不同地区橡胶树红根病菌的生物学特性及室内毒力测定

橡胶树红根病是我国分布最广、危害最重的橡胶树根部病害。为明确我国海南和云南地区橡胶红根病菌的生物学特性及对杀菌剂的敏感性,采用十字交叉法研究了不同培养条件对病菌菌丝生长的影响,并测定了10种不同杀菌剂对病菌的抑制作用。结果表明,病原菌在玉米+橡胶根的培养基上生长最快,对温度、pH等适应范围广,温度在13~31 ℃,pH在3~10均能生长,最适生长温度为28 ℃,多数菌株最佳pH为7~9,且能利用多种碳氮源;不同的碳源中,果糖、半乳糖、麦芽糖、葡萄糖和甘露糖较适合该菌的生长;在供试氮源中,菌丝在酪氨酸、牛肉浸膏的基础培养基上生长最快,在色氨酸和尿素的基础培养基上生长最慢;光照对病菌有抑制作用,黑暗有利于菌丝生长;菌丝的致死温度为47 ℃,10 min。不同地区的病原菌株间药剂敏感性存在一定差异,戊唑醇抑菌效果最好,其EC₅₀为0.0312 μg/mL,其次为嘧菌酯、十三吗啉、咪鲜胺和腈菌唑,EC₅₀分别为0.5581、0.6759、1.3763和1.5603 μg/mL。

Biological Characteristics and Toxicity Test of Pathogen Strains Causing Rubber Red Root Rot from Different Regions

Red root disease of the rubber tree, which occurred widely, not only causes severe damage to rubber tree production, but also becomes one of the major obstacles to the sustainable development of the rubber tree industry in China. To clarify the biological characteristics and sensitivity to different fungicides, the mycelia growth of Ganoderma pseudoferreum was determined using the crossing method, and the inhibitory activities of 10 fungicides on G. pseudoferreum were also studied. The results showed that the mycelia of the pathogen grew better on the medium CMA with rubber root. They could grow at temperature of 13 to 31 ℃, best at 28 ℃. They grew well at pH varied from 3 to 10, best at 7–9. They could utilize many substances as carbon and nitrogen sources. Among carbon sources tested, fructose, galactose, maltose, glucose and mannose were found to be the best ones for the growth of G. pseudoferreum. Tyrosine and beef extract were the most suitable nitrogen sources while tryptophan and ureal were the worst. Darkness was good for mycelial growth while light had an inhibitory action. The lethal temperature for the mycelium was 47 ℃ for 10 min. The sensitivity of the isolates sourced from different regions to fungicides was different from each other. Tebuconazole was the most effective fungicide against the pathogen with an EC₅₀ of 0.0312 μg/mL, followed by azoxystrobin, tridemorph, prochloraz and mycolbutanil with an EC₅₀ of 0.5581, 0.6759, 1.3763 and 1.5603 μg/mL respectively.