Abstract:We studied on the effect of decaying substances on Fusarium oxysporum mycelia growth, spore emergence, seed emergence, radicle growth, characters of seedling and Fusarium wilt, through method of plate growth test, spore germination test, radicle growth inhibition test, conductivity method and pot experiment. The results showed that the much higher cucumber wilt disease incidented, the more significantly the diseased survival inhibited growth of the next decaying stubble. Compared with CK, quantity of spores of healthy plants, mild diseased plants and severe diseased plants increased 27.29%, 50.05% and 44.88%, respectively. Spore emergence ratio increased 15.91%-38.94% under treatments of healthy plants’ decaying substances. Cucumber decaying substances of different concentrations influenced radicle growth, and fibres decreased 6.15%-27.10%. Cell membrane permeability increased 76.03%-89.96% under treatments of decaying substances of heavy diseased plants, which concentrations were different. Decaying substances of heavy diseased plants those concentration were high, decreased emergence of cucumber 53.15%, while ratio of diseased plants increased 55.11%. Therefore, allelopathy of diseased roots’ decaying substances might be important reason of serious disease of cucumber continuous cropping.