Sugarbeet Root Aphid

Sugarbeet root aphid, as the name implies, is restricted to the roots; generally, the aphid is associated with fibrous roots rather than the main storage root. Winged aphids may occasionally be seen in woolly wax masses in the crown as they crawl up from the roots to fly to new hosts. Wingless forms found on roots are yellowish in color and secrete a dull, white waxy substance, giving the root a mealy appearance.

This aphid is more commonly found in the Central Valley; it is not common in Imperial Valley.

Severely infested plants become chlorotic and wilt easily; under conditions of prolonged moisture stress, the storage root becomes flaccid and rubbery. Infestations in the field often appear as circular or elliptical patches in which the foliage on plants is wilted or, in extreme cases, collapsed and dying.

Thoroughly work infested fields immediately following harvest and destroy all ground keepers (beets left in the field following harvest). Destroy weed hosts, particularly lambsquarters and redroot pigweed, giving special attention to field margins, which may not come under the usual postharvest tillage program. Do not replant fields to a host crop (sugarbeets, table beets, spinach, chard) for a minimum of 3 years, and control potential weed hosts in all succeeding crops. Thoroughly clean all equipment and implements before moving from an infested to a noninfested field. Never use tailwater from an infested field to irrigate a field planted to a susceptible host because the aphid is readily transported in irrigation water. Finally, avoid water stress and keep the interval between irrigation cut-off and harvest to a minimum, as yield and quality losses are greatest in water-stressed sugarbeets.

Sugarbeet root aphid is attacked by the larvae of a predatory fly and is susceptible to a fungus disease. It is doubtful that either are capable of controlling aphid populations at this time, but the importance of these controls may increase in the future.

No economic thresholds have been established for sugarbeet root aphid. However, studies in California show that even light to moderate infestations (less than 10%) can cause serious yield reductions. If sugarbeet root aphid is found, implement the cultural and sanitary practices outlined above. No chemicals are currently registered for use on sugarbeet root aphid in California.