Why black spot is difficult to treat

Black spot, namely brown spot and anthrax, is caused by a pathogen infection. At first, the leaves appeared brown spots and gradually expanded into oval or semicircular slightly sunken wheel-shaped spots. Then, the disease spot dries up and spreads from Baozi to other leaves.

Although black spot does not do much harm and rarely dies, it will burn bluegrass and lose its ornamental value. Why black spot is difficult to treat. The reasons are as follows: first, once the pathogen of black spot meets a suitable climate or environment, it can occur at any time, even in winter, the greenhouse still spreads and grows; second, holding a kind of reproductive cell, leaving the mother, it can form a new individual, it spreads by spreading, it does not need plant materials, insects, fertilizer, water, tools and other media, and it is invisible, so it is very difficult to prevent micro-disease. Third, at the beginning of the disease, the spots are very fine, mostly on the back of the leaves, are more hidden, and are not easy to be found. once they expand into black spots, it is too late; fourth, those who are involved in the orchid are often treated according to the drug instructions, and they do not know that the application objects are different and their methods are different, so it is difficult to see the effect.

There are many drugs for the prevention and treatment of black spot, most of which are used in crops. Crops are different from flowers, some of them are for consumption, and pesticide residues are strictly regulated in the country, which are not allowed to exceed the standard. For example, methyl topiramate made in Japan, the manual warns: "use up to 2 times per season on wheat crops, 20 days before harvest, and up to 3 times per season on rice crops, 30 days before harvest." According to this convention, wheat should be applied at most once a month and rice once a month at most. It is impossible to think of black spot at such a long interval. However, wheat and rice are not for viewing, and what does it matter if you get a mild black spot as long as it does not affect the yield? It is not the same for orchids, even if you get a mild black spot, it also affects the ornamental, but it doesn't matter if the pesticide residue exceeds the standard. In order to control orchid black spot with methyl topiramate made in Japan, the interval time should be shortened, and it would be better to spray once a week.

Huakang No. 2, produced by Chengdu Huayi Science and Technology Development Company, is a special drug specially developed for the prevention and control of flower diseases. the method of use is very different from that of methyl topiramate made in Japan. "each packet is mixed with 1 kg of water. Spray evenly in the morning and evening every three or four days (2 kg of preventive dosage)." If it is used in crops according to this routine, the pesticide residues will certainly exceed the standard, but when used in orchids, black spot can be effectively controlled.

Huakang No. 2 is used in addition to orchids, there are other flowers and seedlings, orchids also have open-air orchid farms, most of these plants grow in the natural environment where black spot disease is very easy to be infected, and Huakang No. 2 is applied for a short time, probably related to this factor. If you use a closed environment to raise orchids, foreign black spot disease is not easy to enter, preventive medication can appropriately prolong the interval. If you want to get the right answer, you have to find it in practice. (Zhejiang Laotie)