The lygus bug or "tarnished plant bug" has the potential of being a serious insect pest in field pea. Lygus bugs adults are slightly less than ¼ in. in length and about half as wide. Body color ranges from pale green to light brown but there is a distinct lighter colored triangular shaped marking, located near the center of its back where the wings join. Adults survive the winter protected in ground litter, crop residues and buildings. They may become a nuisance in households during warm winter days.
Adults lay eggs in the spring and feed on various plants. Eggs hatch into nymphs in about 10 days and reach maturity in a month. Nymphs are brighter green in color, smaller than adults, have wing pads that become more pronounced in later nymphal stages. Smaller first and second instar nymphs somewhat resemble pea aphids, however, they are much more active than pea aphids. Later instars have distinct black markings on the abdominal segments.
Lygus bugs feed preferentially on meristematic tissue or developing reproductive tissue resulting in shriveled seed. "Chalk spot" is the appearance of a chalky white spot which may appear on the dried seed and has been documented in lentils. It is considered as damage mainly because it severely affects the appearance of the seed, lowering the grade and marketability. In 1996 and 2002, chalk spot was a concern in the North Dakota pea crop. Chalk spot damage to some pea samples was as high as 27 percent; however, it could not be documented in all samples that it was the lygus bug that caused the damage. The other probable cause was that the pea was harvested at too high moisture. Peas harvested at high moisture are susceptible to bruising as they are harvested or handled roughly, causing damage similar to chalk spot.
Lygus bugs may move from nearby alfalfa or canola fields, especially after alfalfa hay is cut. In this situation monitoring is important, focusing on the field edge near the source of migrating lygus. When peas are in bloom and pods have begun to form, sweep nets can be used to detect lygus presence.
In Idaho the threshold for lygus bugs in field peas is 7 – 10 lygus per 25 sweeps (U.I. Bulletin No. 664).
Product List for Lygus Bug:
Insecticide |
Lbs Active Ingredient per Acre (Fl oz. or oz. product) |
Preharvest Interval, remarks |
|
Carbaryl 4L, 80S, XLR1,2 |
1 – 1.5 qt (4L) 1 ¼ - 1 7/8 lbs (80S) 1 – 1.5 qts (XLR) |
PHI 14 days grazing or harvest for forage, 21 days harvest dry seed. Do not apply more than 6 qts (4L or XLR) or 7.5 lbs (80S)/A/ season. |
|
Dimethoate (several formulations) 1,2 |
½ - 1 pt (400) ¾ - 1.5 pt (267) ½ - 1 pt (4E) |
PHI 0 days. Do not feed treated vines. Do not make more than 1 application per season. Highly toxic to bees. |
|
Fury 1.5R |
3 – 4.3 oz |
PHI 21 days. 12 hr REI. Do not apply more than 24 oz per season. |
|
LannateR,2 |
0.5 -1 lb (SP) 3pts (LV) |
PHI 14 days to harvest, graze or hay. Do not apply more than 4.5 lbs ai /season. Do not make more than 10 applications per crop. Highly toxic to bees, do not apply when bees are foraging. |
|
Mustang 1.5ECR |
2.72 – 4 oz |
PHI 21 days. 12 hr REI. Do not apply more than 24 oz per season. |
|
Methyl parathion 4ER |
1-3 pt |
15 days for 1 pt/A or less. 21 days for more than 1 pt. Do not apply if crop or weeds are in bloom. |
|
R Restricted Use Pesticide 1 Labeled for chemigation 2Several formulations. |
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The information herein is supplied with the understanding that no discrimination is intended and that listing of commercial products, necessary to this guide, implies no endorsement by the authors or the Extension Services of Nebraska, Colorado, Wyoming or Montana. Criticism of products or equipment not listed is neither implied nor intended. Due to constantly changing labels, laws and regulation, the Extension Services can assume no liability for the suggested use of chemicals contained herein. Pesticides must be applied legally complying with all label directions and precautions on the pesticide container and any supplemental labeling and rules of state and federal pesticide regulatory agencies. State rules and regulations and special pesticide use allowances may vary from state to state: contact your State Department of Agriculture for the rules, regulations and allowances applicable in your state and locality. |
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Categories: Dry Peas, Insects, Lygus Bugs
Date: 04/29/2006