COOPERATIVE EXTENSION WORK IN
AGRICULTURE AND HOME ECONOMICS
(Acts of May 8 and June 30, 1914)
Agricultural Extension Service, University of Florida,
Florida State University and
United States Department of Agriculture, Cooperating
M. O. Watkins, Director
CONTROL OF MINOR PESTS
OF COMMERCIAL CITRUS
James E. Brogdon
Fred P. Lawrence
Young citrus foliage severely curled by
There are minor problems of commercial citrus
which may become major in certain areas or
groves. Because of lack of space, controls for
these are not always included in the Citrus Bet-
ter Fruit Program Spray and Dust Schedule. This
circular will serve as a supplement to that spray
and dust schedule which is revised annually.
Some of the pests discussed in this circular
occur so sporadically that research workers have
AGRICULTURAL EXTENSION SERVICE
not been able to obtain enough experimental
evidence to make positive recommendations in all
cases. Controls given represent the best sug-
gestions currently available, and may need to be
amended as more information is obtained.
Aphids may occur in sufficient numbers to
cause severe curling of new foliage with resultant
stunting of twigs. While trees of all ages may be
attacked, control measures are warranted only
for young or top-worked trees (since the propor-
tion of new growth to old is much higher than in
mature trees) and occasionally Temple orange
and tangerine trees.
Winged and non-winged adult aphids and some young
For control spot treat early before infestations
become general. If aphid populations become gen-
eral, spray or dust all of the grove. Dust in calm
weather only. A 3 to 4 fo nicotine dust, or a spray
containing 1 pint of nicotine sulfate per 100 gal-
lons, will kill aphids. A spreader is recommended
with the spray. Other materials with aphidicidal
properties include malathion, parathion, deme-
ton (Systox), TEPP tetraethyll pyrophosphate)
and lindane. Use according to manufacturer's re-
commendations and precautions. After a large
percentage of leaves are curled or new growth is
nearly mature,-control is not practicable.
Several kinds of ants may be found in citrus
;roves. A leaf-cutting ant is one of the destruc-
;ive species. It cuts small pieces from the leaves
Ind carries them into its nest, which may be
located by following the stream of ants to the
:rescent-shaped mound formed by the colony.
This ant is not particularly destructive to large
resbut can kill young trees by defoliating each
lush of growth as it appears. A small black ant
vilalso feed on the bark of top-worked and small
On occasion a species commonly known as the
itle fire ant may be a severe pest, particularly
long the east coast, to workers during picking
nd pruning operations. The little fire ant can
sobe destructive to young and top-worked trees
y feeding on the leaves and young twigs.
Control: In groves where the little fire ant
uterferes with picking or pruning, spray pri-
narilyI the ground under trees as well as the trunk
nd larger branches at least 2 weeks before pick-
ng with 1 pound of 50qb chlordane wettable pow-
er per 100 gallons of water. Parathion applied
or scale control will control the little fire ant.
Ants nesting around the base of a tree may be
:ildby applying chlordane, aldrin, heptachlor
rdieldrin as a dust, spray or granules to the ant
ilsand soil around the base of the tree. Large
resmay be treated by applying heptachlor or
ieldrin granules at the rate of 2 pounds active
ngedent (20 pounds of 100% granules) per acre.
material should be broadcast evenly over the
oil surface with a hand seeder or similar equip-
nent. These insecticides can be applied also in
eriiesat the same rate of active ingredient.
leptachlor is cleared only for soil application.
At least 3 kinds of bagworms have been found
>y Muma on citrus in Florida. These caterpillars
instruct cone-shaped bags for shelters, using
mall sticks and bits of leaves fastened together
vih silk. They live inside the bags and carry
them around as they
feed. Their feeding in-
jury to fruit is similar
to damage caused by
Grasshoppers and katy-
dids, but the wounds
are not as deep.
Control: Cryolite is
suggest d, 1 to ll%
pounds of 50%/ dust per
tree (depending upon
size). As a spray use
3 pounds of 90% cryolite
wettable powder per 100
'gallons of water to be
applied so as to obtain
general outside coverage
of the tree. The addi-
tion of 2 quarts of an
emulsive oil per 100
gallons will aid in stick-
Case of the bagworm
(twice natural size). ing the cryolite.
