Root Aphid

Order: Hemiptera
Family: Aphididae
Species: Pemphigus populivenae

Pests as nymphs and adults

Appearance

• Globular soft bodies (tear-drop, pear-shaped)
• Paired cornicles (backward pointing abdominal tubes)
• Piercing/sucking mouthparts on nymphs and adults

Symptoms

Above Ground

• Leaf yellowing and wilting (first along the edges)
• Small circular patches of collapsed plants - especially during moisture stress

Below Ground

• Patchy white waxy material "white mold" on roots and soil
• Short, limp, rubbery taproot with many root hairs

Biology

• Winter: overwinter as eggs within bark crevices on Populus species (Cottonwood and Poplar trees).
• Spring: "Stem mother" hatches from eggs as a dark-bodied, wingless female and feeds on emerging leaf gall that encloses the aphid. Over the next 1-2 months, the female produces 75-150 "spring migrant" females asexually, that have wings as adults and escape from the gall through a hole.
• Summer: Spring migrants have colonizing flights to sugar beet roots (may be directed or accidental). Infestations are the worst when soil is dry and cracked. There are multiple asexual generations on sugar beet roots. At this stage, aphids are 2-3 mm long, pale yellowish-white and dusted with white powder. Aphids are wingless and entirely female. In late summer, some winged aphids are produced and have massive return flights to poplar and cottonwood.
• Fall: After returning to wintering site, the migrant aphids give live, asexual birth to sexual males and females. These aphids are near-microscopic, mouthless (non-feeding) and wingless, solely for the purpose of mating and oviposition. Females lay a single white egg in the bark crevice. Aphids that remained at the beet fields continue to produce asexual wingless generations. They overwinter in the beet field soil or on weeds in ditches to colonize the sugar beets next spring.

Control Strategy

• Minimize initial colonization and establishment
• Slow rate of increase once established

Control Measures

Cultural

• Field rotation
• Maintain rapid vigorous plant growth
• Early-planting and fertility
• Avoid water stress
• Control weedy hosts, such as lambsquarter and pigweed, especially in field borders
• Clean tillage equipment between infested & noninfested fields
• Postharvest fall tillage
• Expose and kill overwintering aphids
• Eliminate alternate winter hosts (cottonwood and poplar)

Biocontrol

• Conserve natural enemies (predatory fly and fungus disease in soil) by minimizing soil insecticides

Pesticides

• No formal field monitoring methods
• Check the Database of Pesticides Registered in Idaho (Kelly Database) for pesticides registered in Idaho