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Walnut
Year-Round IPM Program
(Reviewed 12/07, updated 12/07)
These practices are recommended for a monitoring-based IPM
program that reduces water and air quality problems related
to pesticide use. Links take you to information on how to monitor,
forms to use, and management practices.
Track your progress through the year with the annual
checklist form. This program covers the major pests
of walnuts; information on additional pests is included in the
Walnut Pest Management Guideline.
Water quality becomes impaired when pesticides
move off-site and into water. Air quality becomes impaired when
volatile organic compounds move into the atmosphere. Each time
a pesticide application is considered, review the Pesticide
Application Checklist at
the bottom of this page for information on how to minimize air
and water quality problems.
| What should you be doing during this time? |
Manage orchard
floor vegetation.
- Continue postharvest weed assessment
in late fall to identify those that were not controlled
by fall treatment.
- Keep records (example winter
weed survey form—
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Assess mummy
nut levels on the ground and in trees for navel orangeworm management. |
Look for scale
pests and mites and evidence of parasitism.
- Examine
scaffolds, limbs, branches, spurs and prunings, for scale
pests and European red mite eggs.
- Note areas of concern
for possible treatment**.
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Other pests you may see:
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Delayed-dormant activities |
| What should you be doing
during this time? |
If a significant number of mummy nuts are
still on trees or on the ground at the end of February:
- Remove mummy nuts from trees before mid-March.
- Flail mow to destroy mummy nuts and remove huller
waste materials.
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Mow ground cover before bloom. |
If dormant scale and mite monitoring indicated need,
treat according to PMGs:
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Look for the following pests if they have been a problem
in the past:
Treat** if needed according to PMGs. |
Manage squirrels before
April, if needed. |
Budbreak through bloom activities |
In-season activities (nut development
period) |
| What should you be doing during this time? |
If conditions favor walnut
blight development:
- Treat** according to PMG if rainy conditions continue
beyond bloom.
- Or use the Xanthocast model to determine
the need for and timing of blight sprays.
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Maintain codling moth management program.
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If dormant monitoring indicated infestations of walnut
scale, monitor for crawlers.
- Manage
if needed according to PMG.
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Begin examining leaves for aphids.
- Look for aphids, aphid mummies, and natural enemies.
- Manage
if needed according to PMG.
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Take leaf samples in July for nutrition analysis. |
Start monitoring for webspinning
mites when the weather warms up, once per week through
August.
- Keep records.
- Manage
if needed according to PMG.
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Assess weeds in late
spring and identify those not controlled by fall/winter
treatment.
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Manage
weeds in rows with preemergent
or postemergent herbicides** or nonchemically in
organic orchards. Manage weeds
in row
middles. |
Monitor for walnut husk fly.
- Set out supercharged walnut husk fly traps by June
1 in coastal areas and by June 15 in inland areas and
check traps at least twice a week.
- If using GF120
bait sprays, apply** at first fly catch and use
only in orchards with low populations.
- Keep records (example walnut
husk fly monitoring form.
If using insecticide and bait
sprays:
- Treat** according to PMG when there is
a sudden increase in trap catches, or when
the first egg is
detected.
- Don't treat within 3 weeks
of harvest.
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Consider using a plant growth
regulator to hasten husk
split for early harvest if navel
orangeworm is a problem. |
Bait ground
squirrels, if needed, when vegetation
begins to dry. |
Other
pests you may see:
- Phytophthora root and crown rot
- Crown gall
- Redhumped caterpillar
- Fall webworm
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| What should you be doing during this time? |
Harvest nuts promptly to reduce potential for navel
orangeworm damage and to preserve kernel
quality. |
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Sample nuts at harvest to evaluate your pest management
program.
Evaluate this season's
management program and plan for the next season's management. |
**Pesticide application checklist |
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When planning for possible pesticide applications in an
IPM program, review and complete this checklist to consider
practices that minimize environmental and efficacy problems.
- Choose a pesticide from the UC IPM Pest
Management Guidelines for the target pest considering:
- Select an alternative chemical or nonchemical
treatment when risk is high.
- Choose sprayers and
application procedures that keep pesticides on
target.
- Identify and take special
care to protect sensitive areas (for example, waterways
or riparian areas) surrounding your application
site.
- Review and follow label for pesticide handling,
storage, and disposal guidelines.
- Check and follow restricted entry
intervals (REI) and preharvest intervals (PHI).
- After an application is made, record application
date, product used, rate, and location of application.
Follow up to confirm that treatment was effective.
- Consider water
management practices that reduce pesticide movement off-site:
- Install an irrigation recirculation
or storage and reuse system.
- Use drip rather than sprinkler or flood
irrigation.
- Limit irrigation to amount required
using soil moisture monitoring and evapotranspiration
(ET).
- Consider vegetative
filter strips or
ditches.
- Redesign inlets into tailwater ditches
to reduce erosion.
- Consider management practices
that reduce air quality problems.
- When possible, choose pesticides that
are not in emulsifiable concentrate (EC) form which
release volatile organic compounds (VOCs). VOCs react
with sunlight to form ozone, a major air pollutant.
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