Clomazone selectivity among six cucurbit crops

Abstract

To determine clomazone tolerance of cucurbit crops, at different rates (0.3, 0.45, 0.6 and 0.9 kg ai ha(-1)) and to evaluate weed control efficacy of those treatments, six field studies were conducted in the 1998-1999 season. Clomazone at 0.45 kg ai ha(-1) provided an excellent weed control (>90%) compared with the untreated plots. Yield and number of fruit per plot in all crops were not affected (p <= 0.05) by clomazone treatment regardless of the rate used, except in honeydew (Cucumis melo L. vat. inodorus Naud). As for leaf injury, with the exception of zucchini (Cucurbita pepo L.) and winter squash (C. maxima Duch, Ex. Poiret), all other crops [cucumber (Cucumis sativus L.), honeydew (Cucumis melo L. vat. inodorus Naud), watermelon (Citrullus lanatus Thunb. Matsumara and Nakai) and cantaloupe (Cucumis melo L. vat. reticulatus Naud), exhibited leaf bleaching 10 d after treatment; cantaloupe and watermelon were the least tolerant crops. However, the bleaching effect was transient and did not affect yield. Clomazone can be used selectively as a preemergence herbicide on winter squash, zucchini and cucumber at rates ranging from 0.3 to 0.9 kg ai ha(-1); and on honeydew, watermelon and cantaloupe from 0.3 to 0.6 kg is ha(-1).