Cucumber root rot and epidemic factors in Shaanxi Province, China

To elucidate pathogen and epidemic factors of cucumber root rot, two pathotypes of cucumber root rot were systematically investigated under solar greenhouse conditions by tissue isolation, single spore purification and re-inoculation in Shaanxi Province. The results show that the pathogens are different in different ecological regions, and the pathogen responsible for cucumber root rot in northern Shaanxi is identified as Phytophthora melonis, while that for Guanzhong region is Fusarium oxysporum. The pathogen colony grows normally within 10~30 ℃, and rapidly within 20~25 ℃. When temperature is over 30 ℃, the colony growth rate lowers. The prevalence of cucumber root rot are closely related to increased plantation areas, the number of years of continuous cropping, unreasonable crop rotation and flood irrigation. Environmental changes in cucumber fields constitute the main epidemic factor of cucumber root rot.