosty spots on the lower sides
of the leaves (Fig. 49). This
appearance is due to production
of spores by the fungus. Dew,
fog and rain help spread the
spores from 1 leaf to another.
Later, after these spores have
been washed away or have de-
teriorated, greenish-yellow spots
remain that are clearly visible
on both sides of the leaves. As
the season advances the diseased
areas die and some premature
defoliation may occur.
The downy spot organism


Fig. 49.-White or "frosty" spots
on the under side of a pecan leaf
showing characteristic markings of
downy spot disease in the early
stages soon after formation of
conidiophores and conidia.







Florida Agricultural Experiment Stations


lives over winter in the diseased leaves, completing its life cycle
in them, and spores from the perithecial or winter stage are
liberated in large quantities the following spring, thereby in-
fecting the new foliage.
While all varieties are at-
tacked to some extent by the
f u n g u s, Moneymaker and
Stuart are most susceptible.
Control. The winter
spores of the causal organ-
ism are liberated from the
fruiting bodies in the old
leaves during rainy periods

of most varieties begins.
Where winter cover crops are
turned under about the first
of April, the sanitation ef-
fects from burying diseased
leaves help to control downy
spot.
Where spraying is done
to control scab, the first 2
s c a b applications of bor-
bi deaux mixture or bordeaux-

downy spot also. Where it
is not necessary to spray for
scab control, the first two
applications in the scab
spray schedule (see page 84)
will control downy spot.

PECAN LEAF BLOTCH
Fig. 50.-Early stage of leaf blotch Pecan leaf blotch, Myco-
on the under side of a leaflet. At this sphaerella dendroides (Cke.)
stage the conidiophores and conidia are
in clusters and the pimple-like peri- Demaree & Cole, is a foliage
thecia are just appearing to form the disease of nursery and or-
blotches, chard trees and is especially

prevalent in the vicinity of Monticello, Florida. The fruiting
bodies first appear on mature leaves in June or July as olive green
velvety tufts of conidiophores and spores on the undersurface.






Insects and Diseases of the Pecan in Florida


while yellow spots appear later on the upper surface of the leaves
(Fig. 50). Fruiting bodies of the perfect stage, black pimple-
like structures, make their appearance among the conidiophores
about midsummer; and after the spores have been washed away
by rain, or have otherwise deteriorated, groups of these pimple-
like structures unite, giving the leaves a black, shiny, blotched
appearance. Occasionally an entire leaflet is enveloped by co-
alescence of these blotches and premature defoliation results.
In contrast to the downy spot organism, the leaf blotch path-
ogen is only a weak parasite and does not attack orchard trees
unless they have been lowered in vigor by overcrowding, rosette
or attacks from borers, or have suffered from general neglect.
Nursery trees are more susceptible to attack than old trees and
the disease is especially prevalent where the nursery blight
disease is present. Under such conditions defoliation begins
with the basal leaves and the disease gradually progresses up-
ward until defoliation is complete with the exception of a few
leaves in the tops of the trees.
Control.-Leaf blotch and downy spot are similar in that
both causal organisms overwinter on fallen, decaying leaves.
The same sanitation measures-plowing under old leaves in early
spring-will materially reduce the development of leaf blotch.
Fungicides used for the control of scab and downy spot will
control the blotch disease. In orchards where only leaf blotch
is present, 1 application in June of low-lime bordeaux mixture
of the 6-2-100 formula, 6 pounds of copper sulfate plus 2 pounds
of hydrated lime to 100 gallons, will prevent the disease.

BROWN LEAF SPOT
Brown leaf spot, Cercospora fusca Rand, is a disease of minor
importance, especially on healthy, vigorous trees. It is preva-
lent throughout the entire pecan belt, but causes serious prema-
ture defoliation only in localities having a high rainfall and in
orchards where the trees lack vigor as a result of neglect. A
typical diseased leaflet is shown in Figure 51. Diseased spots
from primary infections are circular, reddish brown and often
develop grayish concentric zones. Later these spots are very
irregular in outline. Like pecan scab, brown leaf spot inoculum
is carried over winter in infected spots on old leaves. In Florida
the disease first appears in June or July, attacks only mature
leaves and, if not controlled, causes premature defoliation early
in October. Stuart is very susceptible, while all other are more







Florida Agricultural Experiment Stations


or less resistant, especially if a good cultural program is followed.
Control.-One application of 6-2-100 bordeaux mixture made
at any time between May 15 and June 15 is usually sufficient.

GNOMONIA LEAF SPOT
The gnomonia leaf spot,
Gnomonia dispora Demaree
& Cole, is another pecan dis-
ease of minor importance oc-
casionally observed in Flor-
ida and southern Georgia. It
first appears in June as a
small, inconspicuous brown
spot with no definite diagnos-
tic features. The spots may
enlarge to 1/9 inch or more in
diameter and become almost
black. The shape of the
spots varies from circular to
much elongated. The most
distinguishing characteristic
of the gnomonia leaf spot is
that the affected portion fre-
quently is confined to a nar-
row space between the lat-
eral veinlets, thus forming a
long, narrow, dead area
(Fig. 52).
The disease has not be-
come serious enough to justi-
fy control measures. So far
it has been found only on
rosetted trees, which sug-
gests that the fungus caus-
ing the spots is a weak par-
asite.

Fig. 51.-Pecan brown leaf spot on NURSERY BLIGHT
under side of leaf. The diseased spots
are characterized by concentric mark-
ings. In seasons of excessive
rainfall pecan nursery blight,
Elsinoe randii Jenkins & Bitancourt, becomes one of the most
important limiting factors in the production of budded pecan







Florida Agricultural Experiment Stations


or less resistant, especially if a good cultural program is followed.
Control.-One application of 6-2-100 bordeaux mixture made
at any time between May 15 and June 15 is usually sufficient.

GNOMONIA LEAF SPOT
The gnomonia leaf spot,
Gnomonia dispora Demaree
& Cole, is another pecan dis-
ease of minor importance oc-
casionally observed in Flor-
ida and southern Georgia. It
first appears in June as a
small, inconspicuous brown
spot with no definite diagnos-
tic features. The spots may
enlarge to 1/9 inch or more in
diameter and become almost
black. The shape of the
spots varies from circular to
much elongated. The most
distinguishing characteristic
of the gnomonia leaf spot is
that the affected portion fre-
quently is confined to a nar-
row space between the lat-
eral veinlets, thus forming a
long, narrow, dead area
(Fig. 52).
The disease has not be-
come serious enough to justi-
fy control measures. So far
it has been found only on
rosetted trees, which sug-
gests that the fungus caus-
ing the spots is a weak par-
asite.

