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Poster: Biology & Disease Mgmt: Chemical Control


Combined Application of Bacillus amyloliquefaciens ZY-9-13 with Fungicides for Control of Tobacco Black Shank
W. MU (1), J. XI (1), C. XUE (1), L. HU (1), J. SONG (1) (1) Zhengzhou Tobacco Research Institute of CNTC, China

Tobacco black shank is a devastating soil borne disease caused by Phytophthora parasitic var. nicotianae, which greatly reduces tobacco yield and quality. Fungicides, such as metalaxyl, dimethomorph and mancozeb, have been widely used to prevent and control this disease. Intergrated biological and chemical control can release pressures from environment and delay emergence of fungicide resistance. Bacillus amyloliquefaciens ZY-9-13 has good control effect to tobacco black shank in our previous studies. In this research, we 1) assessed sensitivities of P. nicotianae to metalaxyl and dimethomorph, 2) mixed B. amyloliquefaciens ZY-9-13 and fungicide metalaxyl, dimethomorph, mancozeb in order to provide an alternative disease control option. The baseline sensitivities of P. nicotianae to metalaxyl and dimethomorph were described by unimodal curves, with mean EC50 values of 0.0664(±0.0282) and 0.3502(±0.0332) µg/ml, respectively, which can be used for detection of resistance isolates. Laboratory tests showed that fungicide mixture of metalaxyl, dimethomorph and mancozeb had additive effect, and the inhibition ratio of ZY-9-13 to fungicide mixture was less than 10% even at high concentration. The intergrated biological and chemical control showed a synergistic action. In the field trial, disease control with the combination of B. amyloliquefaciens ZY-9-13 and fungicide mixture was 79.76%~86.90%, which was greater than with ZY-9-13 or fungicide alone.