Title: Trial insect management system for pecans
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Title: Trial insect management system for pecans
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Creator: Ball, J. C.
Publisher: Agricultural Research Center, IFAS, University of Florida
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AGRICULTURAL RESEARCH CENTER MONTICELLO
Monticello ARC Research Report 1978-3 May 22, 1978" -

JUN us eyi'8
TRIAL INSECT MANAGEMENT SYSTEM FOR PECANS
"Unil. of
J. C. Ball, L. A. Halsey and T. E. Crocker^ -" F.o.n"i


Rationale for Pest Management

Prior to the late 1940's the number and effectiveness of pesticides avail-
able to growers was limited. Because of this, treatments were keyed to the life-
cycle of the insects and their most vulnerable stage or period. The advent of
the "modern" organic pesticides, however, seemingly freed the grower from such
constraints on timing. The new chemicals such as DDT, dieldrin, parathion, etc.
were so effective and had such broad spectrum of activity that growers could apply
them at protracted intervals and still achieve unheard of control. In this
manner, timing for the pest became less important (critical) and it was expedient
to schedule sprays by the calendar to facilitate planning and efficiency of the
farm operation. Unfortunately, this ideal situation was not to last, terminated
by the natural resilience of biological systems. Pests developed resistance to
the chemicals and others, not previously important, became pests when their
natural enemies were killed by the pesticides. In response, growers began
applying pesticides at shorter intervals and higher rates. Resistance and
secondary pest outbreaks were hastened while costs increased and control decreased.
In a way we have come full circle. Because of increasing costs through
factors mentioned above, we once more must match treatments to the life cycle
of the pest and ideally only when the cost of treatment is justified by a greater
loss from damage. Preliminary trials in Alabama and Georgia on managing insect
pests in pecans, basing treatments on pest levels rather than calendar inter-
vals, have shown a reduction in spray cost without reduction in yield or quality.
Presently, we do not have economic thresholds for the pecan insects,
because information is lacking on the amount of damage done. The treatment
levels suggested are designed to give a large margin of safety. For the most
part, levels and sample size have been extracted from the Alabama and Georgia
programs. As our experience increases and more information is gathered, these
levels will probably be revised upward.

Brief Biology of Major Pests

Pecan Nut Casebearer: The nut casebearers overwinter as small larvae in
cocoons attached to buds of the pecan tree. In late winter and early spring
the larvae leave their cocoons and feed on buds and developing shoots. Adult
moths from this generation emerge in late April and May and egg laying coin-
cides with the time that young nuts first appear. The small flat eggs are laid
on the nuts near the blossom end."and upon hatching the larvae will feed on buds


1 Assistant Entomologist (ARC, Monticello),County.Extension Director (Jefferson
County), and Associate'Extension Horticulturist (Fruit Crops Department -
Gainesville), respectively.


L








before entering the nuts. Generally, only one egg is laid per cluster. This
is the most destructive generation because a single casebearer larva can destroy
several nuts or even the entire cluster. In later generations the nuts are
large enough so that a larva will complete its development in a single nut and
treatment is seldom required. The larvae (worms) are dark gray with a black
heads Damage is characteristic and easily recognized because of the mass of
borings and excrement held together on the outside of the nut by a loose mat
of silk.

Yellow Aphids: Yellow pecan aphids overwinter as eggs on the bark of the
pecan tree. Eggs hatch in the spring and the nymphs move-onto the foliage. As
the name implies, nymphs and adults are yellow in color. The youngest nymphs
are extremely small and easily overlooked. Feeding is confined to the leaves
and almost exclusively to the lower surface. Development is rapid and there
are many generations a year. There appear to be two population peaks a year:
one in late spring and early summer, another in late summer or fall. The
actual effect of yellow aphid feeding is unclear, but it does appear that
heavy populations can reduce nut size and quality. These aphids produce
copious amounts of honeydew, which, if not washed off by rains, support the
growth of a black, sooty-mold fungus. Sooty-mold does not harm the plant
directly, but by blocking light coming to the leaves, it reduces the plant's
ability to manufacture nutrients.

Hickory Shuckworm: The hickory shuckworm is principally a pest of the more
mature nut. Shuckworms overwinter as larvae and pupae in old shucks on the
ground and in the trees. Adult moths emerge in late winter and early spring
before there are nuts on the pecan trees. These adults fly to hickory and their
larvae feed in the hickory nuts and phylloxera galls. Adults from this genera-
tion move back to pecans. Larvae feed inside developing nuts and in the shuck
after the shell has hardened. Generally, larvae destroy few nuts in June, but
in mid summer heavy nut loss can occur. Before shell hardening, attacked nuts
drop from the trees. After the shell has hardened, feeding is confined to
the shuck which may result in poor kernel development and adhesion of the shuck,
which blackens the shell and makes removal difficult.

