Wheat Entomology Newsletter – June 1, 2021

Darren Cockrell: Darren.Cockrell@colostate.edu


Dr. Punya Nachappa: Punya.Nachappa@colostate.edu


Wheat Stem Sawfly – Adult Emergence

Wheat stem sawfly adults began emerging in the NE part of the state last week, with the first adults found on May 19th near Orchard, CO. When compared to previous years, the current adult emergence is following the expected pattern (Figure 1). Generally, the peak flight occurs approximately 2 weeks after the flight begins and lasts around 4-5 weeks in total. Lodging caused by wheat stem sawfly infestations starts as the wheat dries down, at an estimated 40% grain moisture. Video of sawfly flight can be viewed at: https://imgur.com/a/KWHcqzj

Wheat Stem Sawfly – Resistance Screening

As part of a multi-year study, researchers at CSU have been screening wheat relatives for novel wheat stem sawfly resistance traits. Greenhouse grown wheat relatives are brought to the field during wheat stem sawfly flight to allow for a natural infestation to occur (Figure 2A and B). The results from this experiment will give the wheat breeding program further direction as to what resistance traits may be deployed in future varieties. This work is being done in collaboration with the Wheat Genetic Resource Center at Kansas State University. Further results will be available in the wheat field days report.

Russian Wheat Aphid

Russian wheat aphids are continuing to be found in both high and low numbers (Figure 3). Across the state and many producers are applying insecticides. The timing of these applications aligns with that for rust fungicides, and many formulations allow for tank mixing. The benefit of treatment markedly decreases as the wheat head emerges and the flag leaf extends. Be sure to read and follow all label instructions. Information on management practices can be found at: https://wiki.bugwood.org/HPIPM:Russian_Wheat_Aphid


Brown Wheat Mite

Reports of damaging brown wheat mite populations have been dwindling, likely due to the heavy spring rain events over the past few weeks. A high density population of mites was still found at ARDEC in Larimer County.

Wheat Diseases

For wheat disease updates by Dr. Robyn Roberts, please see: Colorado Wheat Disease Newsletter – May 24, 2021 | Colorado Wheat


We would like to acknowledge the tireless work of the CSU researchers and extension agents for reporting pest problems throughout the state, including Erika Pierce, Ron Meyer, Barry Ogg, Wilma Trujilo, Kevin Larson, Brett Pettinger, and Laura Newhard, as well Dr. Frank Peairs for continuing to provide insight on pest problems during his retirement.

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