Matheron M E, Porchas M, Bigelow D M
Yuma Agricultural Center, The University of Arizona, Yuma 85364.
Department of Plant Sciences, Division of Plant Pathology and Microbiology, The University of Arizona, Tucson 85721.
Plant Dis. 2006 May;90(5):554-558. doi: 10.1094/PD-90-0554.
Brown heartwood rot, which often is found in branches within lemon groves in southwestern Arizona, is caused by two basidiomycete fungi, Antrodia sinuosa and Coniophora eremophila. Another fungus, a species of Nodulisporium, has been recovered from small, dying lemon tree branches with an internal white wood rot. Studies were conducted from 1999 through 2002 to compare the extent of wood decay caused by these fungi (i) on lemon tree branches at different times of the year, (ii) on different types of citrus, (iii) on some desert woody perennial plants, and (iv) on lemon tree branches treated with selected fungicides. The mean length of wood decay columns recorded in lemon tree branches inoculated with A. sinuosa, C. eremophila, and the Nodulisporium sp. during the time periods of November to January, February to April, May to July, and August to October was 2.9, 4.7, 13.3, and 15.2 cm, respectively. There was a significant linear correlation between the length of wood decay columns and air temperature for all three pathogens. The mean length of wood decay columns for all time periods in branches inoculated with A. sinuosa, C. eremophila, and the Nodulisporium sp. was 11.8, 5.8, and 9.6 cm, respectively. In two trials, wood decay columns were significantly greater on Lisbon lemon tree branches inoculated with A. sinuosa compared with those on Marsh grapefruit and Valencia orange trees inoculated with the same pathogen. Wood decay in the presence of the Nodulisporium sp. was greater on branches of lemon compared with grapefruit trees in two trials and on lemon compared with orange trees in one of two trials. With the exception of C. eremophila on creosote bush, each of the three wood rot pathogens caused some wood decay in branches of velvet mesquite, salt cedar, Mexican palo verde, and creosote bush, four common desert perennials found in southwestern Arizona. Compared with nontreated but inoculated lemon trees, the length of wood decay columns in branches inoculated with A. sinuosa, C. eremophila, and the Nodulisporium sp. in the presence of propiconazole was reduced by 79, 94, and 92%, respectively, and, in the presence of azoxystrobin, was suppressed by 71, 80, and 89%, respectively. Current management guidelines focus on minimizing branch fractures and other nonpruning wounds in conjunction with early detection and removal of infected branches before the onset of the increased wood decay development period extending from May to October.
褐心材腐朽常见于亚利桑那州西南部柠檬果园的树枝上，由两种担子菌真菌引起，即弯曲拟盘多毛孢（Antrodia sinuosa）和荒漠卧孔菌（Coniophora eremophila）。另一种真菌，一种瘤座孢属（Nodulisporium）的菌种，已从内部呈现白色木材腐朽的濒死小柠檬树枝中分离得到。在1999年至2002年期间开展了多项研究，以比较这些真菌导致的木材腐朽程度：（i）在一年中不同时间对柠檬树枝条造成的影响；（ii）对不同种类柑橘造成的影响；（iii）对一些沙漠木本多年生植物造成的影响；（iv）对用选定杀菌剂处理过的柠檬树枝条造成的影响。在11月至1月、2月至4月、5月至7月以及8月至10月期间，接种弯曲拟盘多毛孢、荒漠卧孔菌和瘤座孢属菌种的柠檬树枝条中，记录到的木材腐朽柱平均长度分别为2.9厘米、4.7厘米、13.3厘米和15.2厘米。对于所有这三种病原菌，木材腐朽柱的长度与气温之间均存在显著的线性相关性。接种弯曲拟盘多毛孢、荒漠卧孔菌和瘤座孢属菌种的树枝在所有时间段内木材腐朽柱的平均长度分别为11.8厘米、5.8厘米和9.6厘米。在两项试验中，接种弯曲拟盘多毛孢的里斯本柠檬树枝条上的木材腐朽柱显著长于接种相同病原菌的马叙葡萄柚和伏令夏橙树上的木材腐朽柱。在两项试验中的一项试验里，瘤座孢属菌种存在时，柠檬树枝条上的木材腐朽程度大于葡萄柚树枝条；在两项试验中的另一项试验里，柠檬树枝条上的木材腐朽程度大于橙子树枝条。除了荒漠卧孔菌对石炭酸灌木造成的影响外，这三种木材腐朽病原菌均对绒毛豆科灌木、盐肤木、墨西哥牧豆树和石炭酸灌木（在亚利桑那州西南部发现的四种常见沙漠多年生植物）的树枝造成了一定程度的木材腐朽。与未处理但接种了真菌的柠檬树相比，在丙环唑存在的情况下，接种弯曲拟盘多毛孢、荒漠卧孔菌和瘤座孢属菌种的树枝中木材腐朽柱的长度分别减少了79%、94%和92%；在嘧菌酯存在的情况下，木材腐朽柱的长度分别被抑制了71%、80%和89%。当前的管理指南侧重于尽量减少树枝折断和其他非修剪伤口，并结合早期检测以及在5月至10月木材腐朽加剧发展期开始之前清除受感染的树枝。
