Gummy stem blight caused by Didymella bryoniae (Auersw.
Gummy stem blight was first described by Fautrey and Roumeguere in France as the disease caused on cucumber (Cucumis sativus L.
Gummy stem blight on watermelon plants is evident as crown blight, stem cankers, and extensive defoliation, with symptoms observed on the cotyledons, hypocotyls, leaves, and fruit (Maynard and Hopkins, 1999).
Adequate control of gummy stem blight through fungicide applications (Keinath, 1995, 2000) and good cultural practices (Keinath, 1996; Rankin, 1954) is difficult, particularly during periods of frequent rainfall when relative humidity remains high for a long period.
Methods of seedling evaluation for resistance to gummy stem blight have been reported in watermelon (Boyhan et al.
In previous studies, there were genetic differences for gummy stem blight resistance among commercial cultivars of watermelon.
However, they were much less resistant to gummy stem blight than the resistant parents PI 189225 and PI 271778.
The objective of this study was to evaluate the available USDA-ARS watermelon germplasm collection for resistance to gummy stem blight using commercial cultivars as reference points,
The checks were 51 watermelon cultivars, along with a set of seven cucumber cultivars, to provide reference points for gummy stem blight resistance.
The complete dataset for all the 1332 cultigens tested for resistance to gummy stem blight was submitted to the Germplasm Resources Information Network (http:// www.