SCREENING FRESH-MARKET TOMATOES FOR SUSCEPTIBILITY TO CATFACING WITH GA3 FOLIAR SPRAYS

The blossom-end scarring of tomato fruit caused by exposure of the pla nt to cool weather during ovary formation, commonly termed catfacing, can also be induced by GA3 foliar sprays. To determine if GA3 treatmen t could serve as a cultivar screening tool to identify lines susceptib le to the disorder, we compared the catfacing incidence in 14 fresh-ma rket tomato cultivars after GA3 sprays and in nontreated controls in t wo field experiments. In 1 year, removal of the plant's apex was also imposed. GA3 sprays (22 mum twice, applied 1 week apart to tomato seed lings almost-equal-to 5 weeks old) increased catfacing incidence in bo th years and accentuated cultivar differences in the disorder. Topping did not increase catfacing significantly. The cultivars Valerie, Sunr ise, and Basketvee were least affected by catfacing in the experiments , while 'Starfire', 'New Yorker', and 'Olympic' had the highest percen tage of catfaced fruit. The GA3 screening method shows promise for ide ntifying cultivar differences in susceptibility to blossom-end scarrin g. Chemical name used: gibberellic acid (GA3).