How is watermelon anthrax recognized?

Watermelon anthracnose mainly affects leaves, but can also damage stems, petioles, and fruits. Round or semicircular brown or black-brown lesions appear on the edge of the seedlings' affected cotyledons, and there are often black-brown halos on the periphery, and small black spots or light red sticky matter are often scattered on the lesions. The stem near the ground is damaged, and the base of the stem turns black-brown and becomes thin and cataplexed.

The melon vine or petiole is infected, at first it is a water-soaked yellow-brown oblong spot, slightly concave, and then turns black-brown, and the lesion surrounds the stem for a week, and the whole plant dies. The leaves are infected, and at first they are round or irregularly shaped water-stained spots, sometimes with wheel lines, and the lesions are easy to break and perforate when dry. When wet, a pink sticky substance is formed on the lesion.

At first, the fruit is a water-soaked depression-shaped brown round spot or oblong spot, which is often cracked, and when the humidity is high, pink sticky matter is produced on the spot.

The disease of watermelon seedlings can harm the cotyledons and stem base of seedlings. When the cotyledons grow, the edges of the cotyledons will appear round or semi-circular brown lesions, and the periphery of the lesions is usually yellow-brown halos. Small black particles or reddish sticky substances will grow on the lesions;

At the base of the stem, the tissue becomes blackish-brown and shrinks and cataplexy.

1. The pathogenesis stage of watermelon anthracnose can occur from seedlings to maturity; 2. The disease site can occur on leaves, vines and fruits; 3. The specific manifestations of the disease, when the seedlings are sick, the stems and vines near the ground turn black-brown, shrinking and cataplexing.

When the leaves are damaged, they start as small yellow water-stained round spots, which later expand into brown spots. The spots are surrounded by purple black circles with small black spots or pink sticky substance, the spots gradually expand, connect with each other, break when dry, and the leaves dry up and die. Narrow brown depressions appear on the petioles and stems, the scars expand, and the stems and vines gradually die.

Mainly harmful to leaves, but also to stems, petioles, and fruits. Seedlings have round or semicircular brown or black-brown spots on the edge of the cotyledons, always with a black-brown halo on the periphery, and small black particles or reddish mucus scattered on their bottle trays.

The trunk near the ground is damaged, the base of the stem turns blackish-brown, shrinks and becomes tapered. Infected with Kua Wan or petioles, it is a waterlogged yellowish-brown round spot at first, which turns black and brown after a slight depression, and after a week of diseased spots around the stem, the whole plant withers and dies. Phyllitis is initially a round or irregularly water-stained spot with sometimes a ring pattern that breaks easily when dry.

When wet, a pink, sticky substance is produced in the bottle. Fruit hair dyes are initially water-soaked concave brown round or oblong spots that often crack and appear pink sticky when humidity is high.

Watermelon anthracnose has a great impact on watermelon production, and if it is not sold well, the economic effect will also be affected. One of the main diseases of watermelon, so it is necessary to understand and prevent the occurrence characteristics of watermelon anthracnose. Anthrax is the main ill of watermelon growing by farmer friends.

The loss of diseased fields is 10% to 30%, and the loss of heavy fields is more than 60%, which can lead to water conservation in severe cases. Watermelon anthracnose can occur from seedling to maturity. Onset may occur on leaves, vines, and fruits.

The disease specifically shows that when the seedlings become ill, the nearby ground stems turn black-brown and suddenly retreat. (William Shakespeare, "Hamlet", "Disease Sayings") to strengthen cultivation management, anthracnose plastic greenhouses should be planted every three to four years watermelon or other melon crops. Proper dense planting, timely adjustment of plants, so that the field is well ventilated.

Watermelon anthracnose can occur on leaves, vines, and fruits; The specific manifestations of the disease, when the seedlings are sick, the stems and vines near the ground turn black-brown, shrink and cataplexe, and the optimal temperature for the onset of watermelon anthracnose is 22 27, and the lesions below 10 and above 30 stop growing.

Disease resistant varieties were selected, and different watermelon varieties had different resistance to anthrax. On the basis of the selection of disease-resistant varieties, the seeds were disinfected before sowing.

Do a good job of pruning, pressing vines, and beating branches, maintain a good ventilation and light transmission environment in the field, and strictly prohibit flood irrigation.

In the early stage of the disease, remove the diseased leaves in time and spray them for protection.

It is necessary to judge by the shape of the watermelon. At the beginning, there will be round brown spots on the leaves, and then the spots will slowly expand to later lead to the death of the rhizome, be sure to spray pesticides, but also use organic fertilizer, pay attention to fertilizer and water management, but also timely ventilation, do not plant too dense.

