Pest description and crop damage Pinhead-sized, pale white-yellow aphid that colonizes taproot. They are covered with waxy white secretions that superficially resemble mold.
Scouting and thresholds No formal economic thresholds exist for root aphid insecticide treatment decisions. Root aphids typically infest fields during late summer, which makes "rescue" treatments using registered insecticides impossible.
Root aphids can be managed by planting approved resistant varieties. Maintaining a proper irrigation schedule can help plants to resist attack from root aphids; aphids are favored by drier soils and drought-stressed plants.
Root aphids are attacked by a predatory fly that generally keeps infestations in check. We do not yet know enough about arthropod natural enemies to suggest practical ways of manipulating and enhancing their effects other than avoiding any unnecessary insecticide applications.
- imidacloprid (Advise 2FL, Agrisolutions Nitro Shield, Agristar Macho 600 ST, Attendant 480 FS, Axcess Insecticide Seed Treatment, Dyna-Shield Imidacloprid 5, Gaucho 480 Flowable, Gaucho 600 Flowable, Senator 600FS, Sharda 5SC)-Application only by commercial seed treaters; no on-farm seed-treatment application.
- terbufos (Counter CR Lock'n Load, Counter 20G Lock'n Load, Counter 20G Smartbox, Counter 15G Lock'n Load, and Counter 15G Smartbox)-Apply postemergence at 0.6 to 1.2 oz ai/1,000 row feet. One application per year. Do not place in direct contact with seed. Apply in 5- to 7-inch band over the row and lightly incorporate. PHI 110 days.
- thiamethoxam (Actara, Cruiser 5FS)-Application only by commercial seed treaters; no on-farm seed-treatment application.