Agriculture Reference
In-Depth Information
ing July and August. Heavy feeding can weaken the trees; insecticidal soap,
spinosad products, and Surround should provide good control.
Pear Leafcurling Midge
Pear leafcurling midge is an introduced European pest that attacks only pear
trees. The adults are tiny flies that pupate underground and emerge at about
bloom time and lay their eggs on new, folded leaves. The grub-like larvae
hatch in 3 to 5 days and feed within the folded leaves, with as many as 30
grubs per leaf. The feeding causes the leaves to remain tightly folded, pro-
tecting the grubs from predators.
When they mature, the grubs chew out of the leaves, fall to the ground,
and pupate. Depending on the growing region, you may experience four to
five or more generations per year. Mature trees tolerate the damage, and
control is seldom needed in established orchards. Newly planted pear trees in
orchards and nursery trees can be severely stunted. In conventional orchar-
ds, organophosphate pesticides are used to control the pest, but recommend-
ations for organic control in North America are lacking. In New Zealand, the
closely related apple leafcurling midge is effectively controlled by parasit-
ic wasps, pirate bugs, and earwigs. Where the midge is a problem, consider
applications of neem and spinosad products at petal fall and focus on main-
taining healthy populations of beneficial insects.
Boring Insects
Many insect pests damage fruit trees by boring into trunks, branches, and
twigs, including ambrosia beetle, American plum borer, dogwood borer, lesser
peachtree borer, Pacific flatheaded borer, peachtree borer, peach twig borer,
and shothole borer.
Ambrosia Beetle and Shothole Borer
These are general terms that include species that range from the southeast-
ern United States to the Pacific Northwest and into Canada. Other names in-
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