Bill Cissel, Extension Agent – Integrated Pest Management; bcissel@udel.edu
There have been numerous reports of small grain fields with armyworms this week. The threshold for armyworms is 1 per linear ft of row in barley and 1-2 per linear ft of row in wheat. Some fields may also have infestations of grass sawflies (wheat and barley: threshold 0.4/linear row ft). Keep in mind, not all insecticides labeled for armyworm control will provide grass sawfly control. With barley harvest right around the corner, also make sure you consider the days to harvest restrictions when making an insecticide application.
True Armyworm
Grass Sawfly
Here is a link to our Grass sawfly and True armyworm fact sheet for more info on sampling and decision making:
http://extension.udel.edu/factsheets/grass-sawfly-and-true-armyworm-management-in-small-grains/
Here is a link to our Small Grain Insecticide Recommendations:
https://cdn.extension.udel.edu/wp-content/uploads/2012/05/18063827/Insect-Control-in-Small-Grains-final-2017.pdf
Not sure how to identify true armyworms and grass sawflies? Here is a link to Guess the Pest Week #7 with information on identification:
http://extension.udel.edu/weeklycropupdate/?p=10378