Fuller's rose beetle, gray-brown in color and
1% to 1/ inch in length, and the citrus root beetle,
blue-green in color and Yz to 3Q inch in length,
may occur in sufficient numbers to cause severe
injury to both roots and foliage of all varieties of
citrus. Injury from these pests has been noted
most commonly on the Florida east coast. Grow-
ers should familiarize themselves with these in-
sects and the injury symptoms of both the larva
and adult stages.
Injury by the larval stage is by far more ser-
ious than injury by the adult stage. The legless
white larvae of both species eat canal-like chan-
nels in the root cortex. This injury is usually
more prevalent on the under side of lateral roots,
although where high populations occur many pri-
mary roots may be girdled near the main trunk
root. Adult injury to leaves typically appears as
notches cut out along the leaf margin. Injury is
usually more prevalent on the lower 6 feet of trees
and on leaves of sprouts near the main trunk.
Adults also feed on small fruit during and shortly
Citrus roots (below) damaged by larvae (left above)
of Fuller's rose beetle (adults shown center above--about
natural size). Right above, citrus root weevil (enlarged
Control.-Satisfactory results can be obtained
by mixing and applying granular formulations
of alcdrin, chlordane, dieldrin or heptachlor with
fertilizer at 2.5 to 5 pounds of active ingredient
per acre. However, dieldrin has given best and
most consistent control. A 2.5-pound-per-acre ap-
plication (of active ingredient) in fall and another
in spring result in a more even distribution of the
pesticides than a single application of 5 pounds
In addition to soil treatment, weed control by
frequent mowing, chopping or cultivation, or a
combination of these cultural practices, results
in better control than where weeds are allowed
to come in contact with trees.
Black scale is ordinarily controlled by natural
enemies, but becomes important in some groves
during certain years. Mature scales are raised
and have a pattern resembling the letter "H"
on their backs. Young stages feed on leaves and
green twigs; older stages feed on wood, especial-
ly on stems of fruit. There are 2 generations
Control after eggs have hatched with 1.3%/
oil emulsion spray or parathion at 1.7 pounds of
15%j wettable powder per 100 gallons of water.
Black scale, much enlarged.
COTTONY CUSHION SCALE
Cottony cushion scale is rarely of economic im-
portance except in young groves and nurseries.
The mature female is conspicuous because of her
fluted white egg sac. The Vedalia ladybeetle is
a very effective predator.
When chemical control is necessary, apply a
spray containing 2 pounds of 15ro parathion wet-
table powder or 4 to 5 pounds of 25%/' malathion
wettable powder per 100 gallons of water.
Grasshoppers frequently become numerous on
the cover crop in citrus groves during late sum-
mer and in the fall. Occasionally young trees
are completely defoliated and older groves sev-
erely damaged. Most injury occurs after the
cover crop is chopped or disked, thereby reduc-
ing the amount of available food and causing the
grasshoppers to migrate to the trees. Because of
this, growers should be prepared to dust or spray
immediately following the first chopping or disk-
iilg of dense cover crops. This has resulted in
better control than applying the spray or dust
to a standing cover crop. Cover crops should not
Heavy infestation of cottony cushion scale on young
citrus twig. Young scales shown on leaf.
be chopped or disked where grasshoppers are num-
erous unless insecticidal control is planned.
Control.--Parathion at 0.45 pound active in-
gredient (3 pounds 15%0 wettable powder) per
acre will give a quick kill that is often sufficient.
If grasshoppers are migrating into the grove
from other areas, control is only temporary.
Aldrin and dieldrin are 2 of the most effective
insecticides for control of grasshoppers which
attack citrus. However, because infestations have
been infrequent, these materials have not been
tested on citrus in Florida. From experiments
conducted against the same grasshoppers on
other crops, these materials are suggested at the
following rates per acre (in enough water to give
only general outside tree coverage) : (1) 1 pound
25%0 aldrin wettable powder or 1 pint 23%0 aldrin
emulsifiable concentrate; (2) 4i pound 2546
dieldrin wettable powder or 2/3 pint 18.5%~ diel-
drin emulsifiable concentrate.
