Insects and Nematodes of Nut Trees

Michigan State University Extension, Home Horticulture - 03900042, 01/01/96

A small number of insects affect nut trees from time to time, and the greatest number
of these are indirect pests.
These pests attack the foliage and other parts of nut trees, taxing tree vigor and occasionally reducing yield. However annoying they are, the control of indirect pests
is only necessary when they reach high numbers.

Some examples of indirect pests include: The walnut caterpillar (Datana integerrima). The most serious indirect pest; it can completely defoliate a full-sized tree in a
short period of time. Several other indirect pests are seldom as serious: Bark beetles, round headed borers and twig borers are examples of these.

The key to insect control is timeliness. It is necessary to inspect trees regularly, at least twice a week in the early part of the growing season. It is important to learn to
identify the important pests of nut trees and to be able to assess the type and severity of damage.

PEST SITE OF DAMAGE PESTICIDES

--------------------------------------
- -
Aphids, - branch tips; - malathion;
includes - underside of - diazinon
gall mak-- foliage -
ers - -
- -
Canker- - Foliage - Sevin
worms - -(cararyl)B.t
- -
Codling - Husk of green - Sevin,
moth - nuts, causing - diazinon
- early drop -
- -
June - Foliage - Sevin,
beetles - - diazinon
- - methoxychlor
- -
Mites - Causes hairy - malathion
- distortion of -
- leaf periole -
- -
Walnut - Foliage - Sevin, B.t,
cater- - - diazinon,
pillar - - malathion
- -
Walnut - Green husk - Sevin
husk - - diazinon
maggot - -
- -
Fall web-- Foliage - Sevin
worm - - B.t.
- -
- -
PEST TIME OF APPLICATION ALTERNATIVES
----------------------------------------------------------
Aphids, - Several generations:- High pressure
includes - apply when needed, - water spray to
gall mak-- beginning in May - dislodge aphids
ers - - dormant.(oils
- - in Apr. or Sept
- -
Canker- - Apply to larvae in - Put sticky
worms - May - bands around
- - trunk in Sept.
- - and renew in
- - late Feb.
- -
Codling - Apply to larvae in - Note: Control
moth - May and late July to- should be timed
- early August - to egg laying
- - of adults.
- -
June - Apply to adults in -
beetles - late June through -
- early August -
- -
Mites - Apply throughout the- Dormant oils in
- summer for several - April
- generations -
- -
Walnut - ,Apply beginning late-
cater- - June to larvae -
pillar - -
- -
Walnut - Apply in late July - Nuts are sound
husk - through Sept. for - despite stain
maggot - adults - from mush husks
- - control may not
- - be necessary
- - for home-grown
- - nuts
- -
Fall web-- Apply to larvae, - Control is
worm - late July-Sept. - unnecessary.
- - No damage to
- - crop or tree
- - vigor. Remove
- - webs.

SOURCE

Insect and Nematode Special Report
July 1980 80-19 “Insect Pests of Nut Trees”
Prepared by: Gary A. Dunn,
Department of Entomology, MSU
Cooperative Extension Service
Michigan State University

Visuals associated with this text.
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Bark beetle damage - 42K
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