The disease can be identified by its symptomatic presentation. Disinfectants can be selected for prevention and control. Some pesticides can also be selected for control.

Watermelon Anthracnose Symptoms:Watermelon anthracnose can damage the leaves, leaf stalks, vines, fruit stalks and fruits of watermelons.

The leaves are infected, and the leaves have yellow water-stained round spots at the initial stage of infection, and the later spots gradually expand and are attached to concentric ring patterns, and the lesions are centimeters in diameter, easy to perforate, brown, and the outer edge is often accompanied by a yellow halo. Usually the lesions are more uniform in color, with scattered black dots on them, and when the ambient humidity increases, a pink viscous gelatinous substance appears.

In the later stage, the diseased leaves are prone to dry up and break and premature senescence. When watermelon seedlings are sick, they first appear brown round lesions on the cotyledons, and then the base of the young stem turns black-brown, shrinks, or even folds upside down.

At the onset of the adult plant, there are light yellow water-stained round spots on the leaves, which turn brown in the later stage, the edges are purple-brown, the middle part is light brown, and show concentric wheel lines, and the lesions are easy to cause perforation and dryness after expanding and fusing with each other.

The petiole or vine is infected, and the initial appearance is a water-soaked yellow-brown fusiform or oblong concave lesion, and then the lesion gradually expands and turns black-brown, and the lesion can overflow and perforate, and finally causes the plant to fold and die.

The fruit stalk is infected, and the young fruit is dark in color at first, and then gradually shrinks to death. The fruit is infected, initially as a dark green oil-stained small spot, and then gradually expands into a round dark brown lesion with a concave surface and a ring pattern, usually with the growth of the lesion, cracks will appear in **.

When the air humidity is high, small black particles appear on the lesions, and there are pink sticky conidia masses, and in severe cases, the lesions are patched and the watermelon rots.

Infection cycles

The melon anthrax fungus mainly overwinters on diseased plants or in the ground. The seeds carry the fungus, and the mycelium attached to the mucous membrane of the seed epidermis can also overwinter. In addition, melon anthrax bacteria can also live a certain saprophytic life on old wood in greenhouses or plastic greenhouses.

A large number of conidia produced by melon anthrax on overwintering organs are an important source of primary infection in the field.

The melon anthrax fungus latent inside the seeds can directly cause disease in seedlings. The conidia formed on the lesions of the year were re-infected. During harvesting, the conidia are transported by humans, insects or splashed by wind and rain, and spread to the gourd, and continue to infect the melon during accumulation and storage.

Watermelon anthracnose occurs throughout the growth period of watermelon, but the onset is more severe in the middle and late stages. In acidic soil cultivation, low-lying terrain, poor drainage, excessive density, poor ventilation, excessive nitrogen fertilizer, etc., the disease can cause and aggravate the occurrence of the disease. Therefore, in the prevention and control of watermelon anthracnose, on the basis of doing a good job in comprehensive prevention and control, we should focus on selecting disease-resistant varieties, cooling and draining moisture, and doing a good job in protecting the whole growth period.

1. Select high-quality disease-resistant varieties. Reasonable crop rotation and avoid continuous cropping. Seeds and seedling soil are strictly disinfected to cultivate disease-free and robust seedlings.

2. Strengthen the field cultivation management of liquid limbs. Reasonable dense planting, the use of soil testing formula fertilization technology, increase the application of organic fertilizer, phosphorus and potassium fertilizer. Improve the ventilation and light transmission conditions in the field, promote the healthy growth of plants, and improve the disease resistance of plants.

If diseased leaves and fruits are found in the field, they should be removed in time and taken out of the field to be buried and destroyed.

3. Pharmaceutical prevention and control. In the early stage of the disease, you can choose to spray evenly with 1500 2500 times of 50% Shibaogong wettable powder, 800 times of 80% anthrax Fumei wettable powder, 800 times of 70% methyl tobuzin wettable powder or 800 1000 times of 10% Shigao moisture dispersible granules. Spray every 7 to 10 days, 2 to 3 times in a row.

1. Prevention and control methods of watermelon anthracnose

1. Choose high-quality disease-resistant watermelon varieties, and disinfect seeds and seedlings before watermelon seedlings and transplanting, which can effectively reduce the source of disease.

2. Avoid heavy planting, and it is recommended to implement crop rotation with non-melon crops.

3. Strengthen the application of well-rotted farmhouse fertilizer and microbial organic fertilizer, not partial application of nitrogen fertilizer, more phosphorus and potassium fertilizer, increase the potential of watermelon seedlings, and improve disease resistance.