Dusts containing 2Ya% aldrin or 1%%r diel-
drin at 10 to 15 pounds per acre can be used.
Toxaphene at 3 to 4 pounds active ingredient
per acre as a spray or dust is effective.
Because of the feeding habits of grasshoppers,
only general outside tree coverage is needed for
effective control. Air blast sprayers may be
pulled at 2 to 3 miles per hour and nozzles may
be arranged to apply most of the spray to the
lower 2/3 of the tree. As little as 50 to 100 gal-
lons of spray may be used per acre.
For information on control by special cultiva-
tion practices, see Fla. Agr. Exp. Sta. Bulletin
496, available from your County Agent.
Katydids are frequently seen in citrus groves,
but the damage they do is usually small. Oc-
casionally, on young trees, the broad-winged
katydid causes severe defoliation. A second type
of injury, causing the big fruit scar commonly
called katydid injury, may result from their feed-
ing on young fruit, although other kinds of in-
sects may also cause this damage.
Control.--The same chemicals and treatment
used to control grasshoppers are effective against
Mealybugs have a segmented body which is
covered with mealy white wax. They are most
common during spring and early summer, but
are frequently found during winter in tree
crotches and under loose bark. Mealybugs may be-
come so numerous following fruit set that their
feeding under the button of young fruit may
cause fruit to drop. They also collect in clusters
Mealybugs (natural size) on fruit.
For control, spray early post-bloom or before
the young fruit grows against the calyx, using
15fo parathion wettable powder at 1.7 pounds
or 25% malathion wettable powder at 4 to 5
pounds per 100 gallons of water. Dormant sprays
are effective in preventing a spring build-up of
The orange dog is often a pest of young citrus
trees. As an adult, the species is a large black
and yellow butterfly. The larva is an ugly brown
and white caterpillar which grows to a length of
11/2 to 2 inches. During the summer and early
fall these caterpillars may be quite destructive
on young trees.
Control.--Pick larvae off nursery stock and
young trees by hand. Parathion at 2 pounds 15%
wettable powder per 100 gallons appears to be ef-
fective, especially against the smaller ones.
Cryolite as for bagworms can be used.
Full-grown orange dog larva feeding on citrus foliage.
Plant bugs, or stink bugs, puncture the rind
of fruit, often causing them to drop. They may
cause considerable damage to all varieties of
citrus but injury is most common on tangerines
and early and mid-season oranges. Plant bugs
move to mature or nearly mature fruit from host
plants in or near the grove, particularly when the
cover crop is chopped or is beginning to dry up
or harden. Pods of leguminous cover crops, such
as beggarweed and crotalaria, are attractive to
these pests and often induce heavy infestations.
Control.--Plant bugs can be killed with a spray
containing 1.7 pounds 15%/ parathion wettable
powder per 100 gallons of water. Thorough cover-
average of only the outside or peripheral parts
of the tree should be adequate. Therefore, the
sprayer can be pulled through the grove at faster
than usual speed. Dusts containing 1%j para-
thion at 50 pounds per acre can be used. Chlor-
dane and toxaphene also are effective, but re-
quire a longer waiting period between application
and picking than parathion.
Cultural practices that will aid in reducing the
plant bug problems are discussed in Exp. Sta.
Bulletin 591, available from your County Agent.
Several species of small beetles, commonly
referred to as shot-hole borers, sometimes make
holes about the size of a pinhead in the bark and
sapwood of trees which have been weakened from
some cause such as lightning or high water. Since
shot-hole borers are secondary and are important
primarily in hastening the death of a weakened
tree, control measures may not save infested
trees. However, if infested trees are detected
early, control measures should be applied.
Control.--Weakened trees should be cultivated
and fertilized to stimulate vigorous growth. Lin-
dane applied to the wood at the rate of 2 pounds
25%0 wettable powder per 100 gallons of water
will aid in protecting uninfested weakened trees,
and may be of value when applied immediately
after trees become infested. Lindane should not
be applied to fruit.
