Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 4/9/2007
Publication Date: 7/10/2007
Citation: Kousik, C.S., Ling, K., Levi, A. 2007. Tolerance to Cucurbit Powdery Mildew in USDA Bottle Gourd (Lagenaria siceraria) Plant Introductions (PI). Phytopathology. 97:S60.
Technical Abstract: Powdery mildew (Podosphaera xanthii) can cause severe damage to cucurbit crops grown in open fields and greenhouses. Bottle gourd plants (Lagenaria siceraria) are being used throughout the world as rootstocks for grafting watermelon. In recent years, there has been a growing interest in the USA in grafting watermelon plants onto various cucurbit rootstocks. Although, gourd plants are beneficial, they may still be susceptible hosts to different soil and foliar diseases. Bottle gourd PIs resistant to diseases and pests can be valuable in rootstock breeding programs. We evaluated 209 U.S. Plant Introductions (PI) of L. siceraria for tolerance to powdery mildew in the greenhouse. Young seedlings were inoculated by dusting powdery mildew spores of melon race 1 on the leaves and cotyledons. Plants were rated two weeks after inoculation on a 1-9 scale of increasing disease severity. Significant variability in level of tolerance to powdery mildew on plants within PI were observed. Fourteen (7.0%) of the 209 PIs tested were tolerant to powdery mildew (rated <5 on the 1-9 scale). The watermelon cultivar Mickey Lee was susceptible in the various trials (rated >7). A few L. siceraria PIs had little or no obvious PM infestation. These PIs are being further evaluated to confirm their tolerance to powdery mildew.