Published online by Cambridge University Press: 12 June 2017
Greenhouse and field experiments were conducted to compare the response of cucumber (Cucumis sativus L. ‘Ashley’), muskmelon (Cucumis melo L. ‘Delicious 51’), watermelon (Citrillus vulgaris L. ‘Charleston Grey’), and three winter squashes (Cucurbita moschata Duch. ex Poir. ‘Butternut’, Cucurbita pepo L. ‘Table Queen’, and Cucurbita maxima Duch. ‘Boston Marrow’) to 3-amino-2,5-dichlorobenzoic acid (chloramben) and six of its analogs (ammonium salt, amide, mixed salts, methyl ester, hydroxy propyl ester, and butoxy ethyl ester). There were little differences among the analogs except the amide was generally nontoxic to all test crops and weeds. Great differences in growth were noted among species. When chloramben was incorporated in the soil, cucumber and watermelon were very susceptible to all analogs except the amide. Muskmelon was tolerant of all analogs. Squashes exhibited variable susceptibility with ‘Butternut’ the least tolerant, ‘Table Queen’ intermediate, and ‘Boston Marrow’ quite tolerant of the analogs. Separation of exposure of the germinating and emerging seedling on the basis of root or shoot showed cucumber to be most susceptible to root exposure but also susceptible to shoot exposure. Muskmelon and ‘Boston Marrow’ squash were susceptible to root exposure but not to shoot exposure. Muskmelon was not susceptible to either hypocotyl or cotyledon exposure, but cucumber was susceptible to both these treatments. All three species were severely injured by postemergence sprays of chloramben.