Control of target spot of tomato with fungicides, systemic acquired resistance activators, and a biocontrol agent

Control of target spot of tomato, caused by the fungus Corynespora cassiicola (Berk. & Curt.) Wei., was studied in three seasons in southern Florida, USA. The strobilurin fungicide azoxystrobin and a combination product of mancozeb and fumoxate provided excellent control of target spot. In these treatments, accumulated disease severity values were only 10-15% of those in the untreated control and marketable yields were doubled. Excellent disease control also was achieved with acibenzolar-S-methyl, a systemic acquired resistance activator (SAR). This compound reduced defoliation of tomato plants by 42% compared to the control. An experimental compound, BAS 510 02, provided good control of target spot, reducing defoliation by 40% and increasing marketable yields by 34%. Harpin protein and Bacillis subtilis strain QST 713 were not effective for control of target spot.