46th TWC, Tob. Work. Conf., 2014, abstr. 37

Integrated black shank management on flue-cured tobacco

University of Georgia, Department of Plant Pathology, CPES, 2360 Rainwater Road, Tifton, GA 31793, USA

Three tobacco cultivars having different sources of resistance to Phytophthora nicotianae, NC 71, SP 225, and K 326 were untreated or treated with Ridomil Gold (1 pt/A X3), Zorvec (QUG 42) (19.2 oz/A X3),or Persidio (4 oz/A X3) in a Tobacco Black Shank Nursery. NC 71 has php gene for resistance to Race 0; SP 225 has php gene for resistance to Race 0 and multigenic FL 301 resistance to both Race 0 and Race 1; and K 326 has only low resistance to Race 0 and Race 1. Test materials were applied at plant, 1st cultivation and layby. Plots were evaluated for vigor, growth, disease incidence and yield. Vigor ratings and height measurements made during the season indicate no phytotoxicity with the rates and application timing of the fungicides. All of the chemical applications reduced disease when compared to the untreated cultivars. NC 71, K 326, and SP 225 had 51%, 68%, and 41% disease in the non-treated check. NC 71 had 14%, 7%, and 26% disease with Ridomil Gold, Zorvec and Presidio, respectively. K 326 had 29%, 33%, and 33% disease with Ridomil Gold, Zorvec, and Presidio respectively. SP 225 had 20%, 2%, and 6% disease with Ridomil Gold, Zorvec, and Presidio respectively. We suggest that some cultivar/fungicide combinations may be better than others to manage tobacco black shank. The availability of new fungicides with different chemistry and cultivars with different sources of resistance will provide growers with better management strategies for black shank. (Reprinted with permission)