How to Manage Pests
UC Pest Management Guidelines
In California, this aphid is prevalent in the San Joaquin Valley. Winged and wingless adults of the black peach aphid are shiny black and about 0.1 inch long. The nymphs are reddish brown. Wingless forms overwinter on the roots of nectarine and other closely related trees. In early spring, some migrate from roots to new growth and start colonies on the young leaves. Several generations of female aphids are produced. In early summer, winged adults are produced and migration to other trees occurs. Aboveground colonies usually disappear by midsummer as wingless forms migrate to the roots to feed and overwinter.
Injury consists of leaf curling, yellowing, and premature drop; the leaf curling is first evident at shoot terminals. If aphids are abundant, honeydew excretion may cause black sooty mold to appear on leaves and fruit. Ants may also become a problem, because they tend the aphids while they are on the roots.
In spring when growth begins, look for colonies of this aphid when monitoring other pests. The multicolored Asian lady beetle, Harmonia axyridis, is a common predator of these aphids. This aphid is not particularly damaging, and populations may be managed by predators. If this aphid has presented problems in the past, take control measures in spring.
UC IPM Pest Management Guidelines: Nectarine