During the growth period of watermelon, the farmers will always encounter various diseases. What are the common diseases of watermelon, how to prevent it? Today, Xiaobian will lead everyone to identify and control:
What are the common diseases of watermelon?
1. Watermelon blight: Watermelon blight can occur in all parts of watermelon throughout the growing season, especially in the vine stem and tender stem nodes. Rainy, high temperature and continuous cropping are conducive to the occurrence of the disease. Get suppressed. The seedlings can cause rotten buds before they are unearthed, and the round leaves are hot and dark green spots on the cotyledons. The center of the lesions gradually turns reddish brown, the base of the stems is obviously collapsed (thinning), and the growth points and young leaves are rapidly wilting until they fall. Withered. The adult stage is mainly harmful to the vine stem section. It is dark green water-stained plaque at first, and the diseased part is obviously curled up. It is dark brown rot when wet and dry and dry when it is dry. The vine leaves above the victim are withered, often a vine Can be victimized in several places. Most of the leaf damage forms round or irregular water-stained large spots at the leaf edge. When the weather is wet, the edge of the lesion is not obvious, and the expansion is rapid, often causing the whole leaf to rot. When the weather is dry, the edge of the lesion is dark green. The middle is light brown to blueish white, dry and fragile. The fruit is damaged, mostly occurs in the flower buds, and the dark green round or nearly round water-stained sag spots can be expanded and the whole fruit can be expanded; the diseased fruit shrinks and rots, has a stench smell, and the disease minister has white mildew. . Fruits during transport and storage can also be rotted.
2. Watermelon leaf blight: Leaf blight can occur in all parts of watermelon during each growth period, but leaf blight caused by leaf damage has the greatest impact on yield and quality. Continuous cropping, rainy, high humidity, and partial application of nitrogen fertilizer are beneficial to the occurrence and prevalence of diseases. Freezing damage can aggravate the occurrence of diseases. The seedlings of the seedlings are damaged, mostly in the leaf margins, initially water-stained small spots, and then expanded into light brown to brown, round or semi-circular water-stained lesions, which can spread to the whole cotyledon under high humidity, causing cotyledons withered. The true leaves are damaged. The lesions occur mostly between the leaf margin and the veins. They are initially water-stained spots (especially obvious on the back of the leaves). They quickly merge and infiltrate under high humidity, causing the diseased leaves to lose water and dryness. In dry weather, a round to nearly round brown spot with a diameter of 2-3 mm is formed, which is covered with leaf surface. Then, in the case of wet weather, it can be merged into irregular large brown spots, and the lesions become thinner. In severe cases, the leaves are dry. On the vine stem, an elliptical to fusiform, slightly concave light brown spot is formed; the fruit is a rounded dark brown spot with a slight bulge around the fruit, which can penetrate the flesh and cause the fruit to rot. A black mold layer can be grown on the surface of each affected part.
3, watermelon anthracnose: seedling stage cotyledon edge into a round or semi-circular dark brown lesions, surrounded by a yellow-brown halo, near the ground stem base dark brown, collapsed, tripped. The diseased part is black with small grain spots. When the humidity is high, the pink viscous material on the lesions is formed. The leaves of the adult plants form irregular or round dark brown water-stained oval black-brown, concave lesions. When the spot circumscribing the stem for one week, the leaves and plants are dead, the young melon is damaged, and the blister-like plaques of dark green slightly bulge are formed at first, and then rounded brown spotted lesions are formed in the water-stained depression, and pink viscous substances are formed on the lesions. It is in the shape of a wheel. In severe cases, the lesions are contiguous, cracked, and rotted, and many small black spots are formed on them. Watermelon anthracnose can occur in all growth stages of watermelon. It is more harmful in the middle and late growth stages, and the leaves and melons are seriously damaged. The disease develops rapidly at moderate temperature (24°C-26°C) and high humidity. When the daily average temperature is higher than 32°C, the disease can be inhibited, but the fruit anthracnose in transportation and storage can still occur seriously, causing susceptible varieties. The fruit is rotted in large numbers. The flowering period from long flowering to long fruiting is the peak period of anthrax.