Fig. 51.-Pecan brown leaf spot on NURSERY BLIGHT
under side of leaf. The diseased spots
are characterized by concentric mark-
ings. In seasons of excessive
rainfall pecan nursery blight,
Elsinoe randii Jenkins & Bitancourt, becomes one of the most
important limiting factors in the production of budded pecan







Insects and Diseases of the Pecan in Florida 55

trees, especially in north Florida. As its name implies, this dis-
ease is confined almost entirely to nursery trees.














































Fig. 52.-Gnomonia leaflet spot on pecan. Delimitation of the spots by the
leaflet veins is characteristic of the disease.







Florida Agricultural Experiment Stations


The fungus causing it invades both young and old leaflets,
and infections that are first observed in April result in small red-
dish lesions that develop on
r both surfaces of the leaves
*** (Fig. 53). Later the spots
on the upper surface of the
leaves turn ash-gray. Single
lesions usually are about 1/8
Sinch in diameter. These
spots, however, may unite by
secondary infections and
form a continuous 1 e s i o n
along each side of a vein.
Late season infections are
most numerous along the
midrib and larger veins. The
diseased areas are soon killed
by the invading fungus, the
tissues becoming brittle and
breaking out, resulting in
ragged margins and perfora-
tions.
Control.-Nursery blight
in Florida can be controlled
by applying 4-1-100 bor-
deaux mixture about April 5
to 15, and following this
with 3 applications of 6-2-
100 bordeaux mixture.
Th es e later applications
should be made at monthly
intervals, with the last 1 on
or about July 10 (Fig. 54).
Since the disease is car-
ried over winter on fallen
Fig. 53.--Early stages of nursery leaves in the nursery, de-
blight on pecan leaflet. leaves in the nursery, de-
stroying these old leaves by
plowing them under will aid materially in effecting control.

THREAD BLIGHT
Thread blight, Pellicularia koleroga Cke., attacks pecans and
numerous other woody plants throughout Florida. The fungus







Insects and Diseases of the Pecan in Florida


overwinters in compact masses of fungous tissues known as
sclerotia, which adhere to the bark of twigs and leaf petioles
(Fig. 55). The fungus threads or mycelium grow rapidly in May
and June from the sclerotia on the twigs onto the new petioles
and leaflets. In this manner the thread-like mycelium spreads
over the lower surface of the leaves, completely parasitizing and
killing them (Fig. 56), causing premature defoliation of the
affected trees. Under particularly favorable conditions the fun-
gus growing on the leaves produces tiny spores basidiosporess)
which are disseminated by wind, rain and dews. These spores
probably cause infection and explain the wide spreading of the
disease which is sometimes observed, although little is known
about them.
Most common symptom of thread blight during summer is
the matting together of dead leaves. These mats of dead leaves
hang from the shoots by the spider-web-like threads until frost
kills the fungus, allowing the leaves to fall to the ground.
Control.-The thread blight fungus usually attacks pecan
trees near forests or wood lots in which the fungus is present,
and spreads rapidly in damp localities or especially where the
pecan trees are crowded or neglected. Pruning away the lower
limbs and removing trees where they are crowded will assist in
controlling the disease. Where the infection is severe, 2 appli-

Fig. 54.-Spraying nursery trees with 6-2-100 bordeaux mixture, Monti-
cello, Florida. Approximately 100 gallons of spray material per acre re-
quired for this type of spraying.





Florida Agricultural Experiment Stations


cations of 6-2-100 bordeaux, second and third in the scab sched-
ule, will prevent or control the disease.
POWDERY MILDEW
Powdery mildew, Microsphaera alni Wint., is of minor im-
portance on pecans in Florida. This disease, like scab, affects


r


Fig. 55.-Left, compact masses (sclerotia) of the thread blight
fungus on a leaf petiole. Right, similar masses on a twig.
both foliage and nuts, forming a white superficial fungous
growth early in the growing season (Fi 57), generally in
July, while later the perithecial or winter stage develops on
the diseased spots. Occasionally premature defoliation occurs
under conditions very favorable for the spread and development







Insects and Diseases of the Pecan in Florida


of the fungus. When the nuts are infected early in the season,
the shucks split prematurely, causing shriveled kernels.
Control.-Most varieties of pecans grown commercially in
Florida are resistant to mildew, and where this disease is present
it is easily controlled by making 2 applications of 6-2-100 bor-
deaux mixture in June and July (see spray schedule, p. 84).
The same sanitary measures as those recommended for scab,






































Fig. 56.-The thread blight disease on pecan foliage. The leaflets are
withered and discolored.







Florida Agricultural Experiment Stations


downy spot, leaf blotch and nursery blight also will assist in
controlling powdery mildew.

PINK MOLD
Pink mold, Cephalothecium roseum Corda, is frequently ob-
served during late summer and early fall as a pinkish fungus
growth on the shucks of nuts that have been attacked by the
scab disease or where the shuck has been injured by mechanical
means, especially in-
sect punctures (Fig.
58). This pink mold
is caused by a sapro-
phytic fungus that
gains entrance into
the shuck and nuts
through scab spots
Sor other injury and
continues to develop
after the nuts have
matured. It will pen-
etrate the shell and
enter the kernel of
thin shell varieties,
causing a decay that
is known as "pink
rot." Affected nuts
leak oil and their
shells have an oiled
appearance and often
Fig. 57.-Powdery mildew in its early stages a strong rancid odor.
on Farley nuts. The white mycelium has mostly Control. Since
covered the surface of the nuts.
the pink mold fungus
is usually found on scabby nuts, it is most conspicuous on sus-
ceptible varieties, such as Schley, growing in yards where no
fungicide was used. A spray program that controls scab will
usually control pink rot. Some nuts become infected on the tree
prior to harvest; after harvest the mold does not spread from
infected to sound nuts.
WOOD ROT

All wounds on pecan trees provide a point of entrance for
wood-rotting fungi unless the injured surfaces are properly







Florida Agricultural Experiment Stations


downy spot, leaf blotch and nursery blight also will assist in
controlling powdery mildew.

PINK MOLD
Pink mold, Cephalothecium roseum Corda, is frequently ob-
served during late summer and early fall as a pinkish fungus
growth on the shucks of nuts that have been attacked by the
scab disease or where the shuck has been injured by mechanical
means, especially in-
sect punctures (Fig.
58). This pink mold
is caused by a sapro-
phytic fungus that
gains entrance into
the shuck and nuts
through scab spots
Sor other injury and
continues to develop
after the nuts have
matured. It will pen-
etrate the shell and
enter the kernel of
thin shell varieties,
causing a decay that
is known as "pink
rot." Affected nuts
leak oil and their
shells have an oiled
appearance and often
Fig. 57.-Powdery mildew in its early stages a strong rancid odor.
on Farley nuts. The white mycelium has mostly Control. Since
covered the surface of the nuts.
the pink mold fungus
is usually found on scabby nuts, it is most conspicuous on sus-
ceptible varieties, such as Schley, growing in yards where no
fungicide was used. A spray program that controls scab will
usually control pink rot. Some nuts become infected on the tree
prior to harvest; after harvest the mold does not spread from
infected to sound nuts.
WOOD ROT

All wounds on pecan trees provide a point of entrance for
wood-rotting fungi unless the injured surfaces are properly







Insects and Diseases of the Pecan in Florida


treated. Once these fungi gain entrance they spread quite rap-
idly through the wood and may endanger the entire tree. Some
wounds heal much more quickly than others. Wounds made
flush with the trunk or main branches heal more quickly than
those even of smaller size that are not flush (Fig. 59). Smooth,
carefully made wounds heal more quickly than those having
rough, jagged or irregular surface (Fig. 60).


