| 【Objective】Powdery mildew is one of the most serious fungal diseases in both field and greenhouse production of many plants,and its infection can cause serious yield loss.Ampelomyces quisqualis is an aggressive parasite many powdery mildew fungi belonging to Erysiphales,and it has been commercialised as biofungicide.This study aims to analyze the prevalence situation and the biocontrol potential on powdery mildew of A.quisqualis in municipal environment of Shihezi.【Methods】We made a detailed analysis at the infection frequency and the infection index of Erysiphales mycelium had been parasitized by Ampelomyces and isolated the mycoparasite fungi on three types of flowers used water agar filter picked pycnidia.Identification of mycoparasite species are described and illustrated based on morphological characteristics and phylogenetic analysis of ITS-r DNA sequences and strains were analysed for their parasitism,reproduction ability and disease control effect through internal primary screens and field trials.【Results】The high participation of the Ampelomyces was noted in the powdery mildew of the study.The presence of Ampelomyces was detected on 17 out of 18 plants samples.The higher number of the samples with mycoparasites was noted in the case of compositae(the incidence of parasitism by A.quisqualis 40.92).The highest number of the samples with mycoparasites was noted in the case of Golovinomyces(43.59 of the samples).The isolation rate of the water agar filter picking pycnidia(90 %)method was significantly(P<0.01)higher than that of direct picking pycnidia with needle(30%).The Ampelomyces were all able to grow on six medium,Czapek,PDA,PSA and their added malt extracts respectively,with isolation rates above 90.0%.But there were significant differences in the growth rate on different medium.The growth rate of the colonies was significantly(P<0.05)enhanced due to the addition of malt extract.That the pycnidia of mycoparasite were separate,globose,or elongated to pyriform,unilocular,of pale brown angular textured,the size40.66～82.92×34.65～63.05 μm.Conidia are unicellular,hyaline,mostly guttulate conidia which are ovoid,clavate,cylindrical,or curved with a size of 3.88～5.67×2.19～2.75 μm,spore germination produces tube at one or both end.The ITS sequence of the nuclear r DNA gene of the 15 tested isolates had 94%-100% identity to those of Ampelomyces quisqualis.Hereby,the mycoparasite fungus was identified as A.quisqualis.84 strains were isolated and 12 test strains were selected by internal primary screens,the 12 strains were parasitism to the powdery mildew of Aster novibelgii in the greenhouse,however,there were significant differences in the potentiality of mycoparasitism and disease control among the strains.High infection frequency of strains are generally associated with high infection index;As-81 and Rh-60 had the best control effect with 46.62% and 46.15%,respectively.The test strains in its hyperparasitic effectiveness and control efficacy of powdery mildew on Aster novibelgii in the field that the time to parasitise colonisation was significantly different between strains,with mycoparasitation observed as early as 7 days after injection for Rh-60,Rx-106 and Rx-11.Strain As-81 had better control of Aster novibelgii powdery mildew,followed by Rh-60,with maximum control efficiency of 79.57% and 45.58%.The both strains can attack the ascomata of Uncinula necator,with immature ascomata predominant,【Conculusion】The strains As-81 and Rh-60 can effectively control powdery mildew of Aster novibelgii in the field as well as infestation of grape powdery mildew ascomata,effectively reduce the multiplication and expansion of powdery mildew fungus,thus exerting its purpose of effective powdery mildew control,and can be used as good biological control material for powdery mildew. |
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