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.

Identification and biological characteristics of southern blight causing root rot on three medicine plants of Iridaceae in Dabie Mountains / 中国中药杂志

In order to identify the species and biological characteristics of the pathogen of southern blight from three kinds of Chinese medicine of Iridaceae(Belamcanda chinensis, Iris tectorum and I. japonica) in Dabie Mountains, the isolation, identification, pathogenicity and biological characteristics of the pathogens were studied according to Koch's postulates. In addition, 9 chemical fungicides, 3 botanical fungicides and 5 microbial fungicides were used to evaluate their inhibition to the isolates in vitro. The results showed that all the strains(SG-Q, YW-Q, and HDH-Q) isolated and purified from the diseased plants of B. chinensis, I. tectorum and I. japonica, respectively, were identified as Sclerotium rolfsii through morphological observation and sequence aligement of 18 S rDNA, rDNA-ITS and TEF. Field observations showed that the intensity of the disease incidence of three Iridaceae plants was B. chinensis>I. japonica> I. tectorum, and the pathogenicity of the strains was SG-Q>YW-Q>HDH-Q. For biological characteristics, SG-Q strain was suitable for growth under the 12 h light/12 h dark cycle, with the optimal growth temperature of 30 ℃ and pH of 5. Among the 9 tested chemical fungicides, 29% lime sulphure and 10% flusilazole had stronger inhibitory effect on mycelia growth of SG-Q. For 3 botanical fungicides, 1% osthol, 20% eugenol and 0.5% berberine could effectively inhibt the mycelial growth of SG-Q and cause the morphological variation of the pathogen. For 5 microbial fungicides, Trichoderma harzianum and Bacillus subtilis had better inhibition on the mycelium growth of SG-Q.

Effect of N, P, and K fertilizers on sclerotial formation and germination of southern blight of Coptis chinensis / 中草药

Objective: To study the effect of nitrogen (N), phosphorus (P), and potassium (K) fertilizers on the sclerotial formation and germination of southern blight of Coptis chinensis so as to provide scientific basis for its integrated pest management (IPM). Methods: Preparation of different concentrations of N, P and K was added into soil and the mycelium and sclerotia were put on the soil, and then the effect of the fertilizers on the sclerotial formation and germination was observed. Results: The treatment of CO(NH 2)2 and NH4HCO3 had significant inhibition on sclerotial formation and germination. The treatment of NaH 2PO4, KCl, and KNO3 showed the facilitation in various degrees to promote the sclerotial formation and germination. The treatment of KH2PO4 had no significant effect on sclerotial germination, but it had significant inhibitory activity to sclerotial formation. Conclusion: In the production, the partial N, while less K and P fertilizers should be put to control the sclerotial formation and germination of southern blight of C. chinensis.

Occurrence and spreading dynamics and control methods of Southern blight in Houttuynia cordata / 中草药

Objective To study the occurrence and spreading dynamics of Southern blight Houttuynia cordata and search for the control method so as to provide scientific basis for its integrated pets management (IPM). Methods The field investigation and the combined methods in both field trial and laboratory test were carried out for the research. Results After treated by Carbendaxim, the morbidity of Southern blight in H. cordata was the lowest and the yield of H. cordata reached to the highest level among all treatment groups. The PDA test revealed that Trichoderma huzirum had stronger antagonism to Southem blight in H. cordata than common fungicides. The best concentration of T. huzirum used in the soil treatment was 20 g/m2, which had a preventive effect against Southern blight up to 60.28%. Conclusion The Southern blight of H. cordata could be well suppressed while both Carbendaxim and T. huzirum are used to treat the seeds and soil, respectively.