Insect problems of sunflowers
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Many insect pests belonging to several different groups attack cultivated sunflowers in North America. Sunflowers are native to this continent and weeds belonging to the same or closely related species are abundant throughout areas where cultivated sunflowers are grown. Thus, most sunflower insects are native and have been multiplying rapidly during the recent expansion in sunflower production. Discussion of the insect pests of sunflowers is facilitated by grouping them according to the part of the sunflower plant attacked, e.g., (a) leaf feeders, (b) stem and root feeders, and (c) head feeders. Leaf feeders are usually the easiest group to control. They are exposed to view, they and their damage are easily evaluated, and effective insecticidal controls can be applied when necessary. The stem and root feeders such as the carrot beetle in the South and cutworms in the North can cause severe damage before control measures are applied. However, many other species of stem feeders can be present in large numbers without causing economic damage. Head feeders include the sunflower moth, the banded sunflower moths, the sunflower seed maggot, the seed midge, and the seed weevil. These pests are potentially very damaging and, once they have entered the head, are difficult to control with insecticides. Traps baited with a synthetic pheromone are now available to monitor the abundance of sunflower moths. Further research on early warning systems to detect the abundance and distribution of other pests in this group is especially important. These will enable growers to apply controls before the pests are protected within the heads and will reduce the application of insecticides when they are not required.