Hyphal anastomosis was used to find relatedness of two isolates from different locations, Rh1534 from Eloy and Rh1542 from Litchfield (Table 1). A known isolate of Thanatephorus cucumeris (Rhizoctonia solani) from diseased cotton seedlings in a field near the Eloy watermelon field was used as a tester strain (Rh1549). It was previously isolated and identified by DNA sequencing (Table 2). Using the slide technique of Kronland and Stanghellini (1988), isolates Rh1534 and Rh1542 anastomosed with themselves and with each other but not with isolate Rh1549.