I received a note yesterday about aphids appearing in winter wheat fields in the southern Wheat Growers territory. I also saw a report from SDSU about the subject. With the warm fall conditions creating fairly lush top growth on winter wheat stands, it is imperative that you go take a good look at those fields. The primary aphid being found is the bird cherry-oat aphid, with a dark green color and brownish band on the abdomen. This aphid is of concern because it can vector the Barley Yellow Dwarf Virus (BYDV). There are also some reports of greenbug on winter wheat- a smaller, all bright green aphid with long antennae. Look carefully at plants, looking near the base of the plants for the aphids. Light frost will not kill the aphids, as they can hide toward the base of the plant.

We may need to consider treating aphid populations, if the numbers are very high. I do not want to see a great winter wheat stand lose out to BYDV, and there is nothing we can do to stop the infection once it takes place. University recommendations are to treat with insecticides if there are on average 20 bird cherry-oat aphids per plant or 15 to 25 aphids per linear foot of row in the fall. For greenbug, thresholds are higher - 25 to 50 aphids per linear foot of row. My thought is to err off the LOW end of these ranges and treat as needed- protect what we have! We still have decent conditions for at least another couple weeks, so aphid populations could continue to be active for a while.

Insecticide choices are wide open. Aphids are not particularly hard to wipe out, but check coverage in really heavy plant stands.