This year is turning out to be a terrible year for insect problems in the Klamath Basin. The mild winter and warm spring temperatures are perfect for supporting insect pest development. Over the last week I've observed cereal leaf beetle larvae and Russian wheat aphid in winter and spring wheat and barley fields. Most fields have low populations that do not warrant insecticide treatment, but insect populations appear to be building in a few fields. I ran the degree day model for Cereal Leaf Beetle using Tulelake weather data today. Peak egg hatch occurred on May 23rd 2015 and peak larvae emergence is predicted to be June 14th 2015. Almost all eggs from the overwintering generation should hatch by June 25th. Below are pictures of a Cereal Leaf Beetle adult, larvae, and feeding symptoms.
The following link discusses Cereal Leaf Beetle monitoring and control from the Pacific Northwest Insect Management Handbook http://insect.pnwhandbooks.org/agronomic/small-grain/small-grain-cereal-leaf-beetle
CDFA and IREC are cooperating to rear the biological control agent T. Julis this year. Hopefully we will be able to collect enough parasitized Cereal Leaf Beetle to release in Tulelake grower fields this year. If you find parasitized larvae in your fields please notify UC IREC staff so we can obtain a better understanding of the presence of T. Julis in the Tulelake Basin. Contact the Siskiyou County or Modoc County Department of Agriculture for information on transporting hay and grain if you suspect live cereal leaf beetle may be present in the commodity. Also make sure to clean equipment after driving in infested fields.
Russian wheat aphid has been found in a few fields in low numbers. Russian wheat aphid injects a toxin in the plant. This toxin is responsible for the characteristic white longitudinal streaks on leaves shown in picture below. Infested leaves often curl up like a soda straw; curled flag leaf can cause grain heads to be distorted. The following two links describe small grain aphid identification, monitoring, and control. UC-IPM Guidelines for Russian Wheat Aphid http://www.ipm.ucdavis.edu/PMG/r730300211.html Small Grain Aphids- Pacific Northwest Insect Management Handbook http://insect.pnwhandbooks.org/agronomic/small-grain/small-grain-aphid
