Management of bacterial wilt of tomato with a combination of grafting and a systemic acquired resistance inducer
S. KUNWAR (1), M. L. Paret (2), J. B. Jones (1), L. Ritchie (2), J. H. Freeman (2), S. M. Olson (2). (1) Plant Pathology Department, University of Florida, Gainesville, FL, U.S.A.; (2) NFREC, University of Florida, Quincy, FL, U.S.A.
Field trials and greenhouse studies were conducted in Florida from 2012-2013 to determine the integrated effect of grafting and application of acibenzolar-S-methyl (ASM), a systemic acquired resistance (SAR) inducer, for control of bacterial wilt disease of tomato caused by <i>Ralstonia solanacearum</i>. In greenhouse experiments, ASM (50 mg/l) was applied twice either as foliar spray or as soil drench before inoculation. Soil application of ASM significantly reduced disease severity on a susceptible tomato cultivar (BHN 602) as compared to foliar treated or the untreated control (P≤0.05). Similarly, in the field, a single drip application of ASM (50 mg/l) before transplanting and four weekly drip applications of ASM (0.5 oz/A) after transplanting significantly reduced disease incidence in BHN 602 (P=0.0045), but did not significantly improve yield (P=0.0057) relative to the untreated control. Grafting (BHN 998 rootstock and BHN 602 scion), alone or in combination with drip application of ASM (0.5 oz/A), provided significantly better disease control and yield relative to the untreated control. In contrast, foliar ASM application combined with grafting provided a marginal increase in disease incidence and significantly reduced yield in one of the field trials as compared to the untreated grafted control (P<0.0001). The combination of grafting and ASM application via drip, however, was statistically equivalent to grafting in controlling the disease and improving yield.
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