Study On Pathogenic Fungi Of Asparagus Root Rot

Samples of root rot diseased asparagus were collected from Shandong province and Fujian province in China in 2003. Pathogenicities of isolates obtained from those samples were tested according to Koch's postulates. The results showed that Fusarium spp., including F. oxysporum, F. solani, F. proliferation, and to a lesser extent F. semitectum, were the dominant fungi isolated. So far very few isolates belonging to Penicillium sp. and Alternaria sp. were obtained.F. solani was recovered at the highest frequency from the root rot diseased asparagus collected from Shandong province. F. oxysporum and F. proliferation had higher frequency than F.semitectum. Disease-causing abilities of R oxysporum and R proliferation were significantly stronger than that of F. semitectum and F. solani in vitro agar-test-tube assay. In complex infection test asparagus seedlings inoculated with F.proliferatum compounded respectively with F.semitectum and F. solani had higher disease rating class than those inoculated with other compoundings of Fusarium spp. The high frequency of isolation and the strong virulence of F. proliferatum and R solani from Shandong province indicated that complex infection of F. proliferatum and F. solani caused crown and root rot of asparagus in Shandong province.F. oxysporum was recovered at the highest frequency from the root rot diseased asparagus collected from Fujian province. Disease-causing ability of F. oxysporum and F. proliferatum isolate were significantly stronger than that of F.semtectum and R solani in vitro agar-test-tube assay. The high frequency of isolation and the strong virulence of F. oxysporum showed that R oxysporum was the most important pathogen associated with asparagus decline in Fujian province.Samples of asymptomatic asparagus were collected from Shandong province and Fujian province in China in 2003. The results of isolation and identification showed that F. proliferatum was the dominant fungi isolated from asymptomatic samples collected from Shandong province and F. oxysporum from Fujian province. Pathogenicity test of a part of isolates from Shandong province showed that F. proliferatum, R oxysporum and R solani were pathogenic to asparagus seedling and the abilities of causing asparagus root rot disease of the three Fusarium spieces were not significantly different. The high isolation frequence and pathogenicity showed that F. proliferatum was the most important potential pathogen in shandong province.