2017 ASHS Annual Conference

Watermelon is a major cucurbitaceae and it is known as a representative of fruits in summer season. These days the consumer prefer middle and small type watermelon to large type. It is result from decrease of family members and the small type watermelon have easy movement. But there has been no research on cultivation and occurrence of diseases and insect pests in small type watermelon in korea. So we investigated the occurrence pattern of diseases and insect pests, effect of organic materials to control against watermelon powdery mildew in small type watermelon. The result of this study, the small type watermelon was damaged by Didymella bryoniae, Podosphaera xanthii, Aphis gossypii, Tetranychus urticae, thrips, Spodoptera exigua and Spodoptera litura. Among them, the occurrence of Podosphaera xanthii, Tetranychus urticae and thrips was high. Diseased leaf rate by Podosphaera xanthii was 27∼99.3% in three small type watermelon cultivars in the middle of June. The number of Tetranychus urticae per leaf was high from 79.9 to 111 in three small type watermelon cultivars in the middle of June. It showed high number of thrips captured by yellow and blue sticky trap. That of yellow sticky trap was 407 and that of blue sticky trap was 774 in the middle and first of June respectively. On the other hand, the occurrence of rest diseases and pests except Podosphaera xanthii, Tetranychus urticae and thrips was low. The experiment of control effect against powdery mildew using mayonnaise, oleic acid and three organic materials showed control efficacy over 60% in the treatment of material containing sodium bicarbonate 80%, mayonnaise and extract of Rheum palmatum 1% + ethyl alcohol 30%. The highest control efficacy was 83% in the treatment of material containing sodium bicarbonate 80%. From this study, we had a information of the occurrence pattern of diseases and insect pests in small type watermelon and the treatment of material containing sodium bicarbonate 80% was very effective for controlling against powdery mildew.