Oncidium and its related genus Orchid Leaf spot

① damage: this Cercospora fungus can infect some species and hybrids of Oncidium and related orchids, causing little harm to plants and occasionally serious. In addition to Oncidium, other related genus hosts that can be infected are Comparettia, Mitonia, Rodrettia,Rodricidium and Rodriguezia.

② symptoms: the symptoms that initially appear on the back of the leaf are sunken light reddish purple spot, slightly raised in the center, is light brown, a single spot diameter is usually smaller than 1mm, with the maturity of the spot, the whole spot will be sunken, if more than 2 spots combine, it will eventually become a sunken reddish purple spot; up to several millimeters in diameter, the corresponding part of the front of the leaf will become yellowish green.

③ prevention and treatment: use 50% benzoate wettable powder 1OOO double solution and add a small amount of wetting agent spray for 3 times, once every 2 weeks. After that, spray once a month if necessary.

Liu Zhongjian