Fig. 58.-Early and late development of the pink mold fungus
on Schley pecans.

Wood-rotting fungi usually can be prevented from entering
by painting the wounds once annually with a commercial tree
wound paint. A home-made treatment can be prepared by add-
ing 1 part of commercial creosote to 3 parts of coal tar. This
mixture is caustic and will slightly injure the cambium but the
wound will generally remain free of wood-rotting fungi and
eventually will heal.
CROWN GALL
Crown gall, Agrobacterium tumefaciens (E. F. Sm. & Town)
Conn, is a bacterial disease of pecan which does extensive dam-







62 Florida Agricultural Experiment Stations

age under certain conditions. Formerly it was considered a dis-
ease of nursery trees only (Fig. 61), but in more recent years
it has been found well established in orchards, especially on old
trees, where it may become severe enough to kill them (Fig. 62).
On trees of bearing age the disease is confined mostly to the
roots and base of the tree trunk, but occasionally lateral roots
also are affected. Wart-like, somewhat fragile growths, often
extending several inches above the surface soil and from a few
inches to a foot or more in diameter, are the orchard-tree char-
acteristics of the crown gall disease. Because of their fragility,
these galls are often broken off the roots and become scat-
tered on top of the soil when the orchard is being cultivated.


-<.,


Fig. 59.-Wrong way to prune trees. Wounds of this type will be slow
in healing and thus will usually allow the entrance of wood-rotting fungi.
See Fig. 60.







Insects and Diseases of the Pecan in Florida


Control.-It is important that all infected nursery stock be
destroyed, preferably by burning at time of digging. Recent
experiments indicate that soaking nursery trees 1 hour in 400
ppm terramycin will inhibit the disease. A person who plans to
plant a pecan orchard should carefully select disease-free trees,
or purchase inspected stock. This will prevent the spread of
crown gall into the new orchard.























-^ r
Fig. 60.-In pruning make the cuts flush with the tree trunk to hasten
healing of the wound. These cuts were painted with the recommended coal
tar-creosote paint mixture. Photographed two years after cuts were made.

Where young orchard trees are infected, the galls should be
removed and burned and the wounds painted with a mixture of
1 part creosote to 3 parts coal tar. This will help prevent the
spread of the disease to healthy parts of the tree. To prevent
the spread to healthy trees, infected trees should not be culti-
vated or harrowed.







Florida Agricultural Experiment Stations


DISEASES DUE TO NUTRITIONAL OR
ENVIRONMENTAL FACTORS
ROSETTE
Rosette is a nutritional disease caused by an indaquate
amount of available zinc in the soil.


Fig. 61.-Crown gall disease on nursery stock. Trees so infected should
be burned to prevent further spread of the disease.

Prior to discovery in 1931 of the cause and control of rosette,
most bearing pecan trees in the Southeast were affected. Since
then most growers have treated the soil with zinc sulfate, and







Florida Agricultural Experiment Stations


DISEASES DUE TO NUTRITIONAL OR
ENVIRONMENTAL FACTORS
ROSETTE
Rosette is a nutritional disease caused by an indaquate
amount of available zinc in the soil.


Fig. 61.-Crown gall disease on nursery stock. Trees so infected should
be burned to prevent further spread of the disease.

Prior to discovery in 1931 of the cause and control of rosette,
most bearing pecan trees in the Southeast were affected. Since
then most growers have treated the soil with zinc sulfate, and







Insects and Diseases of the Pecan in Florida


when once corrected in this way, rosette can be classed as a
minor problem, since repeated applications usually are not needed.


-. .



Fig. 62.-This 25-year-old tree that was probably infected with crown
gall when transplanted, had its roots destroyed by the disease and was
killed, the tree blowing down soon after its death.

Yellow mottling, or chlorosis, and crinkling of the leaves in
the tops of trees are characteristic of rosette in the early stage
of its development. As the disease progresses, the symptoms
appear on the leaves on the lower branches. In advanced stages
the leaves become dwarfed, the internodes are shortened and
gradually the twigs and branches in the tops of the trees die
(Fig. 63).
Often it is difficult to detect rosette because the first symp-
toms usually are in the tops of the trees and the trees may be
damaged severely before its presence is noticed. Any abnormal
color of the foliage in the top of a tree suggests the possibility







Florida Agricultural Experiment Stations


of rosette. If the leaflets of the terminal shoots near the ground
are examined carefully, they frequently show yellowing between
the veins which is characteristic of the disease. Severely ro-
setted trees usually are non-productive and may become so
weakened that they die from attacks of borers or from other
causes. However, rosette alone has never been known to kill
pecan trees.


Fig. 63.-A tree seriously affected with the rosette disease. See Fig. 64.

Rosette occurs under variable conditions in Florida. Eroded
or light sandy soils or those deficient in organic matter seem to
favor its development. Trees on well-drained, medium to heavy
soil types are mostly free from rosette except under unusual con-
ditions, such as the addition of heavy applications of lime to the
soil to facilitate the growth of winter cover crops.







Insects and Diseases of the Pecan in Florida


A varietal resistance or susceptibility to rosette seems to
exist. Stuart is most susceptible, while Moneymaker in most
localities usually is quite resistant.


Fig. 64.-The same tree shown in Fig. 63 two years later, aiter two
annual applications of 10 pounds of zinc sulfate to the soil.

