Insect Pests for Sunflowers

Types

Wireworms are the larvae of click beetles and a common sunflower pest as they feed on a variety of flowers and live in the soil near infested plants. Wireworms are slender larvae that measure 1.5 to 2 inches in length and are yellow, white or copper colored. Another common pest of sunflowers is the sunflower root weevil, a black beetle measuring 1/4 inch in length with a short snout. Sunflower root weevil larvae are white, legless and 1/4 inches in length. Both the adult weevil and the larvae feed on sunflowers.

Wireworms damage sunflowers by feeding on young seedlings, germinating seeds or plant roots. Infestations of this pest is most common in areas that grain crops have been grown previously. Sunflowers suffering from wireworm infestations often wilt and die. The sunflower root weevil larvae feeds primarily on sunflower roots, under the soil surface. Heavy infestations can cause affected plants to wilt and die. The adult sunflower root weevil feeds on the leaves of the sunflower, causing foliage to appear chewed or have holes in them. Feeding from the sunflower root weevil can cause head drop to occur.

Wireworm infestations must be prevented before planting. Insecticides are the recommended means of controlling wireworms and must be applied prior to planting sunflowers. There are currently no recommended means of prevention for sunflower root weevils.

Home gardeners may wish to sample the soil before treating it for wireworms prior to sunflower planting. Traps are available at your local garden center that help determine if you need insecticides before planting. Digging up a sample of the soil and examining it for wireworms is another way to determine if they are present. The presence of 12 or more wireworms in soil indicates the need for insecticides. Soil drenches and seed treatments are available for the prevention of wireworms, but must be applied before planting the sunflowers. There are currently no recommended chemical control methods for the sunflower root weevil. In most areas, damage from this pest is minimal and control is not needed.