Additional evidence is presented that Pythium irregulare causes seed decay, pre-emergence and damping-off of watermelon seedlings. Root necrosis which results in stunting or death of the seedlings is reported as an additional symptom. Seedling rot is used as a descriptive term for the composite effects of P. irregulare;Fusarium bulbigenum var. niveum and Rhizoctonia sp. cause similar damage to watermelon seedlings. A significant reduction of emergence was not obtained with F. bulbigenum var. niveum except when the seedlings were grown in heavily "wilt infested" soil. Even then the stand reduction was only slight to moderate. The percentage of isolates of Rhizoctonia sp. obtained from diseased seedlings grown in the field has been low. A large number of isolates of F. bulbigenum var. niveum and other Fusarium spp. were obtained from seedlings which showed no evidence of disease. Fusarium is an omnipresent fungus and appears to rapidly overrun Pythium in the roots of plants;A large percentage of isolates obtained from diseased seedlings grow in the field have been P. irregulare. Isolates were obtained from seedlings within thirty days from sowing and not more than 16 to 20 days after emergence. Pythium appears to attack only the seed or the young seedling. Seeds planted early in the season may escape seed decay but still succumb as seedlings after emergence;Seedling stands are reduced to about 5 percent in soil infested with Pythium irregulare;Trichoderma viride has been isolated frequently from seed coats and roots of watermelon seedlings;Germination of watermelon seeds was reduced when planted in natural "wilt infested" soil at various moisture levels held for 7 days at 45°F prior to placement in the greenhouse for germination. Germination was much less at the higher moisture levels. Pythium irregulare was isolated from embryos after 7 days at 45°F;Arasan, Spergon and Phygon used as seed treatments resulted in good increases in final stand with seed of high, medium and low percentage germination. Good seed germinated three to five days earlier than poor seed.