Mondal S N, Vicent A, Reis R F, Timmer L W
University of Florida, Department of Plant Pathology, Citrus Research and Education Center, Lake Alfred 33850.
Instituto Agroforestal Mediterráneo, Universidad Politécnica de Valencia, Valencia-46022, Spain.
Plant Dis. 2007 Apr;91(4):387-392. doi: 10.1094/PDIS-91-4-0387.
Melanose, caused by Diaporthe citri, produces reddish brown lesions on the fruit, leaves, and twigs of citrus trees, and greatly reduces the marketability of fresh fruit. Most of the inoculum is produced in pycnidia on dead twigs in the tree canopy, which exude large numbers of conidia in slimy masses. In this study, detached twigs inoculated with conidia were readily colonized and produced large numbers of pycnidia within 30 to 40 days when they were soaked 3 to 4 h on alternate days. Conidial production was measured by wetting twigs in a rain tower periodically and collecting the conidia in the runoff water. Production began after 80 days and continued for nearly 300 days. In other experiments, production of mature pycnidia on detached twigs was greatest at 94 to 100% relative humidity (RH) and at 28°C. Low RH and temperature, however, favored survival of conidia in exuded masses on twigs. In the field, colonization of detached twigs by D. citri was high in rainy season, moderate in spring and early fall, and minimal in late fall and winter. Twig colonization was positively related to the number of rain days and average temperature, but not to total rainfall. In another experiment, inoculated twigs placed in the tree canopy developed pycnidia and then produced conidial masses for about 200 days. D. citri is a serious pathogen, but a weak parasite, that survives primarily by colonization and reproduction on dead twigs.
由柑桔间座壳菌引起的黑色素病会在柑橘树的果实、叶片和嫩枝上产生红棕色病斑，大大降低新鲜水果的市场价值。大部分接种体在树冠上枯死嫩枝的分生孢子器中产生，分生孢子器会分泌出大量粘稠团块的分生孢子。在本研究中，接种分生孢子的离体嫩枝在每隔一天浸泡3至4小时的情况下，很容易被定殖，并在30至40天内产生大量分生孢子器。通过定期在降雨塔中淋湿嫩枝并收集径流水中的分生孢子来测量分生孢子的产生量。分生孢子产生在80天后开始，并持续近300天。在其他实验中，离体嫩枝上成熟分生孢子器的产生在相对湿度（RH）为94%至100%且温度为28°C时最为旺盛。然而，低相对湿度和温度有利于分生孢子在嫩枝上分泌的团块中存活。在田间，柑桔间座壳菌对离体嫩枝的定殖在雨季较高，在春季和初秋适中，而在深秋和冬季最少。嫩枝定殖与降雨天数和平均温度呈正相关，但与总降雨量无关。在另一项实验中，放置在树冠中的接种嫩枝形成了分生孢子器，然后产生分生孢子团约200天。柑桔间座壳菌是一种严重的病原体，但却是一种弱寄生菌，主要通过在枯死嫩枝上定殖和繁殖来存活。
