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United States Department of Agriculture

Agricultural Research Service

Title: Comparison of Two Midge Damage Rating Systems.

Authors
item Schmidt, Gene - NORTH DAKOTA STATE UNIV
item Brewer, Gary - NORTH DAKOTA STATE UNIV
item Charlet, Laurence

Submitted to: Proceedings Sunflower Research Workshop
Publication Type: Proceedings
Publication Acceptance Date: January 29, 1999
Publication Date: N/A

Interpretive Summary: The sunflower midge is a pest of sunflower in the northern Plains production region. Feeding by the midge larvae causes distortions and cupping of the sunflower head that results in varying degrees of economic damage. Over the years different systems of rating damage have been developed to screen sunflower germplasm for resistance to this pest. Two different systems are evaluated in this study. The first rating system compares levels of damage at head maturity and the second rating system is a visual estimate of the percentage of ray petals missing. The second system was designed to make early damage ratings in order to select plants to be used to make crosses that same season. Although both systems can be used to evaluate head damage caused by the midge, the method that is based on missing ray petals is only an estimate of potential damage and does not always accurately predict final damage. It could result in retention of susceptible germplasm or conversely, the loss of resistant germplasm from the breeding pool.

Technical Abstract: The sunflower midge is a pest of sunflower in the northern Plains production region. Feeding by the midge larvae causes distortions and cupping of the sunflower head that results in varying degrees of economic damage. Over the years different systems of rating damage have been developed to screen sunflower germplasm for resistance to this pest. Two different systems are evaluated in this study. The first rating system compares levels of damage at head maturity and the second rating system is a visual estimate of the percentage of ray petals missing. The second system was designed to make early damage ratings in order to select plants to be used to make crosses that same season. Although both systems can be used to evaluate head damage caused by the midge, the method that is based on missing ray petals is only an estimate of potential damage and does not always accurately predict final damage. It could result in retention of susceptible germplasm or conversely, the loss of resistant germplasm from the breeding pool.

Last Modified: 10/24/2014
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