The Response of Cotton Varieties to Bacterial Blight in South Texas

Wednesday, January 8, 2020
JW Grand Salons 7-8 (JW Marriott Austin Hotel)
Thursday, January 9, 2020
JW Grand Salons 7-8 (JW Marriott Austin Hotel)
Friday, January 10, 2020
JW Grand Salons 7-8 (JW Marriott Austin Hotel)
Srinadh Kodali , Texas A&M University - Kingsville
Greta Schuster , Texas A&M University Kingsville
Enrique Gino Medrano , USDA-ARS
Alinna Umphres , Texas A&M University - Kingsville
Bacterial blight of cotton, caused by Xanthomonas citri pv. malvacearum (Xcm), is a pathogen of concern in cotton production. Bacterial blight of cotton causes leaf defoliation and boll shed which results in yield loss. Bacterial blight has been controlled effectively for more than 50 years by breeding for host plant resistance, however recent outbreaks of the disease have raised concerns among growers and scientists about the possible development of new Xcm races that could cause disease in commercially available resistant varieties. The objective of this study was to evaluate cotton varieties for disease incidence and severity when inoculated with Xcm isolated from Texas cotton fields.  The study was conducted in 2019 at the Texas A&M University-Kingsville Research Farm. The study consisted of one resistant variety, NG 5711B3XF and two susceptible varieties NG 3406 B2XF, and DP 1725B2XF. Followed by four moderately susceptible varieties NG 3729, DP 1646B2XF, DP 1845 B3XF and DP 1948B3XF. All the varieties were inoculated with Xcm at match head and candle stages at a concentration of 106 per ml and Silwet L-77®, using a CO2 backpack sprayer. Data was collected on disease incidence and severity at 7 days after inoculation.  A statistically significant difference was observed between the varieties both for disease incidence and severity. Results indicate that varieties known to be resistant were resistant and those known to be susceptible were susceptible against Xcm. Susceptible varieties had up to 100% more disease incidence than those resistant ones. The results found in this study indicate that the commercial cotton varieties tested remain resistant to Xcm.