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ARS Home » Plains Area » Fargo, North Dakota » Edward T. Schafer Agricultural Research Center » Sunflower and Plant Biology Research » Research » Publications at this Location » Publication #177157
Title: INFLUENCE OF PLANTING DATE ON SUNFLOWER STEM WEEVIL (COLEOPTERA: CURCULIONIDAE) LARVAL DENSITY AND PARASITISM IN OILSEED AND CONFECTION SUNFLOWER IN THE WESTERN KANSAS

Author
item CHARLET, LAURENCE
item AIKEN, ROBERT - KANSAS STATE UNIVERSITY

Submitted to: Crop Management at www.cropmanagement.org
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/12/2005
Publication Date: 8/12/2005
Citation: Charlet, L.D., Aiken, R.M. 2005. Influence of planting date on sunflower stem weevil (Coleoptera: Curculionidae) larval density and parasitism in oilseed and confection sunflower in the western Kansas. Crop Management. Available: http://www.plantmanagementnetwork.org/cm

Interpretive Summary: The sunflower stem weevil infests stalks of cultivated sunflower and can cause lodging resulting in loss of the head prior to harvest. Our objective was to determine whether altered planting dates could reduce weevil numbers in confection and oilseed type sunflower in the central High Plains production region. We evaluated the impact of planting date by measuring larval numbers within sunflower stalks, larval parasite species present, and parasitism of the larvae. Trials were conducted at Colby, KS, from 1999 to 2001, with plots planted in four planting periods. Results were consistent among years and between the two sunflower types showing that later planting dates reduced weevil density in stalks. Weevil numbers in stalks from the first seeding period until the last had decreased by 10% to 50%. Fewer weevils were observed in oilseed than confection hybrids. Reduced densities in the stalk can aid the producer in preventing losses from lodged plants. Seven species of parasites attacked the weevil larvae. Rates of parasitism were low, but wasps were actively attacking the weevils throughout the growing season. Research showed that delaying planting until after the early and later May planting dates reduced weevil numbers in the central High Plains.

Technical Abstract: The sunflower stem weevil infests stalks of cultivated sunflower and can cause lodging resulting in loss of the head prior to harvest. Our objective was to determine whether altered planting periods could reduce weevil densities in confection and oilseed sunflower in the central High Plains production region. We evaluated impact of planting date by measuring larval density within sunflower stalks, larval parasitoid species present, and parasitization rates. Trials were conducted at Colby, KS, from 1999 to 2001, with plots seeded in four planting periods. Results were consistent among years and between the two sunflower types showing that later planting dates reduced weevil density in stalks. Weevil numbers in stalks from the first seeding period until the last had decreased by 10% to 50%. Fewer weevils were observed in oilseed than confection hybrids. Reduced densities in the stalk can aid the producer in preventing losses from lodged plants. Seven hymenopteran parasitoid species were reared from weevil larvae. Nealiolus curculionis (Fitch) and Neocatolaccus tylodermae (Ashmead) were the most common species. Parasitization rates were low, but wasps were actively attacking the weevil throughout the growing season. Research showed that delaying planting until after the early and later May planting periods reduced weevil densities in the central High Plains.