When monitoring for adults, whole plant counts are used most commonly; however, sticky traps can be used as well. Whole plants count focus on the ear of the corn plant, while still accounting for the whole plant. It is a count of the total number of adult corn rootworms on the plant. Adults like to aggregate at the ear and feed on the silk, especially when the silks are fresh. While walking up to the corn plant, count any corn rootworms that fly away and gently grab the silk of the ear to trap any adults. Quickly scan the rest of the plant, counting any other adult corn rootworms. After scanning the plant, check the ear of the corn. It is important to look closely in the silk since they will often be inside the ear feeding on the silks, including any that were trapped initially by hand when the ear was grabbed.
Sticky traps are placed at about ear height. They are often yellow to attract the adults. The adult corn rootworms will stick to the trap when they land on it. This allows for accurate estimates of adult populations in a field. Though they can be used in cornfields, sticky traps are most often used when monitoring corn rootworms in soybean fields, especially in areas where rotation resistant corn rootworms are present. Rotation resistant corn rootworms will be discussed later in this module. |
