Canola yield deficit from pods damaged by the cabbage seedpod weevil Ceutorhynchus obstrictus (Marsham)
Ernst Cebert, email@example.com, Rufina N. Ward, firstname.lastname@example.org, and Kenneth E. Ward, email@example.com. Alabama A&M University, Department of Plant & Soil Science, P. O. Box 1208, Normal, AL
Winter-type canola (Brassica napus) shows promise as an alternative to winter wheat in rotation with soybeans in the southeastern U.S. However, the cabbage seedpod weevil (CSW), Ceutorhynchus obstrictus (Marsham), is of concern as a potentially important pest that could limit seed production. CSW larvae feed on developing seeds within seedpods and eventually leave the pod to pupate, producing a conspicuous exit hole. A study was conducted during the 2001-2002 and 2002-2003 growing seasons to determine the degree of pod damage caused by CSW and its relationship to canola seed yield. Whole plant samples were collected from three replications of five cultivars prior to seed harvest. Seedpods were examined and the number of larval exit holes were counted. Seedpods were classified into four categories based on degree of CSW damage: 0 exit holes (no damage), 1 exit hole, 2 exit holes and 3+ exit holes. Results indicate that degree of CSW damage varies with cultivar. However, it should also be noted that the impact of CSW damage on seed yield also varies among cultivars. These results are further discussed.