Abstract: The continuous cropping of watermelon induces deterioiation of soil or disorder of nutrient, particularly reduces the nutrient of P, K and made the soil poor with micronutricnt such as Mg, Fe, Mn etc. In this case physiological barrier usually occurres, the plants show growth retard, resistance reduces, and the wilt and nematode diseases severely happen. So a great deal of plants die. Therefore diseases and physiological barrier are the main factors of continuous cropping barrie of watermelon. Utilization of complex pharmacon that mixed with fungicide soil amendment, macronutrient and micronutrient, will not only effectivley control the wilt, but also promote plant growth, made early-ripe for 2-3 days, increase the weight of single fruit by 9-12%, and raise the content of sugar by 1.5-2,0%.

Key words: Watermelon, Ccntinuous cropping, Physiological barrier, Pathological barrier