Temperatures are on the rise and so is aphid activity! There have been reports of aphids popping up all over Texas recently, so if you haven’t already, make sure to get out and scout fields for three common species:
Bird cherry-oat aphid, Rhopalosipum padi
Greenbug, Schizaphis graminum
Russian wheat aphid, Diuraphis noxia
Mark Brown (Lubbock Co Ag Agent) and I stopped in a wheat field the other day in Lorenzo, TX. Mark noticed purple, longitudinal streaks down the leaf steam and wrapped up inside was a colony of Russian wheat aphids (see photo below). Russian wheat aphids, RWA, feed in the whorl of new plant shoots and the plant curls around the aphids, protecting them from damage. The saliva of Russian wheat aphids is toxic to plants and this is what causes the discoloration.
|Russian wheat aphids on winter wheat in Lorenzo, TX.|
Greenbugs are similar in color to the Russian wheat aphid, but have a characteristic green stripe down their back and longer antennae and cornicles than the RWA. Damage by greenbugs appears as brown or orange leaves that appear to be ‘scorched.’ As the infestation increases and spreads out, discolored patches are visible in the wheat.
Bird cherry-oat aphids are smaller, olive green colored aphids with pink coloration on the underside. Their numbers have been on the rise down in Hill County, according to Xandra Morris (IPM Agent). Check out her blog on BCOA for scouting tips and thresholds!
The good news is that beneficials are out and have the ability to suppress RWA populations. I’ve seen green lacewing eggs on wheat as well as pink-spotted ladybeetles (Coleomegilla maculata). When inspecting your fields, take into account the predators and parasitoids that will provide natural control when making the decision to treat. Use this Cereal Aphid Decision Tool by Oklahoma State University to help with aphid management. Dr. Ed Bynum (Extension Entomologist– Amarillo) has information on economic thresholds for RWA developed by Texas A&M Agrilife Extension.