Black Aphid: The black pecan aphid, although present on the foliage
throughout most of the growing season, generally does not build up to damaging
levels until late summer and fall. Black aphids apparently secrete a toxin
that causes a yellow spot around the feeding site which gradually enlarges and
eventually turns brown. Enough spots will cause the leaflet to drop. Because
of the time of occurrence, the consequence of defoliation caused by black aphids
is greatest on the next year's crop, precluding adequate nutrient storage for
nut set. Like the yellow aphids, the youngest stage of the black aphid is
barely visible to the naked eye, considerably smaller than a pin head. The
nymphs are greenish brown and the adults are dark with prominent black tubercles.
Black aphids do not form large colonies but are found scattered on both upper
and lower leaf surface.

Pecan Weevil: Adult pecan weevils emerge from the soil in late summer
through fall in north Florida. Adults feed on the nuts, but eggs are not laid
until the shell has hardened and the kernel tissue begins to solidify. One to
several eggs will be laid in a single nut. The white, grub-like larvae feed
exclusively on the nut kernel. When the larvae have reached full development,
they chew a circular hole through the shell and enter the soil. Normally,
these larvae remain inactive in the soil until the second year when they change
to adults and the cycle starts again.









Sampling Program and Treatment Levels.


Pest Species


Saimn1p Si7P1


..- I I -I I


April July 1


Nut Casebearer


20 clusters per tree2
5-10% of trees in
small orchard.


Eggs found on 5%
of clusters.
Treat when majority
of eggs in red ring
stage.


Blacklight trap
2 lights per orchard.


Helps time egg sample
and treatment. 4 moths
per niqht.


Yellow Aphid


10 compound leaves
npr trpp3


30 aphids per com-
nnund rl if


July 1 October Hickory Shuckworm Blacklight trap 2 6 moths per night per
traps per orchard, trap.
Yellow Aphid 10 compound leaves 10 aphids per leaf.
per tree.
Black Aphid 10 compound leaves 1 aphid per leaf.
per tree.
Pecan Weevil Screen cages, burlap When weevils present
bands sticky and shells have
bands hardened.

Pecan cultivar and location in the orchard can effect the levels of a particular
pest species. Therefore sampling should take this into consideration. Divide
the orchard into quadrants and sample an equal number of trees from each quadrant.
Sample each variety, if possible, in proportion to their numbers in the orchard.
Mark the trees with flagging or other easily seen material at the beginning of
the season and sample the same trees throughout. Sampling should be conducted
twice a week.
2
2Completely circle tree, randomly selecting clusters that can be reached from the
ground. Clusters can be examined without removing from the tree.
3
Circle tree, randomly selecting leaves. Inspect lower leaf surface taking care
not to dislodge aphids.
4
Circle tree, randomly selecting leaves. Examine both upper and lower leaf surface.
To be done only in orchards known to have weevil problems. For weevil sampling,
select trees that have had heavy infestations. The grower should choose the
sampling technique that is easiest for him to work with see "Sampling Adult
Pecan Weevils" by W. W. Neel and M. Shepard. S. Coop. Ser. Bul. 208. 1976.


(Spray materials and rates can be found in: "Pecan Insect and Disease Recommen-
dations" by J. C. Ball and W. J. French. ARC, Monticello Res. Rept. BB1978-2.)


Time


-c i


Treatment L l





mov ?, 197"51 0 a $* 0







[il AGRICULTURAL RESEARCH CENTER MONTICELLO
Monticello, Florida

Monticello ARC Research Report 1978-4 July 26, 1978

COMMERCIAL PEACH AND NECTARINE VARIETY RECO EHU LIBRARY
C. P. Andrews and C. E. ArnoldOCT3 19
OCT 23 978

Commerical peach production in north Florida would F. psepsible without
varieties adaptable to our area. Peaches grown in north vtWf Ifif
volume shipments of the season. Yet, the number one problem affecting
industry is the lack of better adapted varieties. Peach and nectarine cultivars
currently recommended for north Florida range in chill requirements from 450 to
750 hours below 450F (70C). Another factor influencing this industry is the
earliness of fruit ripening. For maximum profits, peach and nectarine varieties
should ripen before those grown in the large production areas of Georgia, South
Carolina and California while fruit quality must be acceptable on northern
commerical markets.

Peach Variety Recommendations

Figure 1 illustrates the order and time of ripening of 14 peach varieties
in a normal season.- 'Camden' starts the season the last week in April while
'Loring' is the last cultivar ripening in mid to late June.
S'Camden' ripens in late April but fruit size has been small, averaging 1 3/4
inches in diameter or 55 grams. Fruit are yellow fleshed with a 60% exterior
red blush. Fruit are round with a prominent suture, clingstone with good firm-
ness and average flavor. 'Camden' is recommended for trial or limited plantings
only. Its chill requirement of 750 hours is considered marginal for north
Florida. Fruit should be thinned early and heavy.
'Springbrite' ripens in early May. Fruit size has been small to medium,
1 3/4 to 1 7/8 inch diameter (70 g.) with early and heavy thinning. Fruit are
attractive, having an 80% red blush, yellow flesh, round with a suture and tip
and semifree. It is recommended for north Florida having a chill requirement
of 650 hours but should be thinned properly.
'Springcrest' ripens in early May but fruit size has been small, 1 3/4 inch
diameter or 57 grams. Fruit have a 70% red blush, yellow flesh, round with a
tip and clingstone. 'Springcrest' has good firmness with average flavor. Quality
of many early varieties is not as high as those ripening later in the season.
'Springcrest' (700 hours) is recommended for trial planting but should be
thinned early and heavy to increase fruit size.
'Flordaking' ripens in early May with 'Springcrest'. Fruit are large, 2
to 2 1/4 inch diameter (100 grams). Fruit have a 70% light red blush, yellow
flesh, round with a suture and clingstone. 'Flordaking' should be planted on
warm sites since its chill requirement is 450 hours.

