Beetles Team With Insecticides To Control Apple Pests
One ofthe most important steps
for apple growers who are in
terested in improving or adopting
Integrated Pest Management
(IPM) practices this year is to
carefully plan their orchard
pesticide program before the
spring spraying season begins.
Although IPM in a broad sense
may involve special strategies for
controlling diseases, insects,
weeds and a variety of other or
chard pests, in the Mid-Atlantic
region IPM is primarily centered
around controlling the European
red mite and other harmful mite
species with the aid of beneficial
insects and mites.
Mite Predators
The key to developing a suc
cessful integrated mite control
program lies in orchard
management which is designed to
create a favorable environment for
beneficials. In most apple growing
regions throughout Delaware,
Maryland, Pennsylvania, New
Jersey, Virginia and West
Virginia, tin SMftorw »wrt—, a
lady beetle, serves as the cor
nerstone of IPM programs. From
May through late summer, the
small black beetles can be found in
nearly all commercial orchards
feeding on two-spotted spider
mites and European red mites. In
the spring and early summer, the
rust mite also serves as a food
source for the ladybird beetles as
they begin to reproduce and build
in number.
Tim White of Crop Management
Strategies, an agricultural con
sulting and research firm in
Hereford, Pennsylvania, notes that
while & mmctm is the number one
beneficial throughout most of the
mid-Atlantic region, a number of
other predators may also help to
controol mites and certain insect
pests.
Among those found in Penn
sylvania and neighboring states
are the predacious mite Amtfytikn
Mlteit (a key predator in
Michigan, New York and New
England), and the AaMMotos
mkkllmyzt, a midge which preys on
green apple aphid. Other
beneficial species include
predatory thrips which feed on
mites, as well lacewings which
attack a wide range of insect pests.
“While each Of these predators
plays a role in biological control,
the S. a—ct—i is by far the most
important beneficial in this part of
the country,” White says. “When a
grower wants to build a strong
IPM program, the first objective is
to develop an orchard environment
where the ladybird can survive
and flourish. Once you’ve
established a management
program that supports the
ladybird beetle, chances are good
that you’ll find one or more of these
other predators are. also present
and aiding in control of certain
insect pests.”
Selective Pesticides
Important
As White and other fruit
specialists point out, given the
right orchard conditions, the S.
pwrfiwi will soon multiply to the
point where it is capable of ef
fectively controlling mites with
little or no assistance from
miticides. In economic terms,
biological mite control can also
pay attractive dividends to the
grower by eliminating the need for
one or more miticide sprays during
the season. For each miticide
spray excluded, savings in
chemical costs alone often exceeds
$l5 per acre.
To ensure the survival of
predators throughout the growing
season, however, careful selection
of pesticides and timing of ap
plication are critical. For con
trolling most pests, this means that
organophosphate (OP) In
secticides are preferred over
pyrethroids and most carbamates.
This is particularly important
during the period between petal
fall and late summer when
predators are breeding and
building up to population level
sufficient to keep mites from
causing serious damage to the
trees.
According to Dr. Doug Pfeiffer,
extension entomologist at the
Virginia polytechnic University
Shenandoah Valley Research
Station at Steeles Tavern,
Virginia, growers who are in
terested in developing a strong
IPM program need to be especially
aware of the impact of pyrethroids
on beneficials.
“We encourage growers who are
interested in IPM strategies to
avoid applying pyrethroids in their
orchards, particularly after petal
fall,” Pfeiffer says. “Data from a
number of studies shows that mite
populations generally increase
their pyrethroid applications,
which we feel is due to the toxicity
of the chemicals to important
predators such as the $. pmctum. ’ ’
OP Resistance
For controlling most major
insect pests in IPM programs,
organophosphate (OP) in
secticides are generally recom
mended by universities in post
petal fall cover sprays. The
primary reason why many OP
insecticides fit well in IPM
programs is because predators
such as S. pmtetmm display a degree
of tolerance or resistance to these
chemicals.
In essence, this is due to the fact
that- for more than two decades,
many successive generations of
these predators have been exposed
Lancaster Fanning Saturday, April 11,1M7*09
to continuous application of the OP
compounds in commercial or
chards. As a result of this long
term exposure, selection for
tolerance has occurred. Today,
key predators such as the S. (nmc
tmi are relatively insensitive to
most commonly used OP
materials, including such in
secticides as Lorsban, Guthion,
Imidan and Penncap.
The newest of these OP
materials, Lorsban SOW in
secticide* has been extensively
evaluated in IPM situations over
the last four years by many
growers in the mid-Atlantic region,
as well as by university and ex
tension entomologists throughout
theU.S.
Dr. Pfeiffer notes that in
Virginia, as well as many neigh
boring states, Lorsban is
recommended for a variety of
The ladybird beetle, pictured here in its larval (left) and
adult forms, is cornerstone of most integrated pest
management programs used by Pennsylvania apple growers.
apple pests including codling
moth, San Jose Scale crawlers,
leafrollers, plum curculio and
others.
“Our experience with Lorsban
SOW thus far has shown that it fits
very well in IPM programs,”
Pfeiffer says. “It’s regarded as a
general or broad spectrum product
and is one of the few materials we
recommend quite frequently for
San Jose scale crawler sprays.”
Marshall Kuntz, a partner in the
tree fruit consulting firm of Rice
and Kuntz, which serves several
dozen growers in Adams County,
Pennsylvania, agrees that in
secticide selection and timing of
application are key factors in
protecting beneficials.
“In our experience, we’ve found
that sulfur, pyrethroids and car
bamate-type pesticides such as
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