Developed Improved Management Practices and Elite Cotton Germplasm with Pest Resistance for the Mid-Southern Usa
Crop Genetics Research Unit
2011 Annual Report
1a.Objectives (from AD-416)
Develop management practices for pest control in cotton. Evaluate and develop elite cotton germplasm for yield, quality and pest resistance. Develop improved agronomic practices for cotton production in an environment of changing technology.
1b.Approach (from AD-416)
Determine response of pests to available control practices. Evaluate response of cotton to management practices such as planting date, fertility practices and plant growth control. Measure pest response to application of control measures. Develop elite cotton germplasm and measure response in state yield tests. Transfer genes for resistance to diseases, insects and nematode into Delta-type cotton using traditional and molecular-assisted practices. Test alternative means to control pests with tolerance to normal control practices.
A series of three trials in different locations were conducted comparing the efficacy of seed treatment nematicide-insecticides to manage the reniform nematode. Each of these trials were planted as early as possible and at the regular planting time. The early planting time was included because of reports that early planting was a method of reducing nematode populations. Reniform nematode numbers were all above the threshold (1,000 per pint of soil) in all of the trials at planting. Reniform nematode numbers at planting tended to be lower in the early planted trials. However, nematode numbers were high at harvest on both planting dates. Nematode numbers, reproductive factors (Rf), seedling disease, and seed cotton yields were not correlated with seed insecticide, or nematicide treatment. In two of the trials, some of the seed cotton yields were higher following nematicide and insecticide treatment. This indicates that nematodes may be predisposing the plants to seedling disease. A trial was conducted to determine the response of 18 cotton varieties to the biological nematicide Votivo. About one-third of the plots were below the nematode threshold level of 1,000 nematodes per pint of soil at planting. Nematode numbers at planting ranged from 674 to 2,310 reniform nematodes per pint of soil at planting. There were no significant differences in nematode numbers between the untreated and Votivo treated seed at planting, 10 weeks after planting and at harvest. There were no significant differences in the Rf at 10 weeks or at harvest. There were significant differences between the treatments in percent seedling survival 2 and 4 weeks after planting. There were significant differences in seed cotton yields between the different treatments. Several varieties had significantly higher stands counts and or yields when they were treated with Votivo. Since all of the seed were treated with a seed treatment fungicide, it is possible that Votivo treated seedlings were less sensitive to seedling diseases and that the reniform nematodes predisposed the untreated seed to seedling disease. ADODR used site visit, email and telephone conferences to monitor activities of the project.