Leaf spot caused by Leaf spot Fungi

The disease has been found in Australia, the United States, India, Japan, Mexico, the Philippines and other places. There are many kinds of orchids, such as orchid sheep, spider orchid, Cartland, orchid, Dendrobium, lily orchid, orchid, Oncidium, Papaenopsis, Phalaenopsis, orchid, orchid, vanilla, orchid and so on. The pathogen was identified as Phyllostictina pyriformis. In the early stage of infection, a single disease spot appeared on the leaf and pseudobulb, which was small and yellow. With the expansion of the disease spot, the spot was sunken, especially on the leaf, and the color changed from brown to dark brown, and the edge was raised. Red to purple-black, a single disease spot is round to oval, but when more than two disease spots are combined, irregular patches are formed. Most of the lesions on the pseudobulbs are oval and distributed longitudinally, and the average diameter of a single spot is about 0.6cm, but in many cases it will be slightly smaller or much larger. Finally, the brown or brown area of the disease spot appears slightly raised black spots, which is the conidium of the pathogen, which contains the conidia of the pathogen.

The control of the disease can be sprayed with 50% Benton 50% wettable powder, once every two weeks, a total of 3 times, the concentration is 10OO solution, and add wetting agent. You can also use thiram or chlorothalonil 2787, the method is to apply twice a month, the concentration is 8O0 solution. The removal and destruction of all susceptible parts helps to protect tissues that have not been infected. (Liu Zhongjian)