Tree showing shot hole borer injury.
refuse in crotch.
This scale is a serious pest in parts of Orange,
Seminole and Volusia counties. Male scales are
conspicuous because of their elongated white cov-
ering, while females are difficult to see against
the tree bark. The scales are largely confined to
the trunk and large limbs, but sometimes infest
the leaves and fruit.
For control, spray thoroughly, especially the
trunk and larger limbs, with 15%r parathion wet-
table powder at 1.7 pounds per 100 gallons water
or a 1.3%0 oil emulsion spray. Parathion is more
effective than oil. A mixture of oil (0.7%) plus
1 pound of 15%0 parathion wettable powder per
100 gallons of water is very effective.
Soft brown scale (about natural size).
SOFT BROWN SCALE
Soft brown or turtle back scale commonly infest
young twigs and often gather along the midrib
of the leaf. Females give birth to live crawlers.
There are several generations a year. This pest
is highly parasited by tiny wasp-like insects and
rarely becomes numerous except on young trees
in a newly planted grove or in a nursery.
When chemical control is necessary, apply a
spray containing 3 pounds of 25% malathion wet-
table powder per 100 gallons water or a 1.3%i'
oil emulsion spray. A mixture of oil (0.7 ) plus
3 pounds of 25% malathion wettable powder per
100 gallons is excellent. Parathion is not effee-
tive against this pest.
Sooty mold grows on honeydew, a substance ex-
creted by whiteflies, soft brown scale, black scale,
cottony cushion scale, mealybugs and aphids. It
is not parasitic on the leaves, twigs or fruit.
Sooty mold on grapefruit.
However, large quantities may prevent sunlight
from reaching leaves to an extent that will in-
terfere! with normal growth.
Control sooty mold by controlling the above
insects which excrete honeydew.
Termites may girdle trees that are banked.
Do not bank trees with soil containing roots,
chips, paper, weeds and similar materials. Dam-
age may be prevented by treating the area to be
banked with a small amount (about 1Q cup) of
an insecticide powder and by adding another 1/4
cup to the mound when the bank is half com-
pleted. Dusts containing 5%0 chlordane, 21%% al-
drin, 21%% heptachlor or 1% O/o dieldrin may be
be used for this purpose.
Whiteflies, which infest the lower surfaces
of young leaves where they lay eggs and the lar-
vae or young excrete honeydew, are major pests
of citrus. However, few, if any, growers apply
insecticides for the control of these pests alone.
Peak broods of whiteflies generally occur during
March-April, June-July and September-October.
These are also the periods when young Florida
red and purple scales are most numerous. The
sprays applied for control of scales usually give
effective control of whiteflies.
Cloudy winged whiteflies on a citrus leaf.
Brown rot, which causes a rotting of fruits on
the tree, occurs mainly in coastal areas. The dis-
ease develops on early and mid-season varieties
in late summer and early fall, during prolonged
periods of cloudy, ramny weather.
Control can be obtained by spraying the lower
6 feet of the canopy with neutral copper- using
0.38 pound of metallic content per 100 gallons.
(Examples: 0.7 lb. of 52-56%0 or 0.5 lb. of 75%0
copper.) Apply the spray about ,the middle of
August in areas where the disease has been
troublesome in the past. In areas where brown
rot is only an occasional problem, spraying may
be deferred until immediately after the first ap-
pearance of affected fruits. Chopping of cover
crops, hedging of trees and lifting of tree skirts
will improve ventilation and reduce the likeli-
hood of infection.
Leprosis or nailhead rust on twigs and fruit.
Leprosis, or nailhead rust, due to the feeding
of brevipalpus mites, affects fruit, leaves and
twigs. Control by a single yearly spraying with
10 pounds of wettable sulfur per 100 gallons of
water applied just before the spring flush of
growth or during the post-bloom period.
