There have been reports of armyworm activity in wheat fields in SW Ontario, which means it won’t be long before they make the move into vegetable crops.
Armyworm larvae are dull-green to brown with white-bordered stripes running laterally along the body. There is a dark, diagonal band at the top of each proleg. They are as large as 5 cm (2 in.) in length at maturity.
Scout vegetable crops regularly for larvae and signs of feeding. During the heat of the day, the larvae often hide in the whorl or in the soil beneath the plant. Sweet corn plants are most susceptible to armyworm feeding at the seedling to mid-whorl stages. On seedling corn, use a control threshold of 10% damaged plants. After the mid-whorl stage the threshold increases to 50% damaged plants.