Control.-Rosette may be corrected by applying zinc sulfate
in solution as a spray to the trees or appying the dry salt to the
soil; the method of application is determined largely by local
conditions. Soil applications are not practical in orchards grow-
ing on neutral or alkaline soils. Where growers are prepared
to spray, this method is satisfactory regardless of the soil con-
dition. Three applications of spray solution consisting of 2







Florida Agricultural Experiment Stations


pounds of 36 percent zinc sulfate in 100 gallons of water will
correct rosette where the disease is present only in the mild
form. The first application should be made as soon after pollina-
tion as possible, and this should be followed by additional appli-
cations at intervals of 3 to 4 weeks. This schedule should be
followed annually until all signs of the disease have been elim-
inated; then watch regularly for the first signs of its recurrence,
since it is likely to reappear at any time.
Growers can combine zinc sulfate with bordeaux mixture
(see combination insect and disease spray schedule). Use 4
pounds of zinc sulfate to 100 gallons of bordeaux mixture, since
the lime in the bordeaux mixture somewhat reduces the effec-
tiveness of the zinc. Since zinc sulfate is very corrosive, it is
essential that the spray tank and pump be rinsed thoroughly
with water at the conclusion of each day's spraying.
Soil Applications.-Since most Florida soils where pecans are
commercially grown are acid, zinc sulfate applied to the soil will
produce more satisfactory results than spray applications be-
cause of its lasting effect. The zinc sulfate should be evenly
broadcast from near the trunk to beyond the limb spread. The
rate of application is determined largely by severity of the dis-
ease, nature of the soil and size of the trees.
On bearing trees not severely affected by rosette the symp-
toms usually disappear after 1 application of 5 pounds of zinc
sulfate per tree. Trees severely affected may require up to 10
pounds annually, over a period of 2 or more years, to overcome
the disease (Figs. 63 and 64).
February and March are the best months to apply zinc sul-
fate for rosette control. It may be applied later, but the time
of recovery will be delayed. If not applied until the deficiency
symptoms are present on the leaves, little or no correction of
the disorder will be evident until the following year.
Cultivating the zinc sulfate into the soil is desirable where
practicable, as this brings about quicker results and prevents
heavy rains from washing it away from the trees. However,
where winter cover crops are grown it is not practical to culti-
vate immediately if the zinc sulfate is applied in February or
March as recommended. The chemical may cause slight burning
of the winter cover crop, especially if it is not evenly distributed,
but the plants usually show no permanent damage under good
growing conditions.







Insects and Diseases of the Pecan in Florida


Fig. 65.-Mouse ear disease of pecan caused by a deficiency of Manganese.
Normal sized leaflet at the bottom of the photograph.







Florida Agricultural Experiment Stations


MOUSE EAR (LITTLE LEAF)
In the more pronounced cases of mouse ear (little leaf) the
leaflets fail to develop to normal size; the length and width are
reduced to about 1/3 or 1/2 inch. The leaf itself is often reduced
to a length of only 1 to 2 inches, exclusive of the petiole or leaf
stem. A slightly affected leaflet may be normal in size, the only
visible symptom of the disease being the blunt point (Fig. 65).
Some trees have been so severely affected that all their leaves
were composed of leaflets of the extremely rounded and dwarfed
type. On some trees the disease may be found only on certain
branches, whereas other limbs produce normal leaves and shoots.
Badly affected trees do not bear nuts and their growth is greatly
retarded. Considerable evidence indicates that some trees re-
cover after 1 or more years, whereas it is definitely known that
the trouble has persisted in others for a number of years.
Gammon and Sharpe 5 found that the mouse ear condition is
caused by a deficiency of manganese. Spraying the trees with
1 or 2 percent manganese sulfate or applying 2 to 4 pounds of
manganese sulfate to the soil of mature pecan trees caused about
a 50 percent recovery in 2 years.
This disease is of minor importance; as it seldom occurs under
orchard conditions. When found, diseased trees are usually
growing in city gardens and lawns in soil with high pH, 6.8 to
7.4. It may occur near houses where lime has been dumped
on the ground under the tree. It has been seen in a number
of states bordering the Atlantic and Gulf coasts from North
Carolina to Mississippi.

SPANISH MOSS
The common gray or Spanish moss, Tillandsia usneoides L.,
occasionally becomes noxious to pecan trees, particularly in
neglected orchards, in poorly drained locations, and especially
when the trees are growing in proximity to live oak trees.
The moss will grow not only on trees but also on many inani-
mate objects. Abundant accumulations of Spanish moss have
a retarding effect upon the vigor and growth of the tree as a
result of the shading effects produced by the masses of moss
(Fig. 66).

SGammon, N., Jr., and R. H. Sharpe. Mouse Ear a Managanese Defi-
ciency of Pecans. Amer. Soc. Hort. Sci. 68: 195-200. 1956.







Florida Agricultural Experiment Stations


MOUSE EAR (LITTLE LEAF)
In the more pronounced cases of mouse ear (little leaf) the
leaflets fail to develop to normal size; the length and width are
reduced to about 1/3 or 1/2 inch. The leaf itself is often reduced
to a length of only 1 to 2 inches, exclusive of the petiole or leaf
stem. A slightly affected leaflet may be normal in size, the only
visible symptom of the disease being the blunt point (Fig. 65).
Some trees have been so severely affected that all their leaves
were composed of leaflets of the extremely rounded and dwarfed
type. On some trees the disease may be found only on certain
branches, whereas other limbs produce normal leaves and shoots.
Badly affected trees do not bear nuts and their growth is greatly
retarded. Considerable evidence indicates that some trees re-
cover after 1 or more years, whereas it is definitely known that
the trouble has persisted in others for a number of years.
Gammon and Sharpe 5 found that the mouse ear condition is
caused by a deficiency of manganese. Spraying the trees with
1 or 2 percent manganese sulfate or applying 2 to 4 pounds of
manganese sulfate to the soil of mature pecan trees caused about
a 50 percent recovery in 2 years.
This disease is of minor importance; as it seldom occurs under
orchard conditions. When found, diseased trees are usually
growing in city gardens and lawns in soil with high pH, 6.8 to
7.4. It may occur near houses where lime has been dumped
on the ground under the tree. It has been seen in a number
of states bordering the Atlantic and Gulf coasts from North
Carolina to Mississippi.

SPANISH MOSS
The common gray or Spanish moss, Tillandsia usneoides L.,
occasionally becomes noxious to pecan trees, particularly in
neglected orchards, in poorly drained locations, and especially
when the trees are growing in proximity to live oak trees.
The moss will grow not only on trees but also on many inani-
mate objects. Abundant accumulations of Spanish moss have
a retarding effect upon the vigor and growth of the tree as a
result of the shading effects produced by the masses of moss
(Fig. 66).

SGammon, N., Jr., and R. H. Sharpe. Mouse Ear a Managanese Defi-
ciency of Pecans. Amer. Soc. Hort. Sci. 68: 195-200. 1956.







Insects and Diseases of the Pecan in Florida


Fig. 66.-Thirty-five-year-old tree almost covered with Spanish moss.

The importance of good orchard management is indicated by
the photographs of 2 adjacent orchards, one neglected and the
other receiving a complete cultural program including fertili-
zation, cultivation and spraying (Figs. 67 and 68).
Control.-This moss needs sunlight for best growth, and by
inaugurating an improved cultural and fertility program the
trees are usually invigorated so that they soon keep the moss
in check. Although no spray program has been developed spe-
cifically to control it, the moss is rarely observed growing on
trees that have been sprayed with bordeaux mixture, ziram or
zineb.






