What are the diseases of watermelons and their treatment, preventive measures

Watermelon diseases, their prevention and treatment are the main concerns of gardeners when growing this demanding melon crop. In addition to creating comfortable conditions for growing, watermelons need careful care and timely detection of signs of disease.

To avoid plant death, it is important to correctly identify the pathogen and eliminate it. Let's look at the most common diseases and ways to combat them.

What diseases do watermelons have?

Watermelon diseases are mainly of a fungal nature; isolated diseases are provoked by viruses. Almost any disease can leave a gardener without a harvest already at the seedling stage. Knowledge of the signs of the disease, treatment methods and constant monitoring of plants will allow you to keep the fruits safe and sound.

Anthracnose

Anthracnose is a disease that can cause significant damage to crops. As a result of damage to the melon crop by anthracnose, you can get rotten fruits and stunted plants. The causative agent is a phytopathogenic fungus.

Brown or yellowish spots of indefinite shape appear on the leaves of the plant; over time, the spots expand, then the ovary becomes deformed, development slows down or completely stops. Brown or black spots appear on stems and fruits.

For reference. The wet season is most favorable for the development of the disease.During the growing season, the infection is spread by insects, through inaccurate watering or by rain and wind.

To combat the disease, you need to establish a watering regime, eliminating excessive soil moisture and ensuring the plantings have adequate ventilation and light. At the initial stage of anthracnose manifestation, treatment of watermelon plantings with Previkur is allowed.

An important preventive measure is the destruction of post-harvest residues. Watermelons should be returned to their original site after 6-7 years, having first disinfected the seeds.

Root rot

Refers to fungal diseases. Pathogenic microorganisms infect the melon soil, then the root system becomes infected, then the plant completely. Characteristic signs of infection are brown, weeping spots at the bottom of the stem and root, yellowing and withering leaves, cracked and decaying roots.

Wet, cold weather and sudden temperature changes contribute to the development of root rot, so it is important to prevent the beds from overflowing, loosen the soil, and regularly feed the bushes.

Dried and weeds must be removed in a timely manner, and the soil must be periodically disinfected with a solution of potassium permanganate. Treat watermelons with Fundazol solution (0.1%).

Powdery mildew

The disease is characterized by the appearance of whitish spots with a powdery coating. The fungal infection first affects old leaves, then spreads to young leaves and shoots.

As a result, fruit development slows down and ovaries form worse. Watermelons become deformed and can become covered with various rots. The taste of the fruits is not juicy, with low sugar content.

Spraying affected plants with a solution of calendula, dandelion or garlic is effective.

Prevention measures:

• during the growing season, treat the melon crop with disinfectants (“Kuprozan”);
• Fertilize the plants with crushed chalk/lime every 7-10 days;
• Before sowing, soak the seeds in “Immunocytophyte”.

Downy mildew

Another name for the disease is downy mildew. It appears as large brown spots covered with an oily film. Symptoms also include drying leaves, a lilac bloom on the back of the leaf blade, and cessation of fruit growth. Infected parts of the plant turn brown and die.

Treat with copper oxychloride or Acrobat. The affected areas are cut off, and the sections are treated with activated carbon. Timely disinfection of garden tools, regular weeding and elimination of plant debris reduce the risk of infection.

Mosaic

Mosaic disease relatively rarely affects watermelons. There are two types of viral disease: cucumber mosaic and green mosaic. The type of pathogen and external signs differ significantly. With cucumber mosaic, adult plants are affected: the leaves are deformed, yellowish or light green areas are observed on them, and lumpiness and swelling are visualized.

Green mosaic is characterized by a convex swelling on the plant; mosaic coloring occurs quite rarely. Greenhouse plants are more susceptible to the disease.

For reference. The mosaic virus is more common in Kuban, Crimea, and the Caucasus region. The carrier of the virus in the warm season is aphids. In the cold season, pathogens can be plant debris, roots of perennial plants, and weeds.

Almost the only treatment option is complete crop destruction. A drug to eliminate the viral disease has not yet been developed.You can try to save the harvest by spraying the plants every 7 days with Karbofos, but only if signs of viral mosaic are detected in a timely manner.

Read also:

Causes and treatment of mosaic on cucumbers.

How to deal with fusarium blight on cucumbers: life-saving tips.

The most effective methods for treating Fusarium wilt.

Fusarium

A fungal disease that affects the root system of melons. It is difficult to detect fungal activity at an early stage, but with extreme care, warning signs are noticeable already when growing seedlings. A fungal infection can be present in the soil and live on plant debris for 5 years.

Symptoms include the appearance of orange spots on the roots covered with a light pink coating. Obvious external signs indicate that the disease is advanced; treatment in such a situation is useless. Sick bushes are removed, the soil is treated with a solution of copper sulfate. The remaining watermelons are treated with fungicides as a preventive measure. At an early stage, you can try to save the crop with an antifungal mixture: wood ash, colloidal sulfur (1:1), water.

Bacterial spot

This is one of the most common diseases of melon crops, which can kill up to 50% of plantings.

Signs of bacterial spot:

• the appearance of watery spots with a green-yellow edging, which merge over time;
• dark round growths on watermelons;
• blackening leaves.

Infected bushes are removed, but at the initial stage you can try to save the plant. To do this, cut off all the leaves that have even the slightest signs of infection, being sure to capture at least 0.5 cm of the healthy part of the leaf. After each cut, the knife is treated with alcohol.The soil must be disinfected, as well as equipment, containers and structural parts of greenhouses.

