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<OL> <LI> Develop improved resistance to root-knot nematodes in pepper and watermelon. </li> <LI> Identify and develop improved resistance to diseases in cucurbits, e.g. powdery mildew, downy mildew, Phytophthora blight, and watermelon vine decline.</li> <LI> Elucidate virulence parameters of selected plant pathogen populations and develop integrated methodologies for managing cucurbit diseases. </li></ol>
APPROACH: Develop root-knot nematode-resistant sweet banana, sweet cherry, pimiento, and Cubanelle type peppers using backcross breeding procedures. Determine inheritance of resistance to root-knot nematodes (Meloidogyne incognita) in watermelon in greenhouse studies, and use techniques such as single sequence repeat (SSR) and sequence-related amplified polymorphism (SRAP) to develop molecular markers linked to root-knot nematode resistance genes in watermelon. Screen watermelon and melon germplasm for resistance to Phytophthora capsici and develop resistant germplasm. Screen bottle gourd (Lagenaria siceraria) plant introductions for resistance to powdery mildew in the greenhouse and develop resistant germplasm for use in rootstock breeding program. Screen watermelon plant introductions for resistance to watermelon vine decline, and evaluate strategies and develop integrated methodologies to manage watermelon vine decline in field tests. Identify prevalent races of powdery mildew using melon host differentials and determine their virulence on other selected cucurbit species in greenhouse and field studies. Determine genetic variability in the downy mildew pathogen (Pseudoperenospora cubensis) isolated from watermelon and cucumber using host differentials and molecular markers.