1 Assistant Horticulturist and Associate Horticulturist.
2 This research report was prepared in collaboration with T. E. Crocker,
Extension Horticulturist.









'June Gold' ripens in mid-May and is the leading variety grown in Florida.
Fruit are large, 2 to 2 1/4 inch diameter (105 grams), yellow fleshed and have
a 60% red blush. Fruit are round with a tip and have good firmness and flavor.
'June Gold' is recommended for north Florida with a chill requirement of 650
hours. ;t
'Maygold' ripens in late May with medium size fruit, 2 inch diameter (80
grams). Fruit are round with a tip, 50% red blush, yellow fleshed and clingstone.
'Maygold' is recommended for north Florida with a chill requirement of 650 hours.
'Rio Grande' ripens in early June with large, 2 to 2 1/4 inch (105 grams)
peaches. Fruit are round with a tip, yellow fleshed with a 60% red blush and
freestone.' 'Rio Grande' has good firmness and flavor and is recommended for
planting on warm sites in north Florida having a chill requirement of 450 hours.
'Suwannee' ripens in mid June and should end the commercial season. Fruit
are medium size, 1 7/8 to 2 inch diameter (75 grams) and freestone. Fruit have
a 60% red blush, yellow flesh, round with a suture with good firmness and excel-
lant flavor. 'Suwannee' is recommended for planting in north Florida with a
chill requirement of 650 hours.
'Harvester' ripens in mid June with 'Suwannee'. Fruit are medium size, 2
inch diameter (85 grams), yellow flesh and freestone. Fruit have a 70% red
blush, good firmness and flavor. 'Harvester' is recommended for trial planting
only with a marginal chill requirement of 750 hours.
Peach varieties included in this evaluation but currently not recommended
for north Florida are 'Springold', 'Bicentennial', 'Sunnyside', 'Fairway', and
'Loring'. Although 'Springold' is an early ripening cultivar, its chill require-
ment of 850 hours is considered high for north Florida. 'Bicentennial' also
ripens early in the season but fruit size has been small and it has a marginal
chill requirement. Both 'Sunnyside' and 'Fairway' are susceptible to bacterial
leaf spot and should not be planted where this disease is a problem. Because
of the late ripening period and marginal chill requirement, 'Loring' is not
recommended for commercial planting in north Florida.

Nectarine Variety Recommendations

Figure 2 shows the order and time of ripening of five nectarine varieties.
'ArmKing' is the first nectarine to ripen in early May while 'Sungold' ends the
season in late June.
'ArmKing' ripens in early May with large 2 to 2 1/4 inch diameter (100 grams)
fruit. Fruit have an 80% red exterior, yellow flesh and clingstone. 'ArmKing'
has only average flavor but earliness and size more than compensate for lack of
quality. 'ArmKing' requires 600 hours of chilling and is recommended for north
Florida.
'ArmQueen' ripens in mid-May, with small to medium size fruit, 1 7/8 inch
diameter (67 grams). Fruit are yellow fleshed, round with a suture and have good
firmness and flavor, 'ArmQueen' is recommended for trial planting in north
Florida with a chill requirement of 650 hours but should be thinned early and
heavy.
'Sunlite' ripens in mid to late May with round medium size fruit, 1 7/8
inch diameter (70 grams). Fruit have yellow flesh, 60% red blush and freestone.
'Sunlite' has medium firmness and good flavor and is recommended for planting on
warm sites having a chill requirement of 450 hours,
Nectarine varieties included in this evaluation but currently not recom-
mended for commerical production in north Florida are 'Sunrich' and 'Sungold'.
In recent years, they have not competed favorably with California nectarines.
'Sunrich' and 'Sungold' are still recommended for homeowner and pick-your-own
operations.


k -








Figure 1. Normal ripening sequence of peach
Agricultural Research Center, Monticello,


Figure 2, Normal
at Agricultural


ripening
Research


cultivars at


sequence of nectarine cultivars
Center, Monticello,


April May June
1 10 20 1 10 20 1 10 20

Camden
Springold
Springbrite
Springcrest
Bicentennial
Flordaking
June Gold
Maygold
Sunnyside
Fairway
Rio Grande
Suwannee
Harvester
Loring


May June
1 10 20 1 10 20

ArmKing
ArmQueen
Sunlite
Sunrich
Sungold


. a






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