According to the Kansas State University Extension, numerous pests afflict sunflowers, although they point out that, in commercial operations, they are rarely significant. Furthermore, certain sunflower pests increase the likelihood of subsequent fungal infections that further damage the plant. Organic pest control methods use chemical-free strategies that often mimic natural defenses.
The Kansas State University Extension lists several insect pests that can damage sunflowers. Cutworms, as the name suggests, cut into seedlings at the base, killing the plant. Sunflower moths, sunflower beetles, grasshoppers and caterpillars damage or defoliate leaves. Seed weevils feed on seeds, while stem weevils lay their eggs inside plant stems, weakening the plant. Sunflowers are also prone to bird and animal pests.
Planting dates offer some control of common sunflower pests. According to the Texas Agricultural Extension Service, waiting until mid-June or later to plant eliminates harm from stem weevils. Later plantings also help to control sunflower beetles and sunflower moths, the latter of which is the most damaging pest to sunflowers. However, as the Kansas State University Extension points out, early planting is not a cure-all, as it increases susceptibility to seed loss from seed weevils and birds, a concern if you are growing flowers for seed.
Good cultural practices tend to limit pest problems, and the pests associated with sunflowers are no exception. Crop rotation eliminates infestation due to overwintering larva. Keeping weeds around sunflowers under control eradicates habitats that encourage pests. Because some pests overwinter in dead plant material, turning under dead stems, composting them or destroying them removes a source of infestation for the following season.
Birds and Squirrels
Sunflower seeds are packed with energy, making them a favorite of birds and squirrels. If you are growing sunflowers for seed, however, you don't want your crop to be harvested by critters looking for a pick-me-up snack. The University of Illinois Extension recommends harvesting heads early, as soon as they turn from green to yellow, and allowing them to fully dry indoors in a dry location. Covering heads with paper sacks also minimizes damage by birds and squirrels.
In their 2010 sunflower pest management guide, the Kansas State University Extension offers tips to sunflower growers for managing pests on their plants. Correct identification of the pest is essential, and if you feel unprepared to do this on your own, contact your local extension office for help. "Proper timing of control measures cannot be emphasized enough," they add, advising sunflower growers to check their plants weekly for damage rather than waiting until damage has progressed.