INTERACTION OF COLLETOTRICHUM-ORBICULARE WITH THRIPS AND APHID FEEDING ON WATERMELON SEEDLINGS

Watermelon (Citrullus lanatus (Thunb.) Matsum. & Nakai) seedlings were either untreated or treated as follows: inoculated only with the fung us Colletotrichum orbiculare (Berk. St Mont.) Arx, infested only with thrips (Thrips tabaci Lindeman) or aphids (Aphis gossypii Glover), or infested with either insect before or after inoculation with C. orbicu lare in a greenhouse. Plant heights, dry weights, and percent lesion a rea on cotyledons, true leaves, and the whole plant (cotyledons and le aves) were determined. When thrips were the challenge insects infested plants were among the shortest, but also the heaviest. Percent lesion area on cotyledons, leaves, and the whole plant was significantly red uced (P less than or equal to 0.05) on plants infested with thrips bef ore inoculation with C. orbiculare compared with plants receiving only C. orbiculare and plants infested after inoculation with C. orbicular e. With aphids as the challenge insect plant heights and dry weights w ere not affected by treatment. Percent lesion area on plants infested with aphids before, or after, inoculation with C. orbiculare was signi ficantly lower than on plants inoculated with C. orbiculare only. Publ ished by Elsevier Science Ltd.