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pyrethroid insecticide is discouraged. Pyrethroids are
toxic to various predator insects. Agrimek,Mitac,
Provado, and Pyramite are effective during the foliar
season.
Pear Rust Mite.Rust mite feeding results in a
russeting on the fruit. If rust mites were troublesome the
previous season, start controls at green cluster bud and
repeat at petal fall. Thorough spray coverage is essential
for satisfactory control of mites. Concentrate or alternate
row sprays generally result in inadequate control due to
minimal spray deposit. A pre-bloom application of
Morestan will supress pear rust mites as will most post-
bloom miticides. Do not apply Vydate within 30 days of
full bloom or fruit thinning may occur.
Plum Curculio. Generally, overwintering adults
(weevils) make their first appearance in orchards during
bloom. Cool weather slows down their emergence from
overwintering sites while warm spells (70oF and above)
can produce large numbers of weevils suddenly in trees.
There is one generation each year in New Jersey. The
petal fall, shuck split, shuck fall, first and second cover
sprays are most critical for control. Insecticides labeled for
plum curculio control are Ambush/Pounce, Asana,
Guthion, Imidan, and Penncap M. Also labeled but less
effective are malathion and Sevin.
Rosy Apple Aphid (RAA) and Apple/Spirea
Aphids. Overwintered rosy apple aphid eggs commence
hatching in early spring, and the peak hatch occurs during
the green-tip period. Hatch is generally completed by
1/2-inch green. Superior oil has little effect on aphid
nymphs but will suffocate embryos in unhatched eggs.
Lorsban, Diazinon, and Supracide are all effective when
combined with oil and applied at green tip to 1/2-inch
green. Phosphamidon, applied prepink, has also provided
control.. For best RAA control, start the control program
early. Donít wait until petal fall. Apple aphids are
controlled by the same aphicides at the same times
mentioned above. Summer sprays to control apple aphids
often do more harm than good because two commonly
used aphicides, Lannate and Thiodan, are moderately to
highly toxic to mite predators. Dimethoate is a better
choice for apple aphid control since it is less toxic to mite
predators. Control of aphids is suggested only when 50
percent or more of the terminals are infested with visible
colonies. Removal of sucker growth aids control.
San Jose Scale. This pest seems to be more
troublesome every year and difficult to control once the
immature stages (crawlers) and, particularly adult scales,
are noted on twigs and limbs during the growing season.
A dormant application of superior oil is still the best way
to control this pest and is recommended in problem
blocks. Best results are obtained when oil is applied in at
least 200 gallons of spray per mature acre. An organo-
phosporous spray added to oil aids in control. For
postbloom scale control, Guthion and carbaryl (Sevin),
are labeled. Penncap-M is labeled for postbloom crawler
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control.
Spotted Tentiform Leafminer. This insect has
developed resistance to Guthion, Imidan, Penncap-M, and
Sevin. In problem orchards, control before bloom is most
important. The insecticides Ambush, Asana, Pounce,
and Carzol are all effective adulticides when applied
during the tight cluster period before egg hatch. Vydate
or Provado applied at Pink, controls developing
leafminers within the leaves. Thiodan, at pink and again
at petal fall, has also provided commercial control.
Agrimek plus a penetrant (oil or organosilicone penetrant)
is very effective if applied before leaves harden. If
necessary, the best time to control the second brood is in
late June to mid-July, when there is an average of 0.5 to 1
sap-feeding mines per leaf. Sap-feeding mines are made
by the young sap-feeding larvae and are only seen from the
bottom side of the leaf and tissue feeder mines can be seen
from the tops of leaves. The third brood should be treated
if there is an average of 2 to 3 or more total mines per leaf.
The fourth brood should only be treated as an emergency
when previous generations have not been controlled.
Premature fruit drop can occur when there is an average of
10 or more mines per leaf, or leafminer feeding has been
accompanied by heavy mite pressure or leafhopper
activity.
Thrips.Several species of thrips can damage tree
fruit. The Western flowers thrips can damage apples
during bloom and cause scaring or dimpling of the fruit.
On nectarine and peach, early season feeding damage can
result in russetted fruit while late season damage takes on
a silvering appearance. Cold, wet springs are not
favorable for this pest because it delays development, and
heavy rains can actually kill these frail insects. Mowing
ground cover during bloom and harvest should be avoided
to prevent thrips from leaving the ground cover for the
fruit. Also, eliminating flowering weeds in the orchard
should prevent thrips populations from increasing and
subsequent movement to the crop.
Tufted Apple Bud Moth and Variegated
Leafroller. These insects have similar life histories,
habits, and damage. In New Jersey, tufted apple bud
moth usually outnumbers variegated leafroller but both
may be found in the same orchard. There are two
generations per year. Adults generally begin flying and
laying eggs from about mid-June to mid-July and from
about mid-August through mid-September. In recent
years, most damage has come from the second generation
of moths because either spraying has stopped, fruit is
tightly clustered, insufficient spray volume was used, or
because of resistance development. Damage appears as a
ìshotgunî type of scarring on the upper and side surfaces of
the fruit. Heavier crops are most likely to sustain
damage. For best results, increase spray volume per acre
and thin to remove fruit clusters. Lannate or Penncap-M,
together or in combination with Guthion, (all at reduced
rates) gives the best control. The B.t.íshave also
provided excellent control in New Jersey.
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