Michael J. Hall, Bollich, Patricia A. | 8/2/2006 1:07:46 AM
The yellow spots are the result of feeding on the leaves by black pecan aphids. The spots, generally rectangular to multi-angular in shape, will eventually turn brown. High numbers of black pecan aphids can cause severe defoliation during the late summer and early fall.
The use of an insecticide is the primary method used by growers to control the black pecan aphid. Because of their potential for causing severe defoliation and their rapid rate of reproduction, the treatment threshold for black pecan aphids is one aphid per compound leaf. It is very important that trees are inspected on a regular basis, particularly during the summer months and into the fall, as this is when populations of the black pecan aphid can quickly reach damaging levels.
More detailed information on the distribution, description, life cycle, damage, and control of the black pecan aphid can be found on the Black Pecan Aphid fact sheet on the Entomology page of the Pecan Station website.
Question answered by Dr. Mike Hall, Pecan Research-Extension Station entomologist.
The LSU AgCenter and the LSU College of Agriculture