When is the right time to prevent and control anthracnose in Cymbidium sinense?

Anthracnose isCymbidium sinensean important disease. Many books always say prevention is more important than cure, and I agree with this point, but the books always rigidly say to spray once every 7~10 days. This statement is very general. In fact, the onset time of anthracnose follows a very regular pattern. Blind spraying is just a waste. As long as you pay attention to mastering the prevention and control timing, you can save a lot of costs. By observing the location where diseased seedlings develop symptoms, you can infer the time of infection. Under normal circumstances,Cymbidium sinensethe locations infected by anthracnose are overwhelmingly in the upper half of the leaf, while the lower half is rarely affected. The upper half grows during the plum rain season from spring to early summer when temperatures are not very high, and the lower half generally grows in the hot, humid summer to early autumn. The onset time is generally in the relatively dry period of one month from late September to mid-October. Last year we did an experiment like this: no spraying in spring or summer, and starting spraying for prevention and control in late August. The result showed that spraying for prevention and control in late August was already too late, and the lesions could not be controlled at all. This year we switched to regular spraying from mid-April to mid-July, and paid no attention after mid-month. We found that there was almost no disease, which overturns the theory stated in many books that high temperature and high humidity cause severe disease. It should be said this way: the onset of anthracnose follows a certain pattern, and spraying at the right time is the foundation of prevention and control. At the time, this view was discovered by a local orchid grower. He learned this disease onset pattern from the prevention and control of banana anthracnose. The onset time of banana is very similar to that oforchids. The experimental results, although the data are still insufficient, have already been confirmed over two years, so it can be said to have a certain feasibility. Everyone may as well share more views. (Wei Chang)