Yesterday, I checked a variety trial near Alliston that was planted late, on May 27. There was a moderate to high population of small black cutworms in the plots of late varieties, those that still had green foliage. Although the worms were small, there were also tubers with feeding damage. Small larvae of the black cutworm feed on the foliage in the evenings and remain buried in the soil near the plants during the day. Large black cutworms usually feed on tubers and do not come up to the soil surface.
Scout late-planted fields for black cutworm feeding damage, especially in Dufferin county. If around 10 per cent of the plants have holes on the leaves (see photo) an evening spray is recommended. The insecticides Voliam XPress and Coragen are registered to control this pest. Lorsban also controls black cutworm. It can be applied as long as the crop is not going to be marketed in the United States.
The weather changes everything — I never expected to be sending a black-cutworm alert in September!
