Chard, Swiss-Leafminer

Includes

Pea leafminer (Liriomyza huidobrensis)
Vegetable leafminer (L. sativae)

Pest description and crop damage Adults are small black to gray flies with yellow markings. The body is covered with long, stiff bristles. Larvae are a nearly translucent white or yellow and about 0.25 inch long when mature. Eggs are white, cylindrical, and laid singly or in small groups. Both larvae and adults damage plants. Larval feeding results in slender, winding trails on the leaves, which form large, white blotches when mining becomes severe. Adults can make as many as 100 feeding punctures on a single leaf. Around 5% of these punctures may contain actively feeding larvae. Excessive mining renders leaves unmarketable, reduces photosynthetic capacity, and provides easy access for disease organisms.

Pest monitoring Regularly check young seedlings and plants for leaf mines. Most mines occur on cotyledons and the first true leaves. Some mines are more visible when seen from the underside of the leaf.

Management-biological control

Natural enemies, especially parasitic wasps, commonly reduce populations of leafminers, unless they are killed off by insecticides applied to control other pests. To avoid killing beneficials, choose selective pesticides for treating other pests, whenever possible. Other parasites attack leafminers, but because leafminers feed within the leaf, they generally are protected from predators.

Management-cultural control

Row covers work well in excluding egg-laying female flies.

Home gardeners: remove and destroy affected leaves.

Management-chemical control: HOME USE

  • acetamiprid
  • azadirachtin (neem oil)-Some formulations are OMRI-listed for organic use.
  • carbaryl
  • cyfluthrin
  • malathion
  • permethrin
  • plant-derived essential oils (rosemary, peppermint etc.)-Some formulations are OMRI-listed for organic use.
  • pyrethrins-Some formulations are OMRI-listed for organic use.
  • spinosad-Some formulations are OMRI-listed for organic use.
  • zeta-cypermethrin

Management-chemical control: COMMERCIAL USE

  • abamectin (Agri-Mek, Epi-Mek) at 0.009 to 0.019 lb ai/a. PHI 7 days. REI 12 hr. Retreatment interval 7 days. Do not exceed 0.056 lb ai/a per season. An organosilicone surfactant will increase translaminar uptake and transport.
  • Chenopodium ambrosioides extract (Requiem) at 2 to 3 quarts formulated product per acre. PHI 0 days. REI 4 hr. OMRI-listed for organic use.
  • chlorantraniliprole (Coragen) at 0.065 to 0.098 lb ai/a as soil, chemigation or foliar treatment. PHI 1 day. REI 4 hr. Do not exceed 0.2 lb ai/a per crop or 0.8 lb ai/a per season. Controls larvae.
  • clothianidin (Belay) at 0.15 to 0.2 lb ai/a soil treatment. Suppression. PHI 21 days. REI 12 hr. Do not exceed 0.2 lb ai/a per season.
  • cyantraniliprole (Exirel) at 0.088 to 0.133 lb ai/a. PHI 1 day. REI 12 hr. Retreatment interval 5 days. Do not exceed 0.4 lb ai/a per year.
  • cyromazine (Trigard) at 0.042 lb ai/a. PHI 7 days. REI 12 hr. Retreatment interval 7 days. Do not exceed five applications per crop.
  • dimethoate (Dimethoate 4E) at 0.25 lb ai/a. PHI 14 days. REI 48 hr. Do not exceed 0.5 lb ai/a per season. Retreatment interval 7 days.
  • dinotefuran (Scorpion 35SL) at 0.05 to 0.13 lb ai/a (foliar) or 0.23 to 0.27 lb ai/a (soil) treatment. PHI 7 days foliar or 21 days soil. REI 12 hr. Retreatment interval 7 days. Do not exceed 0.266 lb ai/a foliar or 0.532 lb ai/a soil application per season.
  • emamectin (Proclaim 5SG) at 0.01 to 0.015 lb ai/a (suppression only). PHI 7 days. REI 12 hr. Retreatment interval 7 days. Do not exceed 0.09 lb ai/a per season.
  • naled (Dibrom 8E) at 0.94 lb ai/a. PHI 1 day. REI 48 hr. Do not exceed 6.6 lb/a per season. Retreatment interval 7 days. Do not apply when temperature is over 90°F. Limit 7 treatments.
  • permethrin (Ambush 25WP, Pounce 25WP) at 0.1 to 0.2 lb ai/a. PHI 1 day. REI 12 hr. Do not graze or feed. Do not exceed 1 lb ai/a per season. Retreatment interval 7 days.
  • spinetoram (Radiant SC) at 0.0469 to 0.0781 lb ai/a. PHI 1 day. REI 4 hr. Retreatment interval 4 days. Do not exceed six applications or 0.266 lb ai/a per season. Follow resistance management procedures on the label. Do not apply to seedling leafy vegetables grown for transplant within a greenhouse, shade house, or field plot.
  • spinosad (Success, Entrust SC) at 0.09 to 0.16 lb ai/a. PHI 1 day. REI 4 hr. Do not exceed six applications or 0.45 lb ai/a per crop. A surfactant improves control. Entrust SC is OMRI-listed for organic use.
  • thiamethoxam (Platinum) at 0.078 to 0.172 lb ai/a. Soil applied. PHI 30 days. REI 12 hr. Do not exceed 0.172 lb ai/a per season. Suppression.