Florida Agricultural Experiment Stations


Sharpe and Gammon 6 reported that spraying with the 6-2-
100 bordeaux mixture during the growing season for controlling
pecan diseases has killed Spanish moss. They also reported that
arsenate of lead used at the rate of 2 pounds per 100 gallons of
water proved to be a satisfactory killing agent for Spanish moss,
and as good as the low-lime bordeaux mixture. Moss has been
killed also during the dormant period by thoroughly wetting it
with 10-2-100 bordeaux. It is necessary to apply all materials
to pecan trees with a sprayer of sufficient power and volume to
effect a satisfactory coverage. The dead moss will hang in the
trees for some time but eventually will be blown out. If the moss
is hanging in heavy, thick masses, it may require a second ap-
plication to kill all of it. An improved cultural and fertility
program will usually invigorate trees enough to keep the moss
in check.
LICHENS
Lichens frequently occur on the trunks and branches of the
pecan tree. They are considered harmless, but occasionally may
cause some injury to pecan trees mechanically by shading, es-
pecially in the more humid climate in the vicinity of the Gulf
Coast. Likewise, they give the tree an unsightly and unkept
appearance.

Sharpe, R. H., and Nathan Gammon, Jr. Pecan Growing in Florida.
Fla. Agr. Exp. Stat. Bul. 601: 37. 1958.


Fig. 67.-An unsprayed and neglected orchard.







Insects and Diseases of the Pecan in Florida


Lichens are low forms of plant life that grow in humid locali-
ties. They are not single plants but composite organisms made
up of algae which are contained in an enveloping mesh of fungus
filaments and, like mosses, obtain their food chiefly from the
air. Also like mosses, they thrive on inanimate objects such
as fence posts and rocks, as well as trunks and branches and
occasionally the foliage of some trees.
A common form is the grayish-green-paper-like growth that
occurs on the bark of pecan trees (Fig. 69). This growth may
Cover areas an inch or more in diameter, or it may make an ir-
regular patch several inches in area. The edges are usually free,
lobed and curl upward.
Control.-Since lichens are not considered to be injurious to
pecan trees, no spray program has been worked out for their
control. However, almost any standard fungicide, including
bordeaux mixture, lime-sulfur solutions or organic coppers, will
readily control lichens. They are never found growing on trees
that are properly sprayed with bordeaux mixture for the control
of scab and other pecan diseases.

Fig. 68.-This sprayed, fertilized and cultivated orchard, adjoins and is
separated by a fence line from the neglected one. (Fig. 67.)






Florida Agricultural Experiment Stations


INJURIES DUE TO CLIMATIC CONDITIONS
WINTER INJURY
Winter injury is a disorder usually found on young, vigorous,
late-growing pecan trees or those that were defoliated in sum-
mer and put out a new crop of leaves late in the season.
It is not always confined to young trees. Older trees, espe-
cially those that have received heavy applications of nitrogen
which tend to keep them in a vegetative condition late in the
season, may be injured severely by sudden freezes.
Winter injury is easily detected by the experienced pecan
grower. The indications are dead or dying trees in early sum-
mer, with vigorous sprouts
growing up from the roots
somewhat later. Close exam-
ination will show that the
trunks of the trees have been
damaged near the ground.
The affected tree usually foli-
ates and grows normally in
the spring but the leaves
i wither and the tree suddenly
dies as soon as hot weather
begins. Shothole borers and
other insects are sometimes
present but their damage is
of a secondary nature. By
cutting through the bark into
the cambium layer it is easy
to detect the "sour-sap" and
discolored wood.
Control.-Handle y o u n g
pecan orchards with extreme
care to prevent winter injury.
Fertilize young trees only in
early spring and do not culti-
vate later than midsummer,
Fig. 69.-Lichens on a pecan twig. except at time of planting
winter cover crops in the fall
when the trees are approaching dormancy. This method of
handling young trees will help prevent vegetative growth late
in the season and the trees will go into the winter with the wood
in a mature and hardy condition.






Florida Agricultural Experiment Stations


INJURIES DUE TO CLIMATIC CONDITIONS
WINTER INJURY
Winter injury is a disorder usually found on young, vigorous,
late-growing pecan trees or those that were defoliated in sum-
mer and put out a new crop of leaves late in the season.
It is not always confined to young trees. Older trees, espe-
cially those that have received heavy applications of nitrogen
which tend to keep them in a vegetative condition late in the
season, may be injured severely by sudden freezes.
Winter injury is easily detected by the experienced pecan
grower. The indications are dead or dying trees in early sum-
mer, with vigorous sprouts
growing up from the roots
somewhat later. Close exam-
ination will show that the
trunks of the trees have been
damaged near the ground.
The affected tree usually foli-
ates and grows normally in
the spring but the leaves
i wither and the tree suddenly
dies as soon as hot weather
begins. Shothole borers and
other insects are sometimes
present but their damage is
of a secondary nature. By
cutting through the bark into
the cambium layer it is easy
to detect the "sour-sap" and
discolored wood.
Control.-Handle y o u n g
pecan orchards with extreme
care to prevent winter injury.
Fertilize young trees only in
early spring and do not culti-
vate later than midsummer,
Fig. 69.-Lichens on a pecan twig. except at time of planting
winter cover crops in the fall
when the trees are approaching dormancy. This method of
handling young trees will help prevent vegetative growth late
in the season and the trees will go into the winter with the wood
in a mature and hardy condition.








Insects and Diseases of the Pecan in Florida


SUNSCALD

Injury resulting from sunscald is sometimes confused with
winter injury. The symptoms are dead or cankerous areas,
usually on the southwest side of the trees or on the tops of larger
branches. Like winter injury, sunscald occurs mostly on young
trees, but also on older ones that have been cut back for top-
working to some other variety. Bright sunshine on summer
days which raises the temperature of unshaded bark to a lethal
point or on winter days which raises the bark temperature dur-


r r
-AO

AttK


SIN.K


,- ,- -- .4 -


Fig. 70.-Tree struck by lightning in June, with bark split on trunk to
the ground. Some branches died about four week later, while the remain-
der of the tree recovered slightly. Photographed August 15.







Florida Agricultural Experiment Stations


ing the daytime only, followed by a sudden and relatively severe
drop in temperature at night, is the probable cause of sunscald.
The dead areas in the bark furnish ideal entrance places for
borers and other insects and for wood-rotting fungi.
Control.-One of the best methods of control is to head the
young trees as close to the ground as practicable. Do not prune
off lower limbs until the trees have advanced several growing
seasons, as the low lateral limbs increase the protective shading
of the trunk. Wrapping the trunks with gunny sacks or white-
washing them will aid in preventing sunscald.

