How to prevent and control mosaic virus disease in snake gourd? Detailed explanation of control methods
Snake gourd is an annual climbing vine; the stem is slender, much branched, with longitudinal ridges and grooves, covered with short soft hairs and sparsely with long soft-hairy stiff hairs. Snake gourd has a well-developed root system with many lateral roots and readily develops adventitious roots; the stem vine is slender and long, reaching 5-8 m in length; the stem is five-ridged and green, with strong branching ability; the leaves are green, palmately deeply lobed, with relatively round sinuses, and the leaf surface has fine down; the corolla is white, the flowers are unisexual, with male and female flowers likewise differentiated; male flowers are mostly in racemes, green in the bud stage and pale yellow-green when about to open; male flowers appear earlier than female flowers; generally female flowers begin to set at the 20th-25th node of the main vine, after which both the main vine and lateral vines can continuously set female flowers.
What is mosaic virus?
Mosaic virus is a virus parasitic on plants that is transmitted by aphids. Mosaic virus disease and gangrene (ring spot) mosaic disease usually occur together on the same plant as a complication, and the damage is very serious. Mosaic virus disease initially appears as partial or overall wilting of the leaves, showing yellow-white mottled mosaic patterns and wrinkling. Plants infected and diseased in the early growth stage grow poorly and do not form heads, resulting in heavy losses. In gangrene (ring spot) mosaic disease, many dark brown water-soaked spots or ring spots of 1-3 mm form between the leaf veins, and purple-brown water-soaked necrotic streaks appear on the veins and petioles. These symptoms also appear inside the head. In some plants, lesions appear on one side, causing the head to twist; in others, infection and disease occur in the late growth stage, with lesions forming only on the leaves inside the head.
Mosaic virus disease is transmitted by aphid vectors. After aphids feed on the sap of diseased plants, they carry the virus and transmit it when they transfer to feed on the sap of other plants. If virus-carrying aphids are isolated from plants for 3-4 hours, the virus is inactivated and loses its ability to transmit. Aphids are divided into winged and wingless types, both of which are active year-round; May-June and August are periods of frequent activity of the winged type, followed by an increase in reproduction of the wingless type. Therefore, for Chinese cabbage sown in August, in the early growth stage many winged aphids fly in from other cruciferous plants, and among them virus-carrying aphids can cause the occurrence of mosaic disease. When environmental conditions are suitable, the disease develops very rapidly. The pathogenic virus overwinters attached to the roots of perennial cruciferous plants such as the seed-production mother plant Indigofera, many diseased turnip plants, and Indian rorippa.
Snake gourd mosaic virus disease:
Symptoms: The disease occurs at both the seedling stage and the adult plant stage. On the top leaves of diseased plants, small mosaic mottling of uneven light and dark color appears, and in severe cases slight mottle mosaic also appears; the diseased leaves become smaller and slightly deformed. Diseased plants set few gourds, with slight mottling near the fruit stalk, and the diseased gourds are distorted. It occurs from June to August and is relatively common. The diseased plant rate is 30%-40%, and in severe cases reaches as high as 80%.
Pathogen: It can be caused by multiple viruses, but cucumber mosaic virus is the main one, belonging to a virus.
Control: You can choose 7.5% moroxydine hydrochloride (Keduling) aqueous solution at 500 times dilution, or 3.85% ribavirin (Bingdukang) soluble powder at 800 times dilution, 1.5% triacontanol copper sulfate sodium dodecyl sulfate (Zhibingling) emulsion at 800 times dilution, or 24% mixed fatty acid copper (Duxiao) aqueous emulsion at 800 times dilution.