Causes and Control Measures of Watermelon Viral Disease
Watermelon is one of the most popular fruits in summer, with a sweet and delicious taste and effects such as clearing heat and detoxifying and promoting urination. Watermelon is cultivated in many parts of China, and it can now basically be eaten all year round. During the process of watermelon cultivation, it is very susceptible to the harm of viral disease. Below, let us take a look at the introduction to the causes of watermelon viral disease and its control measures.
I. Causes of Watermelon Viral Disease
Watermelon viral disease is mainly caused by Melon mosaic virus and Cucumber mosaic virus, among others. The virus overwinters in viruliferous aphids, on the seed coat, and on certain perennial weeds, becoming the primary infection source for the following year. Aphids, planthoppers, thrips, flea beetles, whiteflies and other virus-transmitting insects, as well as transmission through contact during agricultural operations, are the main pathways for the spread of this disease.
II. Types of Watermelon Viral Disease
Watermelon viral disease is generally divided into the mosaic type and the fern-leaf type. Whichever type it is, the threat to growers is relatively serious.
In the early stage of the mosaic-type viral disease, yellow-green mottled patterns appear on the top leaves, which later become shrunken and deformed, with the leaves becoming smaller and the leaf surface uneven. The internodes of new stems and vines shorten, becoming slender and twisted, and fruit setting is reduced or absent.
In the fern-leaf-type viral disease, new leaves become narrow and elongated, shrunken and twisted, growth is slow, and the plant becomes dwarfed. Sometimes the top shows clustered growth without elongating, the floral organs develop poorly, and in severe cases no fruit can be set. In diseased plants that develop the disease later, the fruit develops poorly, forming deformed melons, and in some cases the fruit surface is uneven, the fruit is small, and the flesh is dark brown, greatly affecting yield and quality.
III. Control Measures for Watermelon Viral Disease
1. Apply sufficient base fertilizer: according to the ratio of nitrogen, phosphorus and potassium required for watermelon growth of 2.83:1:3.4, apply fertilizer in a balanced formula, and increase the application of a certain amount of fully decomposed organic fertilizer as much as possible to improve the disease resistance of the plants.
2. Seed treatment: before sowing, soak the seeds in warm water at 70°C for 10 minutes, or soak the seeds in a 10% trisodium phosphate solution for 20 minutes, then wash them clean with water and germinate them for sowing.
3. After emergence, promptly spray 500-fold dilution of Yashimanjing emulsifiable concentrate, or 500-fold dilution of 2.5% bifenthrin emulsifiable concentrate, which have a certain effect on virus-transmitting insects such as aphids, thrips and whiteflies.
4. In the early stage of the disease, spray on the leaves 16 grams of 22% enyl · copper sulfate wettable powder + 20 milliliters of 33% moroxydine aqueous solution + 30 milliliters of 0.9% Yashimanjing emulsifiable concentrate + 1 milliliter of 0.01% brassinolide soluble concentrate, or 16 grams of 22% enyl · copper sulfate wettable powder + 20 grams of 58.8% aminophenol · dextran · hydroxy wettable powder + 30 milliliters of 2.5% bifenthrin emulsifiable concentrate, mixed and diluted with 15 kilograms of water.
5. Strengthen cultivation management and increase the application of phosphorus and potassium fertilizers. Pay attention to drought prevention, water timely and appropriately, promote plant development, and enhance disease resistance. Carry out field agricultural operations such as pruning, removing side shoots, pinching off growing tips, and tying vines in a timely manner. Diseased plants and healthy plants should be handled separately to avoid artificial transmission. Weeds should be thoroughly removed to prevent insect transmission.