Onions XXV-3
Vegetable Leafminer
Whitney S. Cranshaw
Leafminer
Identification (and life cycle/seasonal history)
Adults are tiny yellow and black flies. Females lay eggs underneath the leaf surface. Larvae develop by feeding underneath the leaf epidermis, creating a serpentine leaf mine that gradually increases in width as the larvae grow. Pupation occurs within the mines and adults emerge.
Vegetable leafminer has a very wide host range and can produce similar mines on many other vegetable crops including beans, tomatoes, cabbage, and squash.
Plant Response to Damage
Larvae of vegetable leafminer create meandering mines underneath the surface of leaves. Except during extraordinary infestations this damage is insignificant to onion yield. However, damage is very conspicuous and produces unacceptable blemishing of green onion.
Management Approaches
Natural Controls
Vegetable leafminer has several natural enemies, particularly parasitic wasps. These will normally suppress vegetable leafminer to non-damaging levels. Outbreaks of vegetable leafminer are almost always associated with insecticide use that destroys natural enemies.
Sampling
Adults can be collected on yellow sticky traps.
Regularly surveying fields can readily detect changes in leaf mining. However, parasites often kill leafminers after some mining has occurred so plants should be carefully examined to determine if leafminers are being killed by these natural enemies.
Chemical Control
Outbreaks of leafminers in green onions have occurred following repeated use of Guthion/azinphosmethyl and Lannate. Limiting early season treatments of insecticides will usually allow adequate natural control of leafminers. Mustang/Fury applications can control leafminers, but should not be applied excessively.
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Product List for Vegetable Leafminer: |
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Insecticide |
Product per acre |
Preharvest Interval, Remarks |
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Mustang, Fury |
0.035-0.05 lb (3.0-4.3 fl. oz.) |
(7 days PHI, 12 hr reentry) Pyrethroid (zeta-cypermethrin) insecticide. Maximum 0.3 lbs ai/acre per season. |
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RRestricted use pesticide. 1Labeled for chemigation. |
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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 regulations, 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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