4. Watermelon is suitable for planting in sandy soil, to prevent water accumulation on a flat ground, pay attention to ventilation and drainage in precipitation, and use drip irrigation to water in a dry environment, and can not flood irrigation, reduce the humidity of watermelon planting and reduce the occurrence of diseases.

5. Reasonable control of planting density and increase light transmission and ventilation can make the photosynthesis of watermelon achieve the best.

6. After watermelon fruit setting, mancozeb, pyrazole dysen, chlorothalonil, difenoconazole and other agents can be sprayed for disease prevention.

7. After the onset of the disease, it is recommended that farmers choose 800 times of 70% methyl tobuzin wettable powder and 2500 times of 25% pyrazoxystrobin emulsifiable concentrate for prevention and control, and spray once every 7 days, and the effect is very good.

2. Symptoms of watermelon anthracnose

1. Leaf infection.

When the leaves are damaged, there will be yellow water-stained round spots, which will expand to brown later, and the lesions will be easily perforated, and dark red mucus will appear in humid environments.

2. Infection of melon vines or petioles.

At first, it is a water-soaked yellow-brown oblong spot, slightly concave, and then turns black-brown, and the whole plant dies after the lesion surrounds the stem for a week.

3. Fruit infection.

At first, there will be small dark green water-stained spots, and then they will expand into round lesions, with neat edges, sunken, dark brown, and cracked fruit rot.

At this point, the introduction of watermelon anthracnose prevention and control is here, if farmers want to grow high-yield watermelons, we must master scientific planting skills and pest control methods, so as to effectively improve the efficiency of watermelon planting.

You can use drugs to prevent and control it, or you can use some more nutritious fertilizers, so that you can prevent the appearance of this disease, so that watermelons can grow particularly well.

At this time, pesticides should be sprayed in time, and then timely watering and fertilization are also needed, and then it is also necessary to ensure the right planting temperature and humidity control, and it is also necessary to kill insects in time.

To choose a good watermelon variety that is resistant to diseases and pests, the seeds should be disinfected before sowing, and soaked with chemical agents, weeds should be removed in time, pesticides to prevent diseases and pests should be sprayed, vines should be pruned in time, diseased leaves and fruits should be removed in time, and fertilization and top dressing should be carried out in time.

It is necessary to learn the antiviral varieties in advance, combine the local climate and environment, disinfect the seeds before sowing, and remove the diseased leaves and fruits in time at the early stage of the disease to prevent the spread.

It is necessary to spray pesticides, choose the right varieties for planting, and be sure to effectively defend against them in daily planting.

Prevention and control methods:

l) Select disease-free seeds and seed treatment, soak seeds in 55 warm water for 15 minutes, soak in 25-30 water for 2 hours after cooling; Or soak the seeds with 10% trisodium phosphate solution for 20 minutes, and wash with water to promote germination after removal.

2) Concentrate on seedlings, or spread silver-gray film in the field to avoid aphids. It is best not to plant melon crops around 400 meters of melon fields. Early seedling transplanting, strengthen water and fertilizer management, and advance the development stage by 10-15 days. Field management should avoid the spread of sap.

3) Timely prevention and control of aphids, which can be controlled with 2000 times of 5% Riflin emulsion and 3000 times of 10% aphid lice net wettable powder.

4) At the early stage of the disease or the plants with mild susceptibility, use 40g of Olik watermelon virus mixed with 15kg of water, not compounded with other chemical drugs, sprayed once every 3 days, sprayed 2 3 times in a row, can effectively control the speed of infection.

5) During the growth of the plant, if there is a long-term drought and no rain, it will cause serious boron deficiency in the plant. Boron fertilizer mixed with "gold ingot" trace element liquid fertilizer, foliar spray once every 7 days, can prevent the occurrence of viral diseases.

The appearance of watermelon anthracnose and leaf blight is similar, the biggest difference is that the lesions of anthracnose are often scattered with small black particles or light red sticky, while the lesions of leaf blight only make the leaves dehydrated and wilted, which is relatively clean. See ** Comparison (anthrax on the left, leaf blight on the right):

Watermelon anthracnose is caused by the fungus infection of the subphylum Acanthospora hemiphyta, and the optimal temperature for its onset is 22 27, and the lesions stop growing below 10 and above 30. Leaf blight is caused by the fungus infection of Alternaria spp., the growth temperature limit of the bacterium is 3 45, 25 35 is suitable, and 28 32 is the most suitable.

Leaf blight is a dry, brittle leaf. Charcoal tooth disease is a little bit, like plum blossom dots.