Prevention and Control of Diseases and insect pests of White Orchid

White orchid leaves green, flowers as white as jade, fragrant Ruolan, lovable. However, it is often due to poor management, suffering from diseases and insect pests, causing yellow leaves and small flowers, affecting the viewing, which is a disappointment. The common diseases of white orchid are yellowing, anthrax, root rot; insect pests are shell insects, red spiders, aphids, spider moths and so on.

First, anthrax. Mainly occurred in the leaves, the initial performance of chlorosis, the emergence of small yellow spots, and then gradually expanded into a round or oval, several disease spots merged into irregular spots, the center of light brown, the edge of dark brown. When the disease spot occurs at the edge of the leaf, it is semicircular, making the leaf a little twisted. When the disease is serious, the whole leaf is scorched, blackened and shedding. The disease is a fungal disease and the pathogen overwinters in the host disease tissue. Excessive watering of potted plants and excessive humidity are easy to cause the disease. The disease usually begins in early June and is at its peak from July to August. The prevention and control methods are as follows: improve the watering method to inject water from the edge of the basin, not too much; combine pruning, cut off the diseased leaves, remove fallen leaves and destroy them, so as to reduce the source of the disease; in the spring and plum rain seasons, spray the same amount of Bordeaux solution 100 to 200 times every 10 to 15 days, 65% Dysen zinc 500 to 800 times, or 70% methyl topiramate 1000 times, three to four times in a row to inhibit the occurrence of the disease.

Second, root rot. It is a fungal disease. Excessive watering or waterlogging of white orchids can easily lead to root blackening and decay, poor growth of light ones, yellowing and shedding of leaves, and death of the whole plant. Prevention and control methods: efforts to improve soil drainage conditions is an important measure to prevent the disease. If you want to see dry and wet, pour thoroughly and pay attention to loosening the soil; on continuous rainy days, it is necessary to prevent rain and dump stagnant water in the basin in time; the bottom of the basin should be padded with more drainage materials such as broken tiles. When placed outdoors, it is best to use bricks to cushion the flowerpot to facilitate drainage; when the plant is infected during the growing period, the root soil can be irrigated with chemicals such as 65% generations of zinc, 50% generations of ammonium, or 50% carbendazim.

Third, chlorosis. Also known as chlorosis, is a physiological disease. The basin soil is partial to alkali, and at the same time, the water containing more saline-alkali components is used to irrigate the white orchid leaves in the slightly acidic soil, which will gradually change from green to yellowish white, and in serious cases, the local necrosis of the leaves will be brown. Immediately after the attack, spray 0.5% of ferrous sulfate solution on the leaves once a week, three to four times in a row, and apply alum fertilizer and water at the same time.

Fourth, insect pests. White orchids are sometimes harmed by shell insects and red spiders. The leaves of the damaged plants turn yellow and fall off one after another, affecting their growth and development. Usually, we should often check the back of the leaves and find that a small number of shell insects can be caught artificially. When you find a red spider, you can use a sanitary sprayer, fill it with water, add three to four drops of dichlorvos or dimethoate, spray and kill. If there is no sprayer, you can also use a small wood (bamboo) stick, stick a cotton ball at one end and dip it with dichlorvos, insert it into the basin for fumigation, and you can get a good control effect. Aphids occur between spring and summer, and the occurrence of aphids is the most serious from May to June, mainly harming new shoots in spring and summer. 40% dimethoate or 25% imidophos can be used.