Mazzola Mark, Andrews Preston K, Reganold John P, Lévesque C André
USDA-ARS, Tree Fruit Research Laboratory, Wenatchee, WA, 98801.
Department of Horticulture & Landscape Architecture, Washington State University, Pullman 99164.
Plant Dis. 2002 Jun;86(6):669-675. doi: 10.1094/PDIS.2002.86.6.669.
Studies were conducted to characterize the community of Pythium spp. associated with apple in Washington state. Seventeen different species were identified among the isolates of Pythium recovered from apple roots at six orchard sites. Commonly isolated species included P. intermedium, P. irregulare, P. heterothallicum, P. sylvaticum, and Pythium MM1 (aff. macrosporum), a previously undescribed species. The population of Pythium spp. at any given site typically was dominated by a single pathogenic species. Species composition of Pythium populations in adjacent conventional and organic blocks in two orchards did not differ; however, the relative recovery of Pythium spp. from apple roots was consistently lower in the organically managed systems. In greenhouse studies, the associations formed between apple seedlings and Pythium spp. ranged from pathogenic to growth-promoting. Precolonization of apple seedling roots with any one of three nonpathogenic isolates tested-isolate 584 of Pythium MM1, isolate 1-12 of Pythium MM3 (aff. oedochilum), and isolate 1-19 of Pythium MM5 (aff. vexans)-was found to provide biological control of root rot caused by P. sylvaticum and P. ultimum. Metalaxyl sensitivity varied among species of Pythium, with several nonpathogenic species exhibiting the highest levels of insensitivity to this fungicide.
开展了多项研究，以表征华盛顿州与苹果相关的腐霉菌群落。从六个果园地点的苹果根系中分离出的腐霉菌菌株中，鉴定出了17种不同的物种。常见的分离物种包括中间腐霉、不规则腐霉、异宗腐霉、林地腐霉以及腐霉菌MM1（近大孢腐霉），后者是一个此前未描述过的物种。在任何给定地点，腐霉菌种群通常由单一的致病物种主导。两个果园相邻的传统种植区和有机种植区中腐霉菌种群的物种组成没有差异；然而，在有机管理系统中，从苹果根系中分离出腐霉菌的相对回收率一直较低。在温室研究中，苹果幼苗与腐霉菌形成的关联从致病到促进生长不等。研究发现，用三种测试的非致病分离株中的任何一种对苹果幼苗根系进行预定殖——腐霉菌MM1的分离株584、腐霉菌MM3（近水生腐霉）的分离株1-12以及腐霉菌MM5（近缠绕腐霉）的分离株1-19——可对由林地腐霉和终极腐霉引起的根腐病起到生物防治作用。腐霉菌不同物种对甲霜灵的敏感性各不相同，几种非致病物种对这种杀菌剂表现出最高水平的不敏感性。
