Pea Weevil Reference Page
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Pea Weevil Reference Page
Peas, Green and Dry—Pea weevil
Pest description and crop
damage The adult pea weevil is a chunky beetle about 0.1875 inch long
with a short, broad snout. It is brown flecked with white, black, and gray
patches. The top of the abdomen is exposed behind the wing covers. The larva
is C-shaped, up to 0.25 inch long, legless, brown-headed, and cream-colored.
Adults feed on pea pollen, and
the female lays eggs on developing pea pods. The larva burrows directly through
the pod, where it feeds and develops in the developing pea seed. While one
larva develops in a single seed, nearly every pea may be infested when populations
are high.
Biology and life history
The adults overwinter with the peas primarily in storage, but also in the
field. The pea weevil emerges about the time the peas are blooming, feeding
on flowers (pollen and petal), leaves, or pods. The elongated yellow eggs
are laid on the outside of the pods singly or in pairs. Although one to a
dozen eggs are laid per pod, only one larva develops per pea. Hatching occurs
in 1 to 3 weeks. The larva burrows through into the pea and matures in 5
to 6 weeks. Infested peas "heat," aiding in the development of the larva.
Pupation takes about 2 weeks, late in the summer. Adults may leave the pea
immediately or stay inside the pea all winter. There is only one generation
per year.
Scouting and thresholds
One weevil in 25 sweeps may result in 10% infested peas at harvest. Take
samples along field margins, fence rows, and in the field. Pods also can
be examined for eggs.
Management—cultural control
It is very important to destroy
crop residues. Do not plant infested seed unless it is fumigated. Careful
harvesting prevents shattering that can disperse weevils throughout fields.
Volunteer plants should be destroyed. Early planting and harvesting is also
desirable.
Management—chemical control
Insecticides must be applied
soon after first blooms appear and before pods start to form. Additional
applications may be needed to control migrating weevils.
1. bifenthrin (Capture 2EC) at
0.033 to 0.1 lb ai/a. PHI 3 days. Succulent only. Do not apply more than
0.2 lb ai/a per season. Restricted use. Toxic to fish.
2. carbaryl (Sevin); refer to
label for rates. PHI 3 days for succulent, 14 days for grazing, 21 days for
dried peas, seed, hay. Observe plant response precautions. Latex-based formulations
of carbaryl, such as Sevin XLR Plus, are least hazardous to bees.
3. endosulfan (Endosulfan 3EC)
at 1.3 to 2.6 pints/a. PHI zero days. Succulent peas only. Use only on peas
to be harvested by combine. Do not feed treated vines to livestock or allow
livestock to graze in treated fields.
4. endosulfan (Endosulfan 50WS,
3 EC); refer to label for rates. PHI 1 day. Pea seed crop only. Use only
on peas harvested by combine. Do not feed treated vines or threshing.
5. esfenvalerate (Asana XL) at
0.03 to 0.05 lb ai/a. PHI 21 days. Do not exceed 0.2 lb ai/a per season.
Do not feed or graze treated vines. ID, OR, and WA only.
6. malathion (Malathion 8) at
1 to 2.5 pints/a. PHI 3 days. Do not feed or graze treated vines.
7. malathion (Malathion ULV)
at 8 oz/a. PHI 14 days.
8. malathion + methoxychlor at
2 to 2.5 quarts/a. PHI 7 days.
9. methoxychlor. Refer to label
for rates. PHI 7 days.
10. methyl parathion (Penncap-M)
at 2 pints/a. Austrian winter pea, dry. PHI 10 days, 15 days for forage.
Warning:Never spray microencapsulated methyl parathion on blooming
weeds in pea fields or adjacent fields. If misused, this formulation is especially
hazardous to honey bees and other pollinating insects because of its strong
tendency to contaminate pollen. To protect pollinators, use before May 15.
OR only.
11. phosmet (Imidan 70W) at 1 to 1.33
lb product/a. PHI 7 days. Do not cut treated fresh pea forage for hay
within 10 days of application. Refer to label for grazing/feed restrictions.
Warning: Imidan residues can remain highly hazardous to bees for up
to 4 days. Do not use this material if blooming weeds are present in
the field edges or adjacent areas. WA only.
Dry edible and seed pea—Pea weevil
Pest description and crop damage
A small, grayish-brown weevil 0.2 inch long, marked with dark and light spots.
Larvae feed within the seed and destroy its viability.
Sampling and thresholds
Usually, one weevil per 25 sweeps of an insect net will result in 10%
weevily peas at harvest.
Management—chemical control
Apply insecticides to kill adults
before they lay eggs. Once eggs are on pods, it is too late to prevent weevily
seeds. Therefore, apply insecticide when first pods appear and before eggs
are laid.
1. methoxychlor at 1.5 to 3 lb
ai/a. PHI 7 days.
2. malathion at 1.25 lb ai/a.
PHI 3 days.
3. Imidan at 0.75 to 1 lb ai/a.
PHI 7 days. Do not feed forage to livestock within 7 days of application.
Do not cut fresh pea forage for hay within 10 days.
4. Asana XL at 0.03 to 0.05 lb
ai/a. PHI 21 days. Do not exceed 0.2 lb ai/a per season. Do not feed or graze
treated vines.
NotesProtect pollinating
insects. See "How to Reduce Bee Poisoning from Pesticides" in this book.
Source: 2003 PNW Insect Control Handbook
Integrated Pest Management Information:
May 7, 2003-jn