Prevention and control of common diseases and insect pests in Cymbidium

1. Leaf blight

Symptoms: the disease occurs on the front of the leaves, starting from the tip and edge of the leaves, initially brown dots, then expanding into semicircular dry withered spots, shrinking spots, grayish brown in the center, and water-stained dark brown bands on the edge. the black and brown dots (pseudocyst) on it are arranged in a concentric circle. The pathogen is Colletotrichum. Disease characteristics: it occurs all the year round, especially in greenhouse cultivation, but the disease degree is lighter than anthrax.

Prevention and cure method

① should strengthen greenhouse management, control greenhouse humidity by timely ventilation, apply fully mature fertilizers, make rational use of nitrogen fertilizer, and increase the application of scale and potassium fertilizer.

Disease-free seedlings were cultivated by ②.

③ removed the sick and disabled body in time.

At the initial stage of the onset of ④, 64% alum wettable powder was sprayed 500x, 50% mixed thiophanate suspension, or methyl thiophanate wettable powder 500x liquid, or 1 200 Bordeaux solution, one of which was sprayed twice every 10 to 15 days, and the control effect was more than 90%.

2. Brown spot

Symptoms: the disease occurs on the leaves of Cailan, which is dark green watery spots at the beginning, and then expands into round or irregular spots, which are sunken in the center, showing reddish brown to grayish brown, and the texture is harder than anthrax. The disease spots can penetrate both sides of the leaves, but will not perforate, producing reddish-brown dots on the front of the leaves, which is its conidium. Sometimes there are diseased leaf hybrid anthracnose.

Prevention and control methods:

① high temperature and humidity, shed roof dripping, these are the conditions of the disease, so in summer and autumn high temperature season should pay attention to shading, ventilation, cooling, dehumidification, early disease prevention measures.

From the initial stage of the onset of ②, 40% nail cream copper wettable powder 600 × 700 times solution, 64% alum wettable powder 500 times liquid, 36% thiophanate methyl suspension 400 times 500 times liquid, choose one of them, once every 10 days or so, continuous prevention and treatment for 2 times.

III. Anthrax

Symptoms: the disease occurs in the leaves of Cailan, the disease spot is round or nearly round, the center is gray-white, sunken, the edge is dark brown, penetrating both sides of the leaf, showing a thin film, or even perforation. On the disease spots on both sides of the leaves, occasionally there are conidia with small black spots as pathogens, and most of them are pink myxospore clusters, especially under wet conditions. The pathogen is anthrax, so it is called anthrax.

Prevention and cure method

First of all, ① should select good varieties with strong disease resistance and avoid varieties with poor quality and high purity.

② selected disease-free nutrient soil, or soil disinfection to reduce the source of primary infection, and increased application of scale potassium fertilizer to improve plant disease resistance.

③ strengthens the management of the greenhouse and carries out ecological control, that is, ventilation and dehumidification to keep the humidity in the greenhouse at about 60% and reduce foliar water spraying.