48th TWC, Tob. Work. Conf., 2018, abstr. 44

Fungicide selection and timing for control of Phytophthora nicotianae in flue-cured tobacco

North Carolina State University, Raleigh NC USA

Selection of fungicides at each application, transplant water, 1st cultivation, and layby, is an important step to manage black shank of tobacco, caused by Phytophthora nicotianae. Soil type and texture may influence efficacy of soil-applied fungicides. Four naturally-infested fields containing different soil types were selected two assess timing of three different fungicides, Orondis Gold, Ridomil Gold, and Presidio. Fungicides were applied at label rates at a combination of one or all timings, transplant water, 1st cultivation, and layby. Disease ratings were taken at regular intervals throughout the growing season to assess efficacy of fungicides. Black shank was first detected at week six in Yadkinville and week eight in Rocky Mount. No phytotoxicity was observed with any treatments applied. In Rocky Mount, the AUDPC of Orondis + Presidio + Ridomil, Orondis + Ridomil + Presidio, Orondis, and Ridomil + Ridomil + Ridomil treatments were significantly different compared to the non-treated control, whereas treatments Orondis + Presidio + Ridomil, Orondis + Ridomil + Presidio, Orondis + Ridomil, Orondis + Presidio, Ridomil + Ridomil, Ridomil + Ridomil + Ridomil and Orondis + Presido after transplant treatments were significantly different from the control at Yadkinville. (Reprinted with permission)