LIGHTNING INJURY
Lightning frequently causes a type of injury to pecan trees
that is often mistaken for the effects of some parasitic disease.
Observations indicate that there are very few orchards where
the trees have reached bearing age without at least 1 tree having
been struck by lightning.
When a pecan tree is struck by lightninii. the principal vis-
ible injury may be confined either to the limbs and branches or
to the tree trunk (Fig. 70). The visible injury may consist of a
narrow split in the bark extending from a branch in the top
down the trunk to the ground, or the bark may be completely
peeled from the trunk, especially near the ground. If the bark
is only split the tree usually survives, but if it is peeled from
the trunk the tree dies within a few weeks. Following lightning
injury there is a yellowing of the leaves and they soon begin
to drop, resulting in partial to complete defoliation. Defoliation
usually occurs 30 to 60 days after the tree has been struck.
Observations indicate that definite signs of lightning injury
are confined to the trees that receive direct hits.
Control.-There is no practical control of lightning, but the
injuries should be treated. If the tree is killed outright, remove
it to prevent it becoming infested by borers that later may dam-
age other trees in the planting. The limbs which are killed
should be pruned out and the wounds painted with the coal tar-
creosote mixture as recommended under Wood Rot. The grower
should not act too hastily on removing injured trees, since a
large percentage eventually recover.







Insects and Diseases of the Pecan in Florida


INSECTICIDES AND FUNGICIDES

PREPARATION OF BORDEAUX MIXTURE
Home-made low-lime bordeaux mixture, even after more than
30 years' investigations, is still one of the best and most econom-
ical fungicides for the control of pecan scab and other parasitic
leaf diseases. Furthermore, there is no better or cheaper form
of bordeaux mixture known than that made at home with blue-
stone (copper sulfate), lime and water. Growers are advised
to use the finely powdered or "snow" form of bluestone and a
high-calcium hydrated lime for making the bordeaux mixture.
Powdered bluestone or copper sulfate is in particles about the
size of granulated sugar and dissolves rapidly in water. This
"snow" form of bluestone costs slightly more than the large
crystals but the added cost is offset by the savings of time and
labor in dissolving it.
Hydrated lime can be purchased in 50-pound sacks in most
towns. Although hydrated lime as ordinarily sold in the South-
east, especially that manufactured in Alabama and Tennessee, is
usually satisfactory for making bordeaux mixture, growers nev-
ertheless should demand that it contain at least 98 percent cal-
cium hydroxide. The use of hydrated lime has several advan-
tages over quick lime. It is properly slaked when purchased,
and if stored in the bags and in a dry place it deteriorates slowly.
It is relatively free from grit, and a "milk of lime" (a suspension
of 6 pounds of lime stirred into about 5 gallons of water) can be
prepared in less time than is required with quick lime.
A 6-2-100 bordeaux mixture for use in a 300-gallon spray tank
may be prepared in the following manner: Weigh out 18 ,po:,unds
of powdered (snow form) bluestone (copper sulfate) and 6
pounds of hydrated lime.7 Add about 5 gallons of water to the
lime in a separate container to make the milk of lime mixture.
The bluestone may be dissolved by placing it in the strainer of
the spray tank while the tank is being filled. When the tank
is about 3/4 full and all the bluestone is dissolved, the milk of
lime should be slowly added with the agitator running so as to
mix the lime thoroughly with the bluestone solution.

SIn preparing the 4-1-100 bordeaux mixture, weigh out 12 pounds of
copper sulfate and 3 pounds of hydrated lime for a 300-gallon spray tank.







Insects and Diseases of the Pecan in Florida


INSECTICIDES AND FUNGICIDES

PREPARATION OF BORDEAUX MIXTURE
Home-made low-lime bordeaux mixture, even after more than
30 years' investigations, is still one of the best and most econom-
ical fungicides for the control of pecan scab and other parasitic
leaf diseases. Furthermore, there is no better or cheaper form
of bordeaux mixture known than that made at home with blue-
stone (copper sulfate), lime and water. Growers are advised
to use the finely powdered or "snow" form of bluestone and a
high-calcium hydrated lime for making the bordeaux mixture.
Powdered bluestone or copper sulfate is in particles about the
size of granulated sugar and dissolves rapidly in water. This
"snow" form of bluestone costs slightly more than the large
crystals but the added cost is offset by the savings of time and
labor in dissolving it.
Hydrated lime can be purchased in 50-pound sacks in most
towns. Although hydrated lime as ordinarily sold in the South-
east, especially that manufactured in Alabama and Tennessee, is
usually satisfactory for making bordeaux mixture, growers nev-
ertheless should demand that it contain at least 98 percent cal-
cium hydroxide. The use of hydrated lime has several advan-
tages over quick lime. It is properly slaked when purchased,
and if stored in the bags and in a dry place it deteriorates slowly.
It is relatively free from grit, and a "milk of lime" (a suspension
of 6 pounds of lime stirred into about 5 gallons of water) can be
prepared in less time than is required with quick lime.
A 6-2-100 bordeaux mixture for use in a 300-gallon spray tank
may be prepared in the following manner: Weigh out 18 ,po:,unds
of powdered (snow form) bluestone (copper sulfate) and 6
pounds of hydrated lime.7 Add about 5 gallons of water to the
lime in a separate container to make the milk of lime mixture.
The bluestone may be dissolved by placing it in the strainer of
the spray tank while the tank is being filled. When the tank
is about 3/4 full and all the bluestone is dissolved, the milk of
lime should be slowly added with the agitator running so as to
mix the lime thoroughly with the bluestone solution.

SIn preparing the 4-1-100 bordeaux mixture, weigh out 12 pounds of
copper sulfate and 3 pounds of hydrated lime for a 300-gallon spray tank.







78 Florida Agricultural Experiment Stations

ZIRAM 8 AND ZINEB 9
These are new and effective fungicides containing zinc salts
of the organic carbamate compounds as the active agents. They
are, compatible with insecticides such as nicotine sulfate, DDT,
parathion and toxaphene that are used for the control of pecan
insects.
A 2/100 spray mixture for use in a 500-gallon sprayer tank
may be made by weighing 10 pounds of the material in a con-
tainer and adding sufficient water to make a paste. Then keep
adding water until it thins out. Pour the mixture into the
sprayer tank while it is being filled with water. It is preferable
to delay the addition of the slurry until the tank is nearly filled
with water to insure the most complete suspension possible of
the zinc salts in the water. These zinc salts are heavy and sep-
arate from the water quickly. Therefore, the mixture must be
thoroughly agitated while it is being applied. One quart of sum-
mer oil emulsion added to each 100 gallons of spray mixture is
an excellent sticker spreader.

DDT
DDT is 1 of the organic insecticides. It is available for use
as an insecticide as a wettable powder containing either 50 or 75
percent DDT and as an emulsifiable liquid containing 25 percent
DDT by weight. The wettable powders are generally preferred
for making spray mixtures for application to pecan trees.

