ARS | Publication request: POTENTIAL FOR SELECTING POWDERY MILDEW RESISTANT GERMPLASM IN WATERMELON

Submitted to: Horticulture Industries Show
Publication Type: Proceedings
Publication Acceptance Date: February 2, 2001
Publication Date: February 2, 2001
Citation: Davis, A.R., Bruton, B.D., Pair, S.D. 2001. Potential for selecting powdery mildew resistant germplasm in watermelon. Proceedings of 20th Horticulture Industries Conference. 20:97-100.

Interpretive Summary: Powdery mildew is a fungal disease that affects many crops with often devastating results. Historically, watermelon have been resistant to the disease although outbreaks were confirmed last year in OK, TX, FL, CA and SC. This disease has epidemic potential, especially in the south central and southwestern United States. Information on the race of the powdery mildew fungus involved is presently unknown. In this study we screened watermelon genotypes seeking innate resistance to powdery mildew. Crosses were made in order to study the inheritance of resistance. Results of our study demonstrated that resistance to powdery mildew exists in the Plant Introduction Germplasm Collection. This information will be useful in transferring this resistance into commercial watermelon cultivars.

Technical Abstract: Powdery mildew has been a devastating disease for many crops since the 1800's. All cucurbit crops are susceptible to the disease. Watermelon have typically been resistant to this disease in the past although outbreaks were confirmed last year in OK, TX, FL, CA and SC. Powdery mildew on watermelon is an emerging disease in the U.S. with epidemic potential. We have screened Citrullus lanatus for resistance to a virulen race of Sphaerotheca fuliginea. Results of our study demonstrated that tolerance to powdery mildew exists in the Plant Introduction Germplasm Collection. However, none of the C. lanatus screened were 100% resistant to the disease. The information gained from this study will be useful in transferring powdery mildew tolerance into commercial watermelon cultivars thus reducing the number of fungicide applications necessary for the control of powdery mildew on watermelon.