黑核桃腐烂病菌主要生物学特性及室内药剂筛选

A Preliminary Report of Main Biological Characteristics of Black Walnut Rot and Screening of Indoor Fungicides

【目的】研究黑核桃腐烂病菌(Cytospora chrysosperma)的生物学特性,以病原菌为靶标进行室内杀菌剂毒力测定实验,为田间防治药剂的筛选提供备选药剂。【方法】采用菌丝生长速率法,分别测定病原菌在不同碳源、温度、pH值和光照条件下的生长速率,研究病原菌生物学特性。测定病原菌的室内药剂毒力。【结果】病原菌在供试的8种不同碳源培养基均可生长,在PDA、PSA、PCA和胡萝卜培养基培养基上长势好于其它4种不同碳源的培养基,其中病原菌在PDA上生长最好,其次为PSA、PCA和胡萝卜培养;病原菌在5~35℃均能生长,其中最适温度在(25±1)℃;病原菌在pH值3~10均能生长,其中在pH值5.0左右的条件下生长最为适宜;病原菌在24h光照,12h光暗交替和24h黑暗三种光照条件下菌丝生长差异不显著,其中24h光照条件下菌丝生长相对较快,而在其它2种光照条件下菌丝生长相对缓慢;12种供试药剂对黑核桃腐烂病菌的毒力大小存在明显的差异,其中,10%苯醚甲环唑毒力最大,EC50值为0.001mg/L,其次为16%苯甲中生,EC50值为0.017mg/L,而47%春雷王铜毒力最小,EC50值为2481.10mg/L。【结论】在供试8种培养基中,最适合核桃腐烂病菌生长的培养基为PDA,最适生长温度在25℃左右,最适pH值为5,最适光照条件为24h光照。供试的12种杀菌剂对菌丝生长均具有一定的抑制作用,其中苯醚甲环唑的抑菌作用最强,其次为苯甲中生和多锰锌,3种药剂可作为田间药剂筛选试验的备选。

【Objective】 To preliminarily clarify the biological characteristics of the black walnut rot (Cytospora chrysosperma) and carry out the toxicity test of the fungicides to the pathogen in the laboratory in the hope of providing alternative pesticides for the screening of field control agents.【Methods】 The mycelial growth rate method was used to determine the growth rate of pathogen under different carbon sources, different temperatures, different pH values and different light conditions, thereby, to preliminarily clarify the biological characteristics of pathogen. The toxicity test of the fungicides to pathogen was carried out to provide alternative pesticides for field control.【Results】 Pathogens could grow on 8 kinds of different carbon source media, but they grew better on PDA, PSA, PCA and carrot medium than on other 4 different carbon source media. Pathogens grew best on PDA, followed by PSA, PCA and carrot culture. Pathogens could grow at 5-35℃, and the optimum temperature was (25±1)℃. Pathogens could grow in the range of pH 3-10, but the most suitable condition was pH value about 5. There was no significant difference in mycelial growth of pathogen under 24 h light, 12 h alternation of light and dark and 24 h darkness;Among them,, the mycelial growth of pathogen was relatively fast under 24 h light, but relatively slow under the other two light conditions. There were significant differences in toxicity of 12 selected agents to black walnut rot pathogen. Among them, 10% difenoconazole was the most virulent, whose EC 50 value was 0.001 mg/L, followed by 16% benzol, whose EC 50 value was 0.017 mg/L, while 47% kasugamycin-copper acetate was the least virulent, whose EC 50 value was 2,481.10 mg/L.【Conclusion】 PDA was the most suitable medium for the growth of Cytospora chrysosperma among the selected 8 kinds of media, The optimum growth temperature was (25±1)℃, the optimum pH value was 5, and the optimum illumination condition was 24 hours. The selected 12 kinds of fungicides have certain inhibitory effects on mycelial growth, among them, the difenoconazole had the strongest inhibitory effect, followed by benzoyl mesophyll and polymanganese zinc. The 3 kinds of fungicides could be used as alternatives for field pesticides screening experiments.