PARATHION
Parathion is 1 of the organic phosphorus insecticides. It is
available for use as a wettable powder containing 15 or 25 per-
cent parathion.
SUMMER OIL EMULSIONS
The summer oil emulsions are chemically inert and are not
likely to injure the foliage or nuts, when used as a spreader-
sticker with bordeaux mixture or any of the new organic fungi-
cides and insecticides that are recommended for use on pecans
as wettable powders.

8 Contains zinc dimethyl-dithiocarbamate as the active agent. Trade
names for this material are Zerlate, Karbam White, Methasan, Zimate and
others.
I Contains zinc ethylene bis-dithiocarbamate as the active agent. Trade
names for this material are Dithane Z-78 and others.







78 Florida Agricultural Experiment Stations

ZIRAM 8 AND ZINEB 9
These are new and effective fungicides containing zinc salts
of the organic carbamate compounds as the active agents. They
are, compatible with insecticides such as nicotine sulfate, DDT,
parathion and toxaphene that are used for the control of pecan
insects.
A 2/100 spray mixture for use in a 500-gallon sprayer tank
may be made by weighing 10 pounds of the material in a con-
tainer and adding sufficient water to make a paste. Then keep
adding water until it thins out. Pour the mixture into the
sprayer tank while it is being filled with water. It is preferable
to delay the addition of the slurry until the tank is nearly filled
with water to insure the most complete suspension possible of
the zinc salts in the water. These zinc salts are heavy and sep-
arate from the water quickly. Therefore, the mixture must be
thoroughly agitated while it is being applied. One quart of sum-
mer oil emulsion added to each 100 gallons of spray mixture is
an excellent sticker spreader.

DDT
DDT is 1 of the organic insecticides. It is available for use
as an insecticide as a wettable powder containing either 50 or 75
percent DDT and as an emulsifiable liquid containing 25 percent
DDT by weight. The wettable powders are generally preferred
for making spray mixtures for application to pecan trees.

PARATHION
Parathion is 1 of the organic phosphorus insecticides. It is
available for use as a wettable powder containing 15 or 25 per-
cent parathion.
SUMMER OIL EMULSIONS
The summer oil emulsions are chemically inert and are not
likely to injure the foliage or nuts, when used as a spreader-
sticker with bordeaux mixture or any of the new organic fungi-
cides and insecticides that are recommended for use on pecans
as wettable powders.

8 Contains zinc dimethyl-dithiocarbamate as the active agent. Trade
names for this material are Zerlate, Karbam White, Methasan, Zimate and
others.
I Contains zinc ethylene bis-dithiocarbamate as the active agent. Trade
names for this material are Dithane Z-78 and others.







78 Florida Agricultural Experiment Stations

ZIRAM 8 AND ZINEB 9
These are new and effective fungicides containing zinc salts
of the organic carbamate compounds as the active agents. They
are, compatible with insecticides such as nicotine sulfate, DDT,
parathion and toxaphene that are used for the control of pecan
insects.
A 2/100 spray mixture for use in a 500-gallon sprayer tank
may be made by weighing 10 pounds of the material in a con-
tainer and adding sufficient water to make a paste. Then keep
adding water until it thins out. Pour the mixture into the
sprayer tank while it is being filled with water. It is preferable
to delay the addition of the slurry until the tank is nearly filled
with water to insure the most complete suspension possible of
the zinc salts in the water. These zinc salts are heavy and sep-
arate from the water quickly. Therefore, the mixture must be
thoroughly agitated while it is being applied. One quart of sum-
mer oil emulsion added to each 100 gallons of spray mixture is
an excellent sticker spreader.

DDT
DDT is 1 of the organic insecticides. It is available for use
as an insecticide as a wettable powder containing either 50 or 75
percent DDT and as an emulsifiable liquid containing 25 percent
DDT by weight. The wettable powders are generally preferred
for making spray mixtures for application to pecan trees.

PARATHION
Parathion is 1 of the organic phosphorus insecticides. It is
available for use as a wettable powder containing 15 or 25 per-
cent parathion.
SUMMER OIL EMULSIONS
The summer oil emulsions are chemically inert and are not
likely to injure the foliage or nuts, when used as a spreader-
sticker with bordeaux mixture or any of the new organic fungi-
cides and insecticides that are recommended for use on pecans
as wettable powders.

8 Contains zinc dimethyl-dithiocarbamate as the active agent. Trade
names for this material are Zerlate, Karbam White, Methasan, Zimate and
others.
I Contains zinc ethylene bis-dithiocarbamate as the active agent. Trade
names for this material are Dithane Z-78 and others.







Insects and Diseases of the Pecan in Florida


NICOTINE
Nicotine is an extract obtained from the stems and leaves
of tobacco, mostly from the waste products in cigar and cigaret
manufacture. It is usually sold as nicotine sulfate, containing
40 percent of actual nicotine. The nicotine sulfate is not rapidly
volatile and is employed chiefly in the preparation of orchard
sprays. Nicotine sulfate was formerly used extensively for aphid
control but in this bulletin it is recommended only in phylloxera
control.
MALATHION
Malathion is 1 of the new phosphate insecticides. However,
it is more toxic to insects than to mammals and therefore is safer
to use than most other phosphorus insecticides. It is available
as emulsifiable concentrate and as 25 percent wettable powder
for use as sprays and as 4 and 5 percent malathion dust.

EPN
EPN is an organic phosphorus insecticide. It is available
as an emulsifiable concentrate and 25 percent wettable powder
for use as sprays and as a 1, 2 and 3 percent dust.

GUTHION
Guthion is an organic phosphate insecticide. It is available
as emulsifiable concentrate and 25 percent wettable powder for
use as spray and also as a 21/2 percent dust and 21/2 percent
granular.
DEMETON
Demeton, a systemic insecticide, is a phosphatic material
used principally for the control of aphids, mites and related in-
sects. It is available as a concentrate formulation containing 26.2
percent by weight of actual material. It should be handled and
used as recommended by manufacturer.

LIME-SULFUR
The concentrated commercial liquid lime-sulfur usually tests
about 330 on the Baume hydrometer. This material should
always be diluted. Lime-sulfur should never be used with soap
or with soap-oil emulsions without stabilizers.







Insects and Diseases of the Pecan in Florida


NICOTINE
Nicotine is an extract obtained from the stems and leaves
of tobacco, mostly from the waste products in cigar and cigaret
manufacture. It is usually sold as nicotine sulfate, containing
40 percent of actual nicotine. The nicotine sulfate is not rapidly
volatile and is employed chiefly in the preparation of orchard
sprays. Nicotine sulfate was formerly used extensively for aphid
control but in this bulletin it is recommended only in phylloxera
control.
MALATHION
Malathion is 1 of the new phosphate insecticides. However,
it is more toxic to insects than to mammals and therefore is safer
to use than most other phosphorus insecticides. It is available
as emulsifiable concentrate and as 25 percent wettable powder
for use as sprays and as 4 and 5 percent malathion dust.

