Abstract:In order to identify the species of pathogenic fungi responsible for a novel soybean root rot in Guangdong， understand their biological characteristics， and screen effective fungicides to control the disease， the pathogenic fungi were isolated from the roots and stem bases of infected soybean plants using a tissue isolation method.The fungi were identified based on their morphology and through a combined phylogenetic analysis of 3 genes （rDNA-ITS， TEF-1α， and RPB2）.Subsequently， the isolated pathogenic fungi were inoculated into the roots and stem bases of the original soybean cultivar Guixia No.2， either alone or in combination， to determine their pathogenicity.The effects of various media， temperatures， carbon and nitrogen sources， pH， light and fungicides on mycelial growth， as well as the lethal temperatures of the pathogens’ conidia were measured.The results showed that two fungal strains with different characteristics were isolated from the roots and stem bases of infected soybean plants， identified as Fusarium neocosmosporiellum and F. falciforme， respectively.The later was first reported in soybeans in Guangdong， China.Inoculation experiments showed that both fungal strains， whether individually or in combination， could cause symptoms similar to those of soybean root rot disease observed in the field.F. neocosmosporiellum exhibited the fastest growth at 28 ?C and pH 7， effectively using a variety of carbon and nitrogen sources， with lactose and peptone identified as the most effective carbon and nitrogen sources， respectively.The lethal temperature for conida was 51 ?C for 10 min.In contrast， F. falciforme showed the highest growth rate at 25 ?C and pH 7， with a strong capacity for using carbon and nitrogen sources.Lactose， sucrose， and maltose were the most effective carbon sources， while peptone was the optimal nitrogen source.The lethal temperature for conidia was 54 ?C for 10 min.Different light treatments did not affect the mycelial growth of either strain.The fungicide prochloraz exhibited the strongest inhibitory effect on both strains.In summary， the pathogenic fungi responseble for the novel soybean root rot disease in Guangdong were F.neocosmosporiellum and F. falciforme.These two fungi demonstrate strong environmental adaptability and sensitivity to prochloraz， making it the preferred choice for controlling the novel soybean root rot disease.

Abstract:Four isolates of the anthracnose pathogen were isolated from postharvest banana fruits displaying anthracnose symptoms by using tissue isolation technique. The differences in mycelial growth rate,conidial germination, appressorium formation and pathogenicity of the four isolates were compared under the same conditions. The results showed that there was no significant difference in the mycelial growth rate,but the percentages of conidial germination and appressorium formation, and the pathogenicity of isolate X4 were significantly higher than those of the other 3 isolates. The isolate X4 was identified as Colletotrichum musae based on the classical morphological taxonomy combined with the technique of ITS sequence analysis. Meanwhile, the effects of temperature, illumination and pH value on the mycelial growth, conidial germination and appressorium formation of isolate X4 were investigated. The results indicated that the temperatures for the mycelial growth were ranged from 10-35 ℃, with an optimum of 28 ℃ and the suitable temperatures for conidial germination and appressorium formation were from 25-30 ℃, with an optimum of 28 ℃. Illumination had no significant effect on the linear growth of mycelium, conidial germination and appressorium formation. The pH values for the mycelial growth and conidial germination were 5.0-8.0, with an optimum of pH 6.0. The lethal temperature of conidia and mycelia explored further were 50 ℃/10 min. 

Abstract:In the summer of 2009,fruit rot of Hylocereus undatus occurred heavily in storehouses in Zhanjiang district of Guangdong Province.The pathogen causing the disease was identified as Bipolaris cactivora based on systematic analysis including isolation,pathogenicity test and morphological observation.To our best knowledgement,it is the first report of B.cactivora infecting H.undatus in China mainland.