Identification,biological characteristics and fungicide screening of pathogen of southern blight in Cynanchum stauntonii / 中国中药杂志

During the high-temperature and rainy season from June to October in 2017-2019,serious southern blight broke out in the Cynanchum stauntonii planting area in Tuanfeng county,Hubei province,which had a great impact on the yield and quality of medicinal materials. In this study,the pathogen of C. stauntonii was isolated,purified,and identified,and the pathogenicity was tested according to Koch's postulates. Meanwhile,the biological characteristics of the pathogen were analyzed. On this basis,the effective fungicides were screened in laboratory. Finally,the pathogen( BQ-1) was identified as Athelia rolfsii( Deuteromycotina,Basidiomycota,anamorph: Sclerotium rolfsii). The optimum growth conditions for BQ-1 were 25-30 ℃,p H 5-8,and alternating light and dark.The effective chemical fungicides were lime-sulphur-synthelic-solution( LSSS) and flusilazole,and the effective botanical fungicide was osthole. BQ-1 was highly homologous to the pathogen HS-1 of peanut southern blight,with the similarity of 18 S r DNA and TEF sequences at 99. 09%. The southern blight in C. stauntonii might be resulted from that in peanut. In the production of C. stauntonii,the following measures should be taken: avoiding rotation or neighboring with peanut,draining water from June to October to reduce humidity,and reasonably applying fungicides.

Uso de Trichoderma harzianum e condicionador orgânico de solo para controle da podridão por Sclerotium rolfsii em alho / Use of Trichoderma harzianum and peat based soil amendment to control garlic rot caused by Sclerotium rolfsii

Sclerotium rolfsii é um agressivo patógeno de várias culturas, entre elas o alho (Allium sativum). Uma alternativa de controle da doença é o uso de agentes biológicos. Neste estudo, foi avaliada a eficiência de Trichoderma harzianum comercial em relação a fungicidas (procimidona e tiofanato metílico) por teste de germinação de esclerócios em solo em laboratório e teste in vivo em casa de vegetação. Os testes foram conduzidos em delineamento inteiramente casualizado e em blocos ao acaso, no laboratório e em casa de vegetação, respectivamente. Para avaliar o efeito a germinação de esclerócios, foram aplicados: T. harzianum, condicionador de solo + T. harzianum, condicionador de solo, procimidona e testemunha (água esterilizada). Nos experimentos in vivo foram aplicados seguintes tratamentos: T. harzianum, condicionador de solo + T. harzianum, condicionador de solo, procimidona, tifanato metílico e testemunha (água esterilizada), e foram avaliados: % de plantas infectadas, massa seca de raízes, massa seca da parte aérea, número de esclerócios capturados. Trichoderma harzianum e condicionante de solo + T. harzianum reduziram a % de germinação de esclerócios. No teste in vivo foi observado: (a) menor % de plantas infectadas, (b) aumento de massa seca de raiz e parte aérea em relação à testemunha com patógeno, e; (c) menor número de esclerócios capturados nos tratamentos com T. harzianum. Os tratamentos com fungicidas e somente com condicionador de solo não reduziram o número de plantas infectadas e esclerócios capturados.

Sclerotium rolfsii is an aggressive pathogen of various cultures, including garlic (Allium sativum). Biological control is one of the alternatives to this disease. This study evaluated effectiveness of commercial Trichoderma harzianum product in relation to fungicides (procimidone and thiophanate methyl) with sclerotia germination tests (soil in plastic boxes) and in vivo tests. Experiments were conducted in laboratory and greenhouse in a completely randomized and randomized block design, respectively. To evaluate the effect of products on germination of sclerotia were applied the following treatments: Trichoderma harzianum, peat based product + T. harzianum, peat based product, procimidone and control (sterile water). For the in vivo tests were applied: T. harzianum, peat + T. harzianum, peat, procimidone, tiophanate methyl and control (sterile water). For the in vivo tests were evaluated: % infected plants, roots dry weight, shoots dry weight, number of sclerotia captured per kg soil. Peat + T. harzianum and T. harzianum significantly reduced the sclerotial germination percentage. In vivo tests treatments with T. harzianum induce the following results: (a) less % of infected plants, (b) increase in dry roots weight and dry shoot weight compared to control with the pathogen, and; (c) fewer number of captured sclerotia. The treatments with fungicides and peat did not reduce the % of infected plants and sclerotia captured.