Control of sunflower moth larvae and damage to sunflower seeds
Investigations on the control of the sunflower moth, Homoeosoma electellum (Hulst), conducted over several seasons indicated that certain insecticides can satisfactorily reduce sunflower head and seed damage when multiple applications are properly timed. Of the commercially available materials tested, endosulfan and diazinon afforded the most efficient control. Treatments must begin at onset of bloom, and three applications at intervals of 5 to 7 days gave optimum results. Two applications were the minimum required, but three were generally needed because of the fast head growth, quick flowering, and concentrated egg deposition during this period. The biological agent Bacillus thuringiensis, was found unsatisfactory for control. Only GS 13005 (of several new experimental chemicals tested) gave outstanding control. One larva could severely damage nine or more seeds, and moderate to severe infestations of 12 to 24 larvae per head caused serious seed loss. Pesticide control was usually necessary, but the actual amount of damage varied from season to season.