Agostini J P, Peres N A, Mackenzie S J, Adaskaveg J E, Timmer L W
Instituto Nacional de Técnologia Agropecúaria, Montecarlo, Misiones, Argentina.
University of Florida, Gulf Coast Research and Education Center, Wimauma, FL 33598.
Plant Dis. 2006 Nov;90(11):1419-1424. doi: 10.1094/PD-90-1419.
Citrus black spot (CBS) is caused by Guignardia citricarpa, which incites lesions on citrus fruit and can induce fruit drop. Quiescent infections occur during the spring and summer, and symptoms appear at fruit maturity or after harvest. Thus, fruit from citrus areas affected by CBS represent a risk for introduction of this pathogen into new areas. The effects of preventive field fungicide programs, postharvest fungicide drenches, packinghouse fungicide applications, and storage temperatures on postharvest symptom development and viability of G. citricarpa in lesions were evaluated in five experiments on Murcott tangor, Valencia oranges, and lemons. Preventive field treatments and fruit storage at 8°C consistently reduced postharvest CBS development, whereas a postharvest fungicide drench or packinghouse treatment with fungicides had no effect on postharvest symptom development. In a separate experiment, postharvest appearance of symptoms was related to the percentage of fruit with symptoms at harvest. The preventive field fungicide program also consistently reduced the percentage of isolation of G. citricarpa from affected fruit, whereas storage temperature and packinghouse fungicide treatment gave variable results. The viability of the fungus declined with storage time of fruit after harvest, but G. citricarpa could still be readily isolated regardless of treatment. In another experiment, the viability of the fungus in detached fruit or peel was minimally affected by temperature or moisture during storage. The frequency of successful isolation declined with time, but G. citricarpa was still recovered frequently from symptomatic tissue at later times. The most effective means to reduce postharvest development of symptoms is through preventive application of fungicides during the fruit growing season and storage of harvested fruit at cold temperatures. None of the measures evaluated substantially reduced viability of G. citricarpa, and the pathogen would likely be introduced on symptomatic fruit from citrus areas with CBS.
柑橘黑点病（CBS）由柑橘球座菌引起，该病菌会在柑橘果实上引发病斑，并可能导致落果。潜伏感染在春季和夏季发生，症状在果实成熟时或收获后出现。因此，受CBS影响的柑橘产区的果实存在将这种病原菌引入新区域的风险。在针对默科特橘橙、伏令夏橙和柠檬开展的五项试验中，评估了预防性田间杀菌剂方案、采后杀菌剂灌根处理、包装厂杀菌剂处理以及储存温度对采后症状发展和病斑中柑橘球座菌活力的影响。预防性田间处理和8°C的果实储存持续降低了采后CBS的发展，而采后杀菌剂灌根处理或包装厂杀菌剂处理对采后症状发展没有影响。在另一项试验中，采后症状的出现与收获时带症状果实的百分比有关。预防性田间杀菌剂方案也持续降低了从受影响果实中分离出柑橘球座菌的百分比，而储存温度和包装厂杀菌剂处理的结果则各不相同。收获后果实储存时间延长，病菌活力下降，但无论处理方式如何，仍能很容易地分离出柑橘球座菌。在另一项试验中，储存期间温度或湿度对离体果实或果皮中病菌活力的影响极小。成功分离的频率随时间下降，但在后期仍能经常从有症状的组织中分离出柑橘球座菌。减少采后症状发展的最有效方法是在果实生长季节预防性施用杀菌剂，并将收获的果实冷藏。所评估的措施均未大幅降低柑橘球座菌的活力，该病原菌很可能会通过来自有CBS的柑橘产区的有症状果实传播。
