Control methods of watermelon leaf blight

Leaf blight is one of the common diseases of watermelon, more than summer and autumn watermelon disease, spring crop watermelon can also be disease, general incidence rate of 10~30%, serious plot disease rate of more than 80%, so that a large number of leaves die, significantly affect watermelon production, in addition to harm watermelon, but also harm melon, cucumber, wax gourd, pumpkin and other cucurbitaceae plants, the following to take a look at watermelon leaf blight control method it!

harm characteristic

Watermelon leaf blight mainly damages leaves, but also damages stems and fruits. Seedling cotyledons are damaged, mostly occurring at leaf edges. At first, they are water-stained spots, then they expand into brown water-stained spots, circular or semicircular spots. Under high humidity conditions, they can damage the whole cotyledons and make them wither. True leaf damage, mostly occurs in leaf margin or vein, initially water-like dots, in high humidity under rapid merger, penetration, so that leaves dry and withered. High temperature dry weather, the formation of 2~3 mm diameter of the circular brown spot, wet weather, can be merged into a large brown spot, thin spots, serious leaf caused by withered. Stems and vines are damaged, producing oval or fusiform, slightly depressed light brown spots. When the fruit is damaged, it produces dark brown spots around the slightly raised circular depression, which causes the fruit to rot when it is serious.

occurrence regularity

The pathogen of watermelon leaf blight is not strict to temperature, temperature 14~36℃, relative humidity higher than 80%, field rainy days, rainfall, relative humidity higher than 90%, easy to epidemic or large occurrence, wind and rain conducive to the spread of the pathogen, resulting in widespread occurrence of the disease, continuous cropping, partial or heavy application of nitrogen and poor soil, plant disease resistance is weak and serious. Continuous sunny days and long sunshine hours have an inhibitory effect on the disease. There were differences in disease resistance among varieties, Jinzhong and Guannong were more susceptible. In recent years there has been a growing trend of serious, production should pay attention to.

control methods

1. To establish disease-free field, select disease-resistant varieties suitable for local cultivation. At present, the disease-resistant varieties include Zhengzhou 5, Zhengza 7, Xinong 8, Yueyou 2, Fuzhou watermelon, Xinhongbao, etc.

2. After watermelon harvest, pay attention to removing sick and disabled bodies, bury them deeply or burn them, and do not pile up sick and disabled bodies at the edge of the field.

3. Adopt formula fertilization technology, apply compost made of enzyme bacteria, avoid partial application of nitrogen fertilizer, spray Huimanfeng liquid fertilizer before sitting melon, 320 ml per mu 500 times water, improve disease resistance.

4, scientifically determine the sowing time, open field should be in the daily average temperature stable at 15℃ above, 5 cm deep soil temperature stable at 12℃ above sowing, if you want to rush early can be covered with plastic film to reach the above temperature before sowing.

5. Soak seeds with 75% chlorothalonil WP or 50% diaphanil WP 1000 times solution for 2 hours, rinse and germinate seeds.

6, there are conditions to promote the use of rain shelter cultivation method, open watermelon after rain to pay special attention to ditch drainage, to prevent moisture retention, to reduce the disease has an important role.

7. Using frame cultivation method, 1500 plants per mu, using single vine pruning, picking the first female flower when 6~7 leaves, retaining 12~13 leaves, not only increasing yield, increasing income, but also reducing the disease.

8. Before the disease occurs, when there is no disease spot, spray 50% Sukeling WP 1500 times solution or 50% Prohydantoin WP 1000 times solution, 75% Chlorothalonil WP 600 times solution, 70% Mancozeb WP or dry suspension powder 500 times solution, 80% Dasheng WP 600 times solution. Spray 60 liters of good solution per mu, once every 7~10 days, and continuously control 3~4 times.