Studies On The Pathology & Control Measures Of Cyclaman Leaf Spot Disease

It is the first time that the pathogens, biological characteristics, occurrence regularity and control measures of cyclamen leaf spot disease are studied systematiclally through this trialCyclaman leaf spot is the new leaf disease which was epidemic and reported in recent years. Its incidence rate was 20% to 30% generally, but can severely reach to 50%.The pathogenetic strains of cyclaman leaf spot was obtained by isolation and investigation. It was identified as Alternaria. alternata(Fr) keissler, according to its pathogenicity, biological characteristics, cultivation and shape.The biological test showed that the mycelia could grow and conidial could germinate at 10-45℃,and the optimal condition for the mycelia growth and spores formation is at 30℃,the suitable condition is at 25-30℃.Light could repress the formation of spores,but could accelerate the germination of spores The mycelia could grow and conidial could germinate when the value of pH is 4.0-9.0, and the optimal pH is 6.0-7.0.The mycelia can utilize the substances of carbon sources such as grapesugar,maltose.sucrose very well. More spores could be produced well on sucrose .The Nithogen sources such as potassiym nitrate and. Glycine could be highly benefited to their growth.The result of study on occurrence regularity showed: Pathogen overwintered with my celium and conidia on marigold refuse, which were the primary infection resources, secordly was from infected seeds. The occurences of the disease was obosely correlated with humidity, amount and kind of fertilizers and crop rotation. High humidity or more N was favorably for the disease epidemic, but right P and rotation could increase the variety resistance to the disease.According to studies on the control measures showed: seclecting and cultivating the disease-resistant varities of Cyclaman such as Latinia and Halios etc, seeds disinfect and fungicides sereening were experienced. The result indicated that Cyclaman leaf spot disease was effectively controlled with spraying "80% Dasheng wp500×", "72%Sukelin wp800×", "Duojunlin wp 400×", meanwhile, infecting with 0.1% KMnO4 for 30 min or soaking with 52oC water for 10 min could markedly reduce the amount of the fungi.Total to say, the integrated controlling measures of cyclamary leaf spot have been put forward by studying systematically the disease.These measures include selecting the disease and cultivating resistante varities of cyclaman, soaking the seeds, cleaning away marigold refuse in the field, strengthening croprotation and cultivation managements , applying fertilizers and properly spraying fungicides appropriately.