Pecan phylloxeras
Description
Species include Phylloxera notabilis, P. russelae ("Leaf" Phylloxeras), and Phylloxera devastatrix ("Stem" Phylloxera).
The adults and nymphs are tiny, soft-bodied, cream colored insects resembling aphids. They are rarely seen.
Damage
Hard swellings or galls (Figure 7) appear on succulent leaf leaflets or growing terminals. Leaflets with 4 to 5 or more galls may drop. Severe infestations may produce partial defoliation of affected trees and may interfere with photosynthesis. Terminals infested by P. devastatrix have galls where the nut clusters would normally develop. This is the most damaging phylloxera.
Seasonal History
Phylloxera overwinter in the egg stage in protected places on branches. The young delicate aphid-like insects appear in spring - - about the time the buds unfold. The insect inserts its beak into new leaf or terminal growth and a gall forms that soon envelopes the insect. The insect matures within the gall and lays a large number of eggs. Young hatch from these eggs and develop into winged forms. Usually, in late May or early June the gall splits open and releases the insects. Infestations may start on one tree and spread out to others. There are several generations per year - - as long as there is new growth on the tree.
When to Control
Spray trees infested the previous year and surrounding trees during the delayed dormant period. Time sprays with bud breaks of the earliest varieties. A second application two weeks after the first may be required for heavy infestations.
