兰花炭疽病的发病规律及防治

兰花炭疽病菌在病叶组织内越冬,4月上、中旬初次侵染,分生孢子能再次侵染。病害发生期为4～11月,其中4～8月为老叶发病期,7～11月为新叶发病期。病害发生与温度、湿度、降雨量和雨日有关。病害流行的最适气温为25℃左右,相对湿度85％以上,雨量大、雨日长发病严重。病害程度与品种有关,春兰、寒兰、和秋兰均发病严重;台兰发病较轻。在病害发生期使用1％波尔多液及75％百菌清、50％稻瘟酞、25％培福朗、50％代森锰锌等1000倍液,有明显的防治效果,其防效达75％以上。

Disease Occurrence and Chemical Control of Orchid Anthracnose

The causal organism of orchid anthracnose. i. e. Colletotrichum orchidearum Allesch, could overwinter on the diseased leaves of orchid. The primary infection of the disease occurred during early or middle April. The conidia could infect plants once again. The disease happened from April to November, on the old leaf from April to August, on the young leaf from July to November. High rainfall, long rainy days, warm and moist conditions were favorable to the infection of the disease. Susceptiblity to the disease was quite different among species or varieties of orchid, and Cymbidium vire-seen L., C. kamran Makino and C. ensifolium (L.) Swartz were most susceptible. Good control results could be obtained by spraying with 1 per cent bordeaux mixture or 0.075 per cent chlorothalonil, 0.05 per cent rabcide and 0.05 per cent mancozeb, and effective percentage reached over 75 per cent.