What are the methods for preventing and treating orchid leaf diseases?

Orchidleaves may wither and die for unknown reasons. Sometimes the leaves develop speckled black spots, and some gradually dry out from the leaf tip.
　　
GrowingorchidsThe environment, temperature, sunlight, light, and whether conditions are suitable all affect theorchid'sgrowth. Generally, black spots on the leaves are caused by fungal or bacterial infection. If the leaf tip gradually dries out, it indicates that fertilizer residue near the roots is too high, affecting water absorption, and the fertilizer concentration should be reduced.
　　
Edible alkali can treat orchid white silk disease
　　
Last year, one pot of Qiusu developed white silk disease. Because the orchid pot was tilted, by the time it was discovered the mycelium had already covered the pot surface. The current-year growths, about 15 cm tall at the time, had completely rotted at the base and came up with a single pull; 100% of the parent pseudobulbs had disease spots penetrating deep into the bulb flesh; more than 90% of the grandparent pseudobulbs had disease spots of varying degrees. Healthy latent buds were hard to find.
　　
Conventionally, this pot of Qiusu together with the potting soil should be thoroughly destroyed. But after washingthe orchid plantsclean, they were divided into three groups according to the severity of the disease. The first group consisted of a few old plants that had fortunately escaped infection; the second group had pseudobulbs with disease spots of varying sizes on the cortical layer; the third group was slated for disposal, with disease spots already penetrating deep into the bulb flesh. Inspired by the fact that lime can prevent and treat white silk disease, I chose edible alkali, the additive used in making steamed buns, and for groups one and two, soaked the leaves in 1.5% alkaline water for one minute, then soaked the parts below the base for 20 minutes, then rinsed with tap water, dried in the shade for 12 hours, and potted them separately. When handling the third group, I found one parent plant whose pseudobulb was especially large, as thick as a thumb, with a light brown disease spot the size of a broad bean near the soil surface. I picked out the rotten flesh with my fingernail until part of the healthy flesh was also removed. At this point only 2/3 of the pseudobulb remained, with two leaves and two broken roots left, and it was also treated by the above method and planted in a separate pot. Seven to ten days after planting, groups one and two successively sent out new shoots; the current-year growths were weaker, and by last spring they had grown into strong plants. The remnant plant of the third group, with only 2/3 of the bulb flesh left, unexpectedly also grew a new shoot, but the overwintering growth that grew to about one inch long also sent out a new plant, with slightly weaker growth, and now the shoot is more than 20 cm tall.