EPN
EPN is an organic phosphorus insecticide. It is available
as an emulsifiable concentrate and 25 percent wettable powder
for use as sprays and as a 1, 2 and 3 percent dust.

GUTHION
Guthion is an organic phosphate insecticide. It is available
as emulsifiable concentrate and 25 percent wettable powder for
use as spray and also as a 21/2 percent dust and 21/2 percent
granular.
DEMETON
Demeton, a systemic insecticide, is a phosphatic material
used principally for the control of aphids, mites and related in-
sects. It is available as a concentrate formulation containing 26.2
percent by weight of actual material. It should be handled and
used as recommended by manufacturer.

LIME-SULFUR
The concentrated commercial liquid lime-sulfur usually tests
about 330 on the Baume hydrometer. This material should
always be diluted. Lime-sulfur should never be used with soap
or with soap-oil emulsions without stabilizers.







Florida Agricultural Experiment Stations


COMBINED SPRAYS FOR INSECTS AND
DISEASE CONTROL
When desirable, the spray materials recommended for the
control of insects and diseases sometimes may be combined in
1 mixture and application, thus saving time and labor. The
spray schedule for combating pecan insects and diseases, if
carefully followed, will give commercial control of most of the
important insects and diseases. However, a general spray sched-
ule is not always the most satisfactory one for a particular or-
chard and the details of the control program should be worked
out to meet local conditions.

CONCENTRATE SPRAYING
Concentrate sprayers have not had a thorough trial for con-
trol of insects and diseases of pecans in the southeastern United
States. Although certain insects of pecans have been controlled
satisfactorily with concentrate sprayers, preliminary investiga-
tions indicate that this method of applying fungicides gave less
scab control than hydraulic sprayers. Where speed is a factor,
and if the orchard warrants more than 1 spray machine, alter-
nating the hydraulic and concentrate applications may result in
commercial control of pecan scab.
Because pecan scab is difficult to control under conditions
favorable for its development, even with hydraulic sprayers,
it is considered that concentrate sprayers for pecan disease con-
trol are still in the experimental stage and further work is'needed
before this method can be recommended for scab control.

HYDRAULIC SPRAY OUTFIT
Medium-sized portable spray outfits have been extensively
used for spraying pecan trees. Such machines may be equipped
with motors capable of developing 15 to 25 horsepower, or they
may be driven by power take-offs on tractors or trucks. Tanks
should hold at least 300 gallons of spray material. The machine
should have a pump capacity ranging from 25 to 35 gallons per
minute and be capable of maintaining a pressure of 400 to 600
pounds with the spray gun open. Machines of this type, under
average conditions, will spray trees from 40 to 60 feet high.
Since the operator should stand on top of the machine, a spray
gun that can be adjusted to produce both a wide-angled mist







Florida Agricultural Experiment Stations


COMBINED SPRAYS FOR INSECTS AND
DISEASE CONTROL
When desirable, the spray materials recommended for the
control of insects and diseases sometimes may be combined in
1 mixture and application, thus saving time and labor. The
spray schedule for combating pecan insects and diseases, if
carefully followed, will give commercial control of most of the
important insects and diseases. However, a general spray sched-
ule is not always the most satisfactory one for a particular or-
chard and the details of the control program should be worked
out to meet local conditions.

CONCENTRATE SPRAYING
Concentrate sprayers have not had a thorough trial for con-
trol of insects and diseases of pecans in the southeastern United
States. Although certain insects of pecans have been controlled
satisfactorily with concentrate sprayers, preliminary investiga-
tions indicate that this method of applying fungicides gave less
scab control than hydraulic sprayers. Where speed is a factor,
and if the orchard warrants more than 1 spray machine, alter-
nating the hydraulic and concentrate applications may result in
commercial control of pecan scab.
Because pecan scab is difficult to control under conditions
favorable for its development, even with hydraulic sprayers,
it is considered that concentrate sprayers for pecan disease con-
trol are still in the experimental stage and further work is'needed
before this method can be recommended for scab control.

HYDRAULIC SPRAY OUTFIT
Medium-sized portable spray outfits have been extensively
used for spraying pecan trees. Such machines may be equipped
with motors capable of developing 15 to 25 horsepower, or they
may be driven by power take-offs on tractors or trucks. Tanks
should hold at least 300 gallons of spray material. The machine
should have a pump capacity ranging from 25 to 35 gallons per
minute and be capable of maintaining a pressure of 400 to 600
pounds with the spray gun open. Machines of this type, under
average conditions, will spray trees from 40 to 60 feet high.
Since the operator should stand on top of the machine, a spray
gun that can be adjusted to produce both a wide-angled mist







Florida Agricultural Experiment Stations


COMBINED SPRAYS FOR INSECTS AND
DISEASE CONTROL
When desirable, the spray materials recommended for the
control of insects and diseases sometimes may be combined in
1 mixture and application, thus saving time and labor. The
spray schedule for combating pecan insects and diseases, if
carefully followed, will give commercial control of most of the
important insects and diseases. However, a general spray sched-
ule is not always the most satisfactory one for a particular or-
chard and the details of the control program should be worked
out to meet local conditions.

CONCENTRATE SPRAYING
Concentrate sprayers have not had a thorough trial for con-
trol of insects and diseases of pecans in the southeastern United
States. Although certain insects of pecans have been controlled
satisfactorily with concentrate sprayers, preliminary investiga-
tions indicate that this method of applying fungicides gave less
scab control than hydraulic sprayers. Where speed is a factor,
and if the orchard warrants more than 1 spray machine, alter-
nating the hydraulic and concentrate applications may result in
commercial control of pecan scab.
Because pecan scab is difficult to control under conditions
favorable for its development, even with hydraulic sprayers,
it is considered that concentrate sprayers for pecan disease con-
trol are still in the experimental stage and further work is'needed
before this method can be recommended for scab control.

HYDRAULIC SPRAY OUTFIT
Medium-sized portable spray outfits have been extensively
used for spraying pecan trees. Such machines may be equipped
with motors capable of developing 15 to 25 horsepower, or they
may be driven by power take-offs on tractors or trucks. Tanks
should hold at least 300 gallons of spray material. The machine
should have a pump capacity ranging from 25 to 35 gallons per
minute and be capable of maintaining a pressure of 400 to 600
pounds with the spray gun open. Machines of this type, under
average conditions, will spray trees from 40 to 60 feet high.
Since the operator should stand on top of the machine, a spray
gun that can be adjusted to produce both a wide-angled mist