Symptoms and prevention methods of watermelon virus disease

Watermelon virus disease, also known as small leaf disease and mosaic disease, is one of the most common and most serious diseases in watermelon production. It has a great impact on watermelon planting. Here, the editor will introduce the symptoms and prevention and control methods of watermelon virus disease. Let’s take a look.

1. Symptoms of watermelon virus disease

1. Mosaic type

The diseased plants generally do not die, and the growth points of the young stems will curl upward, forming a "dragon raising its head". The leaves are yellow and green, uneven, forming mosaic. In severe cases, the leaves become smaller, the branches and leaves shrink, and grow in clusters.

2. Fern leaf type

The new leaves are long and narrow, wrinkled and twisted, forming "chicken claw leaves", and the diseased plants are difficult to set fruit. The surface of the diseased fruit has dark green and light green spots. The fruit becomes smaller and has irregular small protrusions, forming a "deformed fruit".

2. Prevention and control methods

1. Choose disease-resistant varieties. In production, we should try our best to select varieties with strong resistance to viral diseases for cultivation, so as to fundamentally control the occurrence of viral diseases.

2. Soak the seeds for disinfection. Before sowing or raising seedlings, scald the seeds with 55-60℃ hot water for 20 minutes, then soak them in 0.1% potassium permanganate solution for 30 minutes, or soak them in 10% trisodium phosphate solution for 20 minutes, then wash them with clean water and then sow them.

3. Cover with insect-proof net. During seedling raising and protected cultivation, 40-mesh insect-proof netting can be used to cover and isolate the plants to prevent insects from causing harm and spreading viruses.

4. Hang sticky insect boards. During the production period, yellow boards can be hung in the fields to lure and kill aphids, planthoppers, and leafhoppers. When aphids are seriously infested in nearby crops, silver-gray film can be laid to avoid aphids and reduce the influx of aphids.

5. Strengthen water and fertilizer management. Apply sufficient base fertilizer, increase the application of phosphorus and potassium fertilizers, spray foliar fertilizer appropriately, pay attention to drought prevention, water in appropriate amounts and at appropriate times to promote faster plant growth, healthy development, and improve disease resistance.

6. Mix seeds with medicine. Viral diseases are mainly spread by pests such as aphids, thrips, whiteflies, and Bemisia tabaci. Therefore, before sowing, you can mix the seeds with 70% thiamethoxam suspension seed dressing agent or 60% imidacloprid suspension seed dressing agent at a drug-seed ratio of 1:200, which can effectively prevent the damage and transmission of virus-transmitting pests in the seedling stage, and the effective period can reach 80-90 days.

7. Control by chemicals. Starting from the seedling stage, use 600 times diluted 5% amino oligosaccharide soluble powder + 4000 times diluted 50% nitenpyram soluble powder, or 600 times diluted 5% amino oligosaccharide soluble powder + 2000 times diluted 50% pymetrozine water dispersible granules, alternately, spray once every 10-15 days, spray 2-3 times a month, until spraying to the middle and late stages of crop growth, which can effectively prevent the occurrence of viral diseases throughout the entire growth period.

The above is an introduction to the symptoms and prevention methods of watermelon virus disease. The general disease rate of viral disease is 10%-20%, and in severe cases it can be as high as 50% or even a complete crop failure, causing great losses to production. Growers must take timely prevention and control measures.