Main diseases and control techniques of A. chinensis in greenhouse
The golden line orchid is a perennial rare Chinese herbal medicine with high ornamental value and medicinal value. Fujian, Taiwan and Zhejiang are the origins of Anoectochilus. The cultivation of A. chinensis in greenhouses is likely to cause disease due to changes in cultivation techniques such as nutrient levels and light and temperature conditions. This paper summarizes the pathogens, symptoms and pathogenic characteristics of diseases such as chalk disease, gray mold, stem rot and soft rot, and proposes prevention and control techniques for reference by growers.
Chalk disease
1.1 symptoms and characteristics of the disease
The pathogen is Sclerotiumrolfsii Sacc. During the spring and summer rainy season and autumn rain, it is the high incidence of chalk disease, which mainly damages the roots and stem bases, which seriously damages the growth of A. acuminata. At the beginning of the disease, yellow lesions appeared in the base near the substrate, which were water-stained and rapidly spread to the roots, causing the stems to rot and the leaves to wilting. Severe diseased parts produce white, radial filamentous hyphae that spread across the surface of the substrate. At the end of the disease, the mycelium will interweave to form a sclerotia sclerotium, which will begin to appear white, then turn yellow, and finally brown.
1.2 Prevention methods
Strengthen ventilation, reduce the humidity on the surface of the substrate, remove the diseased plants in time, and sprinkle lime. In the early stage of the disease, it was sprayed with Doolivia-Pythium oxysporum (1 million spores/g) 6000 times solution or 80% allicin 400 times solution.
2. Gray mold
2.1 symptoms and characteristics of the disease
The pathogen is Botrytis cinerea. Gray mold occurs in the March-June period of each year. The matrix is ​​too wet, the water on the leaves is poor, and the ventilation is poor, which may cause disease. Most of the pathogens begin to damage the leaves in the middle and lower parts of the plant, and then expand upward. At the beginning of the disease, water-like round lesions appeared on the edge or surface of the leaves. The leaf tissue around the lesions was chlorotic and red to pink. Then the lesions began to expand and the leaves appeared to rot. In the late stage of the disease, gray conidia are produced in the decayed part, which spreads in the air with the airflow, causing a large area of ​​disease. The initial stage of the stem was water-stained, and then the disease began to shrink and soften, causing the plants to fall.
2.2 Prevention methods
In the easy onset season, it is necessary to strengthen ventilation, reduce the relative humidity of the air, and find that the diseased plants are removed in time. In the early stage of the disease, 400 g/L of Shijiale Suspension 1500 times solution or 300 million cfu/g of Trichoderma harzianum WP can be sprayed 300 times.
Stem rot
3.1 symptoms and characteristics of the disease
The main disease and control technology of A. acuminata cultivation is Fusariun oxysporum. Stem rot is a soil-borne disease. When the soil temperature is 24 ~ 30 °C, it is suitable for the germination and growth of the pathogen. The degree of disease is significantly correlated with the amount of invasive bacteria in the soil. At the onset of the disease, water-stained yellow-brown lesions appeared on the base of the stem of the plant, which rapidly developed to around the stem for 1 week. The tissue of the diseased part was rotted and dried, and then collapsed into a linear shape, and the bottom leaves were yellowed. As the disease progressed, the plant collapsed and died.
3.2 Prevention methods
The substrate was sterilized before planting, and the diseased plants were found to be removed in time, and the matrix surrounding the diseased plants was removed. In the early stage of the onset, use 25% tebuconazole emulsifiable concentrate 3000 times solution or 40% myclobutanil WP 6,000 times solution.
4. Soft rot
4.1 symptoms and characteristics of the disease
The pathogen is Eruinia carotovora varAtrose ptica. Bacterial diseases, which are mainly infested by wounds and stomata, and may occur throughout the growth period. In the early stage of the disease, it is not easy to be found. In the middle stage, brown necrotic lesions appear on the epidermis about 3 cm from the base of the stem. The veins are brown and wet, and the middle and lower leaves are yellow. At the later stage, the whole plant becomes soft and withered, and collapses. The rotten parts have a foul smell.
4.2 Prevention methods
Wash the seedlings and soak them for 30 s with the agricultural streptomycin 72% wettable powder 5000 times before planting; minimize the mechanical damage during the planting process; use DuPont to kill 1500 times of the bactericidal 1500 times solution at the beginning of the disease.
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