Wheat Entomology Newsletter – June 17, 2021

Darren Cockrell: Darren.Cockrell@colostate.edu

630-649-4419

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

785-383-4873

Wheat Field Days

We had a great time touring the Wheat variety trials, meeting wheat growers and other stakeholders! We hear your concerns about the wheat stem sawfly and are committed to reducing the impact of this pest along with Colorado wheat breeding program. We learned a lot from these trips including to pack a hat, a jacket for the windy days and more sunscreen! Thanks to everybody that made the Wheat field days a great success! See you all next year!

Wheat Stem Sawfly – Adult Flight

The wheat stem sawfly adult flight is past its peak and will likely last 1-2 more weeks (Figure 1). Expect to see lodging in infested wheat fields as the wheat dries down, beginning at approximately 40% grain moisture. Lodging is generally pronounced on field edges. We will continue monitoring for parasitoid abundance after the wheat stem sawfly flight has ended.

Wheat Stem Sawfly – Solid Stem Breeding

As part of an ongoing collaboration with CSU’s wheat breeding program, new wheat varieties in breeding plots are being assessed for stem solidness as an effort to combat wheat stem sawfly (Figure 2). Stem solidness has been shown to slow larval development and can keep wheat stems from lodging due to sawfly feeding. Fortify SF, a semi-solid variety, is the most notable variety to come from this collaborative effort (https://plainsgold.com/wp-content/uploads/2020/04/fortify-002.pdf).

Wheat Stem Maggot

Wheat stem maggot is generally not considered a pest of economic importance in Colorado, however the larvae are often mistaken as wheat stem sawfly as they are both stem boring insects (Figure 3A-B). The telltale sign of wheat stem maggot damage is the head of wheat turning white, while the stem and leaves remain green (Figure 4).

Wheat Diseases

For wheat disease updates by Dr. Robyn Roberts, please see: https://coloradowheat.org/2021/06/colorado-wheat-disease-newsletter-3/

Acknowledgements

We would like to acknowledge the tireless work of the CSU researchers and extension agents for their work on this report including Erika Peirce, Laura Newhard, and Dr. Esten Mason, as well Dr. Frank Peairs for continuing to provide insight on pest problems during his retirement

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