Lichens frequently occur on trunks, branches,
twigs and leaves of citrus trees, and are some-
times mistaken for injurious pests by those un-
familiar with them. As a rule, lichens live super-
ficially and obtain food from the air and from
dead bark on which they grow. Lichens are con-
sidered harmless as far as direct injury produced
by their growth is concerned, but they detract
from the appearance of trees.
Lichens can be controlled by spraying affected
parts with bordeaux mixture (5-5-100). For best
control, spray wl~en lichens are dry.
Spanish moss Jtends to collect in citrus trees
that are not on a regular spray program. Effective
control can be ac~tieved by spraying the trees with
6-3-100 bordeaux mixture, being sure that the
spray penetrates the moss. This will not cause the
moss to drop fr m the trees immediately, but
will kill it and in time it will decompose and fall.
Space in this circular does not permit discus-
sion on all minor pests that may be found in
citrus groves. more detailed information on
these and other minor pests of citrus, see Agric-
ultural Experiment Station Bulletin 591, Insects
and Mites Found on Florida Citrus, and Bulletin
587, Ha~ndbook of Citrus Diseases in Florida, and
Agricultural Extension Service Circular 137, In-
sects and Mites of Florida Citrus.
RESIDUES AND TOLERANCES
The U. S. Food and Drug Administration has
established tolerances on amounts of certain pes-
ticide residues that can remain on citrus fruits.
Chemicals discussed in this circular which are
exempted from a tolerance include, sulfur, copper
and oil emulsion when applied before harvest.
Tolerances and waiting periods as of February,
1, 1960, for materials recommended in this cir-
cular for application to citrus trees follow:
a 8 piRegistered for Use on
Alri 0.25 30 XXXXX
Chlordane 0.3 t * * * X
Cryolite 7 (combined NTL * * * X
Dieldrin 0.25 30 XX XX X
Lindane 10 $ * * * X
Malathion 3 7 X XX X XX
Nicotine 2 3 * * * X
Parathion 1 14 * * * X
Systox 0.75 21 XX X
TEPP 0.0 3 **X
Toxaphene 7 30 * * * X
t Not established as of February 1, 1960, for application to fruit.
Wait at least 14 days when applied as directed for control of little
$ Do not apply after fruit begins to form.
NTL means No Time Limitation (when applied as directed).
Interpreted from FDA and USDA terminology "citrus fruits".
Read the labels on all pesticide packages and
observe all precautions.
Special Precautions when Using Paratho
Demeton (Systox) or TEPP. When mixingan
applying sprays, wear an approved chemical cart
ridge respirator and protective clothing. Wea
long sleeves, a washable rain hat, and NATUA
rubber boots and gloves.
Change to clean clothing each day, or often
if garments are wet with spray. If a liquid fo
mulation is spilled on the garments remove a
once and bathe. Take a thorough bath as soon a
the work day is finished.
Wash hands before eating or smoking.
Burn empty paper containers, but avoid smoke
crush and bury glass containers; punch holes i
metal containers and junk in safe place. D
NOT REUSE CONTAINERS. Wash spray equi
ment daily to avoid hazardous accumulations.
Spray crews regularly using these mateil
should receive cholinesterase tests before spray
ing begins and at 10-day intervals thereafter.
Operations involving contact with the te
such as pruning, should not be carried out witi
7 days of spraying with parathion or 3 days witl
Parathion or other highly toxic pesticide
should be kept in locked storage and never
removed from the spray job.
Prepared in cooperation with the Florida CitrusCo
mission; Florida Citrus Experiment Station: Florida Agr
cultural Experiment Station: College of Agricultr
University of Florida; State Plant Board of Florida; Flo1
ida State Horticultural Society; U. S. Denartmento
Agriculture. Agricultural Research Service. Horticultr
Crops Research Branch and Entomology~ Research Dv
sion: professional consultants and commercial im
Section on beetles prepared by Dr. J. R. King, India
River Field Laboratory.
Photographs of mealybugs and soft brown scale
USDA Fruit Insects Laboratory, Orlando.
The use of trade names in this publication is solely fo
the purposes of providing specific information. It is n
a guarantee or warranty of the products named and do
not signify that they are approved to the exclusion o
others of suitable composition.