4. Watermelon virus disease: Watermelon virus disease has been on the rise in recent years. Seeds can be poisonous, but the main media for drug transmission are aphids and other minor insects. After the mites suck on the juice of the diseased plant, they move to the ground and take the virus to the healthy plant. In addition, the pruning and pressing of the fields give the virus a chance to spread. There are two types of mosaic and fern. Fern leaf types are more common than mosaic types. The fern leaves show that the upper heart leaves are narrow, slender and distorted. High temperature, drought, heavy mites, and weak plants are all serious. The mosaic showed that the whole plant showed mosaic symptoms. In the early stage of the disease, the leaves show deep and shallow mosaics, and then form acne or wrinkle deformities, and the leaves are narrow. Lightly diseased plants can still bear melons and melons; small diseased plants have few or no melons, stem segments are shortened, new stems are slender, and plants are atrophied.
5, watermelon blight: all parts of the watermelon can occur in the whole growth period, causing leaf vines and other dead, high humidity and rain, continuous cropping, partial nitrogen fertilizer is conducive to the occurrence of disease, high temperature and drought, the disease gradually slows down with. Bacterial wilt mainly occurs on stems and also invades leaves and fruits. On the stems, the gray-white ellipse is formed near the nodes to irregular lesions. Small black spots on the lesions, and the lesions surround the stems and tillers in severe cases. The leaves are infected, the lesions are round or irregular, dark brown, and small black spots on the lesions. When the humidity is high, the lesions rapidly spread to the whole leaves, and the leaves become black and dead. When the melon is infected, it begins to produce water-stained lesions. After the central part of the lesion is brown, it is star-shaped and cracked. The inside is cork-like dry rot and finally rots.
Bacterial wilt and blight are very similar in the field and easy to mix. The main difference is that there is no abnormality in the roots of the blight, and the internal vascular bundle is not discolored, but the wilt is rotted, and the internal vascular bundle is browned.
6, watermelon wilt: also known as wilt disease, vine disease. The typical symptoms are wilting. The leaves at the base of the stems of the diseased plants are wilting, seemingly lack of water, obvious at noon, and can be restored in the morning and evening. The base of the diseased stems is yellowish brown, the base is curled up, and often the brownish brown gum overflows. The root of the disease turns brown, and there is a pink mold layer on the vine when it is wet. Watermelon wilt can occur from seedling to maturity, with the most serious disease in the end. Mainly from the roots to the onset, until the vascular bundle tissue, causing the catheter to brown, leaves wilting, yellowing, root browning, rot, the whole plant withered and died. Often caused a large area of ​​whole plant death, watermelon severely reduced production. Since watermelon blight pathogens can survive for 5-6 years in the soil, continuous cropping can aggravate the occurrence of diseases. The occurrence of watermelon wilt is closely related to climate and soil. The soil is sticky, the terrain is low, the drainage is poor, the cultivation is extensive, and the land preparation is uneven. It is unfavorable to the development of watermelon roots, and the incidence will be aggravated. The soil temperature is at 24-30 °C, and the disease occurs faster when it is rainy and humid; excessive drought is also easy to develop.
Common disease prevention and cure of watermelon
I. Agricultural control
1. Clean the countryside. First, the weeds along the ditch road near the melon field should be cleaned to reduce the host available in the early stage of the pest; second, the host of the watermelon mosaic virus is widely distributed, and the pest may be poisoned into the melon field after the pests endanger the weeds, and the impurities near the melon field are removed. Grass plays an important role in preventing pests and diseases; the third is to pay attention to clear the diseased plants of watermelon. The diseased plants should be removed and buried or burned, and should not be discarded in the ditch or on the side of the road.
