County Agent News
July 18, 2022
Bertha Armyworm and Diamondback Moth in Canola
It’s time to start scouting canola fields for Bertha Amyworms and Diamondback Moth Larvae.
Bertha armyworm: Larvae are about 1½ inches long and vary from green and brown to velvet black when mature. Check several locations per field. At each location, mark an area of 0.25 square meter (50 cm by 50 cm) and shake the plants to dislodge any larvae that may be on the plants. Count the number of larvae on the ground. Carefully inspect under clumps of soil and leaf litter, where larvae hide during the day. Counts are multiplied by four to determine the average number of larvae per square meter for each field. For more information see the NDSU Extension Publication Bertha armyworm in Canola E1347
Diamondback moth: The newly hatched larva is light green and turns a darker green as it matures and is about ½ inch long. Scout for larvae in the field by pulling all plants from a 1-square-foot area. Beat collected plants onto a clean surface or into a white bucket and then count the number of larvae dislodged from plants. Larvae often will dangle from canola plants on a silk thread. Repeat this procedure in at least five locations in the field to obtain an average of the number of larvae per square foot. For more information see the NDSU Extension Publication Diamondback moth in Canola E1346.
FUSARIUM HEAD BLIGHT (SCAB) RISK
This past weekend’s weather for most of the state presented conditions of high humidity, rain, and prolonged dews. These three factors greatly contribute to scab risk and now an elevated scab risk exists for small grains. According to the NDSU Small Grain Disease Forecasting Model, the greatest scab risk exists for spring wheat varieties that are rated as very susceptible or susceptible to Fusarium head blight. This includes hard red spring wheat and durum varieties rated 6 or higher, however there is still moderate risk in some areas for the spring wheat varieties that are rated as moderately susceptible and moderately resistant varieties (rated 5 or less).