Causes and solutions of yellowing, blackening and rotting root death of orchid leaves in summer

In a year, orchids are the most difficult to raise in summer. all kinds of diseases and insect pests occur frequently. Orchids are either yellow leaves or rotten roots. Today we teach you four ways to solve the problem of orchid decay in summer!

Diseases are the most common diseases of orchids in summer, and pests are easy to solve. Most of the diseases that can threaten the life of orchids are diseases, and insect pests can only assist diseases to threaten the life of orchids. The common diseases in summer are: carbon maggot disease, stem rot, white silk disease, soft rot, these four kinds, let's understand them one by one!

Before we explain these four diseases, let's first understand a problem. Most of the diseases of orchids are shown on the leaves. We observe the leaves of orchids through our eyes to see what is a disease and what is not. Now I will teach you a simple technique to easily understand that the yellow leaves from above to below are generally normal physiological phenomena or normal physiological diseases, so don't worry. Stop messing around. If the leaves are yellow from the bottom to the top, you have to pay attention to the yellow leaves, and you have to think of ways to treat them in time. You can kill the whole orchid plant in a few days when you get sick. Today, we will not talk about physiological diseases, but only about the four common diseases that do great harm to orchids!

First: carbon maggot disease, pathogen: fungi (Alternaria), the occurrence of orchid carbon maggot disease is first of all related to the weather, high temperature and humidity weather is the most easy to occur, Rain Water is more, high temperature and serious disease in early summer, especially in muggy environment. Black spots appear in the leaves at first, and then the area gradually expands, showing a sunken shape, there are often wheel lines, and the junction with healthy tissue is yellow or grayish green. In the later stage of the disease, the leaf tip or leaf edge is dry, and the dry part is generally gray-white, which can be spread with the wind, along with diseased seedlings, plant materials, orchid pots, etc., which is highly contagious, although it will not cause orchid death, it will greatly reduce the ornamental value of orchid grass, shade when the temperature is higher than 25 ℃. Pay attention to ventilation, do not spray foliar water, once the diseased plant should be cut off in time, so as not to become a source of infection, the following picture shows carbon maggot disease.

Second: stem rot, pathogen: fungi (Fusarium oxysporum), often occur in pseudobulbs, old seedlings, new seedlings, the first leaf base appears water stains, and then gradually browns and blackens, yellowing from the heart leaf, spreading from the leaf base to the top of the leaf, at the same time, pseudobulbs atrophy and yellowing until withered, and the pathogen can spread with diseased seedlings, plant materials, orchid pots, etc., which is highly contagious. Attention should be paid to control the humidity of plant materials. And pay attention to the ventilation of the cultivation environment, spray carbendazim or chlorothalonil and other fungicides once every 15-30 days. Once stem rot occurs, if measures are not taken immediately, the result is generally "covered in the whole basin". The infected false bulb (Reed head) should be removed immediately and disinfected with carbendazim or chlorothalonil, the orchid basin also needs to be sterilized, and then the new plant materials should be replaced, and the previously used plant materials should be abandoned. If you do not want to give up can be used after high-temperature cooking, the following picture shows stem rot.

Third: White silk disease, the pathogen: half-known subphylum fungi, also known as white filariasis, Sclerotinia sclerotiorum. The disease began to infect from April to May, and the disease occurred rapidly during the peak period from June to August, resulting in the rot and death of the injured orchid plants. the disease began from the stem near the ground, showing a yellow to light brown running water spot, and then browned to black brown rot. and spread on the surface of the rhizosphere soil and at the base of the stem, destroying the stem and infecting young leaves and roots, leaf sheaths and roots produce white hyphae. The injured site is waterlogged, decaying and softening, blackening, until the leaves wither, the bacteria spread to the false bulb, the sclerotia changes from white to russet to tea-brown necrosis, and in serious cases, the whole plant dies and is contagious. can be spread by running water, irrigation water, Rain Water splash and fertilization, the soil is sour, the disease is the most serious, high temperature and humid weather is easy to induce diseases, prevention methods: pay attention to ventilation, increase the acidity and alkalinity of plants It can be solved by spreading grass wood ash, or fungicides such as carbendazim, chlorothalonil, methyl topiramate, potassium permanganate and so on can be used.

Fourth: soft rot, pathogen: bacteria (soft rot), which mostly occur on the new seedlings in the same year. At the time of the disease, there are small brown spots at the base of bluegrass, then expand rapidly, and finally dark brown rot patches with foul smell appear. Gently pull off with your hands, it is also easy to occur in high temperature and humidity weather, mainly through wound infection, we should pay attention to ventilation to avoid wound infection. Once the infection is found, the infected false bulb (Reed head) should be removed in time, and the new plant material should be replaced and put into the basin again after disinfection. Prevention and control of orchid soft rot should avoid or reduce the occurrence of wounds, such as seedling incisions, undersea buds, pests and other wounds, the picture below is soft rot!

The first three diseases are caused by fungi, and the latter one is caused by bacteria. Diseases caused by fungi are treated with antifungal drugs, and diseases caused by bacteria are treated with antifungal drugs, which can be effectively prevented and treated. There are fewer detours, and the truth and methods are all taught. Finally, I wish you can easily raise orchids and let orchids safely through the hot summer! Author: Mei Fei, founder of Orchid Bar Forum, Secretary of Orchid Association of Jingshan City, Hubei Province, online celebrities of orchid industry on major self-media platforms! I will publish orchid knowledge and pictures every day, take you in-depth understanding of orchids, teach you to easily raise orchids, you can always ask me or leave a message below if you don't understand orchids, if you like, you can follow me or collect or forward to help others!