Author
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Charlet, Laurence |
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Submitted to: Proceedings Sunflower Research Workshop
Publication Type: Proceedings Publication Acceptance Date: 3/26/2002 Publication Date: N/A Citation: N/A Interpretive Summary: In September 2001, 406 sunflower fields were surveyed in North and South Dakota. Fields were sampled for yield and impact of weeds, diseases, and insects. Damage caused by red sunflower seed weevil, banded sunflower moth, and sunflower midge was measured. Evaluations were made by assessing visible damage to heads from midge and banded moth during the survey and from weevil and moth damage to seed collected from the fields. Banded sunflower moth damage was present in both North and South Dakota with the greatest levels in North Dakota. Infestation levels in North Dakota averaged 70% of heads both on the edge and within the fields. In South Dakota the state average was 50% of heads with webbing with the greatest levels in the NC and SW Districts. Seed damage averaged 7% in North Dakota with the greatest levels in the EC District at 10% damage. In South Dakota the state average was 3% with 7% in the NC and 1% in the NW Districts. Red sunflower seed weevil damage was greatest in South Dakota averaging 9%. The SW District had the greatest damage at 18%. In North Dakota average damage from seed weevil was 4%, but 8% of seeds in the SE District showed damage. Sunflower midge was detected in all areas of North Dakota except the NW District with a state average rating of 0.4 on a scale of 0-5. In South Dakota only 3 of 6 Districts had evidence of sunflower midge. The survey showed that banded moth was a serious pest in 2001, and is causing damage throughout North Dakota with infestations extending into NC South Dakota. Red sunflower seed weevil, although not a major problem for many years, has become more numerous, especially in South Dakota, and has reached levels that can cause yield reductions. The sunflower midge did not have as large an impact as the other insects. Technical Abstract: In September 2001, 406 sunflower fields were surveyed in North and South Dakota. Fields were sampled for yield and impact of weeds, diseases, and insects. Damage caused by red sunflower seed weevil, banded sunflower moth, and sunflower midge was measured. Evaluations were made by assessing visible damage to heads from midge and banded moth during the survey and from weevil and moth damage to seed collected from the fields. Banded sunflower moth damage was present in both North and South Dakota with the greatest levels in North Dakota. Infestation levels in North Dakota averaged 70% of heads both on the edge and within the fields. In South Dakota the state average was 50% of heads with webbing with the greatest levels in the NC and SW Districts. Seed damage averaged 7% in North Dakota with the greatest levels in the EC District at 10% damage. In South Dakota the state average was 3% with 7% in the NC and 1% in the NW Districts. Red sunflower seed weevil damage was greatest in South Dakota averaging 9%. The SW District had the greatest damage at 18%. In North Dakota average damage from seed weevil was 4%, but 8% of seeds in the SE District showed damage. Sunflower midge was detected in all areas of North Dakota except the NW District with a state average rating of 0.4 on a scale of 0-5. In South Dakota only 3 of 6 Districts had evidence of sunflower midge. The survey showed that banded moth was a serious pest in 2001, and is causing damage throughout North Dakota with infestations extending into NC South Dakota. Red sunflower seed weevil, although not a major problem for many years, has become more numerous, especially in South Dakota, and has reached levels that can cause yield reductions. The sunflower midge did not have as large an impact as the other insects. |