Rot (white, gray)

The disease develops only in conditions suitable for it: high humidity and cold weather. The causative agent is a parasitic fungus; the signs of white and gray rot differ slightly, as do the principles of treatment.

White rot is characterized by the appearance of a whitish coating on the lower leaves (reminiscent of cotton wool), the structure of the leaves changes - they become translucent and watery. Over time, the plaque darkens and becomes dense, the shoots begin to rot, and the top of the bush withers.

The plant will have to be destroyed if most of the bush is infected with white rot. At the early stage of detection of fungal activity, the affected areas are removed. The knife must be disinfected. Sections are treated with activated carbon or colloidal sulfur. Every week it is recommended to treat the bushes three times with “Acrobat” or “Topaz”.

With gray rot, brown weeping spots appear on the leaves and on the watermelon itself, covered with a grayish or black coating. You can save plants with a mixture of copper sulfate and crushed chalk (1:2) or by spraying with Topaz, Sumilex, Teldor.

For reference. By planting calendula, marigolds or mustard greens around the melon, you can prevent fungal infections. These plants secrete phytoncides that have a detrimental effect on fungi.

Leaf rust

The causative agent is a parasitic rust fungus. It appears as brown tubercles on the bushes, which crack over time and rusty-colored fungal spores spill out of them. The shape and size of the tubercles may vary.

To cure the plant, infected shoots and sections of leaves are cut off, and the bushes are treated with fungicides. As a preventive measure, nitrogen fertilizers are minimized.

Olive spot

A fungal disease that affects all above-ground parts of the plant. In most cases, the berries suffer; gray-olive ulcers form on them, from which a cloudy liquid oozes.

If treatment is not done in a timely manner, the plant dies within 5-10 days. For disinfection, use “Kartotsid” or “Oxychom”. At an early stage, Bordeaux mixture is effective.

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Why do watermelons and tops turn black?

Blackened watermelon is not uncommon for domestic farmers. When growing melons, gardeners may encounter this problem due to unsuitable climatic conditions and, in particular, frost. Watermelons and tops begin to darken - if rescue measures are not taken, the harvest is lost.

If watermelons are grown in greenhouses, it is recommended to artificially heat the greenhouse. When growing melons and melons in an open field, you need to choose the right planting location and time. Damage to the ovaries can be avoided with good lighting and ventilation of the area, correct watering and enrichment of the soil with minerals, and compliance with the rules of crop rotation.

Infection with fungal diseases also explains why crops turn black. This is the main sign of the activity of fungal microorganisms. Anthracnose and fusarium are the most destructive to the crop.

Watermelon pests and their control

The melon crop is attacked not only by fungal diseases; significant damage to the crop is also caused by pests, of which there are also many.

Among them:

1. Melon aphid. It destroys flowers and ovaries, sucking out all the juices. To repel aphids, it is enough to use folk remedies - treat plants with infusions of onion, garlic, wormwood, and tobacco chips. Planting the perimeter of the bed with herbs is effective. If there are large numbers of insects, use insecticides.
2. Spider mite. Unopened flowers, ovaries, and shoot tips are covered with thin translucent threads, reminiscent of a cobweb. Insecticides are ineffective because they are not insects, but arachnids. Use acaricides: “Omite”, “Neoron”, “Apollo”.
3. Wireworm. Its activity is evidenced by through holes in the berries, which lead to their rotting. To combat the larvae, traps are installed in the ground - jars of potatoes or beets. Traps need to be changed several times a week, and any caught specimens must be destroyed. With strong activity, “Grom-2”, “Diazonin”, “Zemlin” will help.
4. Sprout fly. The larvae infect the seedlings, the second generation infects the adult plant. The harvest quickly rots. To combat them, insecticides are used and the soil and leaves are treated. Before planting, seeds are soaked in Fentiuram solution. After a few days, the planted plants are sprayed with Iskra Bio.
5. Thrips. They not only harm the plant, but also transmit dangerous diseases. They look like small black dots on watermelon leaves. It is recommended to use “Fitoverm”, “Karate”, “Vertimek” or “Spintor”. 3-4 treatments may be needed at intervals of 7-12 days. It is better to remove the affected parts of the plant immediately.

For reference. Folk remedies are effective only at the early stage of a pest invasion.

Preventive measures

Preventive measures are the most effective method of control, since pathogens remain viable for several years in the soil, on equipment, weeds and plant debris.

Main methods of prevention:

1. Use seeds of healthy fruits for sowing and disinfect them.
2. For sowing, choose easily ventilated, well-lit areas where pumpkin crops have not been grown over the past 3-4 years.
3. Loosen the soil regularly.
4. Feed plants with nutrients and microelements.
5. Maintain comfortable soil and air temperatures.
6. Do not touch the leaves when watering in the morning and evening with water heated to 22–25 °C.
7. Damaged or rotten fruits should not be stored with healthy berries.
8. In areas where crop disease has been noted, burn plant residues.
9. In the fall, the soil cleared of plants is dug up onto the bayonet of a shovel and the earthen clod is turned over.

Conclusion

Compliance with the rules of adequate care and prevention will help avoid the development of crop diseases. If difficulties arise with growing melons, modern treatment methods using fungicides, insecticides, acaricides and some folk remedies help.

The advanced stage of plant infection requires the destruction of diseased plantings.