2. Foliar topdressing. Melon farmers generally pay great attention to the application of base fertilizer, and foliar topdressing is also an important part of fertilizer application. When 0.2% potassium dihydrogen phosphate is combined with spraying pesticides, it can enhance the growth of the plant and improve the disease resistance. For plants with weak growth, it can increase the urea mixed spraying by 0.2% to 0.3%. Foliar fertilization of the diseased watermelon plants can also play a role in slowing down the disease.
Second, biological measures prevention
1. Use biological pesticide 2% Ningnanmycin 200 ~ 250 times solution, spray control before or before the onset of viral disease.
2. Aphids can be controlled by spraying with 0.9% worms 3000 times.
Third, chemical prevention
1. After the emergence of watermelon, it is easy to cause catastrophic disease, spraying 66.5% Plex water agent 1000-1500 times liquid, or 64% anti-virus WP WP 400-500 times liquid, etc., can play an effective prevention and treatment.
2. For the control of blight, use 50% carbendazim WP 2 kg, mix 100 kg of fine soil, apply to the planting hole, or use 50% carbendazim WP 500 times, or 70% after planting. The methyl thiophanate 1000 times solution was irrigated once, 250 ml per hole, and the occurrence of anthrax was also prevented. In the early stage of wilt disease, after the wilt diseased plant was found, the rhizosphere of the diseased plant was taken as the center, and a circular pit with a depth of 8 to 10 cm and a radius of 10 cm was dug, so that the main root portion was exposed, and 50% carbendazim WP 500 was used. Double solution or 70% methyl thiophanate 1000 times solution rooting, 500 ml per hole solution, can cure the blight.
3. For the control of blight, spray 70% methyl thiophanate 800 times solution or 64% anti-virus WP 1500 times solution.
4. Prevention and treatment of viral diseases The main cause is the spread of aphids and the prevention and treatment of viral diseases. It should be sprayed with 20% imidacloprid 1500 times before the peak of aphids. The protection site can be fumigation method, using 1.5% sputum smoke agent 300g per 667 square meters, evenly distributed in the shed, and the greenhouse will be sealed in the evening, ignited in turn, and the wind will be released after 12 hours in the closed shed; 80% dichlorvos can also be used. 667 square meters with 150 ~ 200 grams of fumigation, evenly distributed in the greenhouse, piled up a small pile of sawdust at each point, ignited and poured on the dichlorvos fumigation, this method is generally carried out around noon during the day, when the temperature in the shed reaches 30 °C, smoked Ventilation after 2 hours. The virus plant was found to be sprayed with 20% virus A600 times solution, and sprayed once every 7 days for 2 to 3 times.
5. Prevention and treatment of anthrax can be carried out in the early stage of the disease, spraying 80% of anthrax tofu 800 times solution, or 70% of methyl thiophanate WP 500 times, or 50% of WP WP 400 to 600 times. The protective ground can be smoked and fumigated, with 45% chlorothalonil smoker per 200 to 250 grams per 667 square meters, and 8 to 10 days of smoked once, and can cure the disease at the same time.
6. The leaf miner uses the larvae to sneak out the mesophyll in the leaves, forming many curved stalks in the leaves, mastering the adults to control the adults in time, or spraying the larvae when the stalks appear. It can be sprayed with 0.9% worms 3000 times solution, or 40% green broccoli 800 times solution, or 25% Aikas 1000 times solution, or 40% eucalyptus emulsifiable oil 1000 times solution.
7. Sterilization, insecticide and fertilizer mixed fungicides, insecticides and potassium dihydrogen phosphate for foliar application can not be mixed with anti-virus cockroaches, and other bactericidal and insecticides can be mixed. The general pesticide can be kept for about 7 days on sunny days, so the pesticide should be sprayed once every 7 days, so that the double effect of preventing pests and diseases and promoting the robust growth of watermelon plants can be achieved.
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