Fusarium wilt of cucumbers: causes and treatment methods

Fusarium wilt of cucumbers is a common condition caused by infection of the plant's vascular system. The disease can quickly kill infected plants and spread to healthy ones. To prevent such a tragic outcome, it's important to understand the causes, symptoms, treatment, and prevention methods.

What is Fusarium wilt of cucumbers?

The primary causative agent of Fusarium wilt, or fusarium, is a pathogenic fungus of the genus Physarium. Its spores spread through the soil via wind and water. The microorganism is resistant to low temperatures, so it remains viable during the winter. It remains active for 3-4 years.

The disease is characterized by rapid spread. Infection occurs through the vegetable's root system. The pathogen penetrates the vascular system, disrupting the water-conducting tissue. It also releases toxins, which also negatively impact the plant. This results in gradual tissue death, followed by wilting and death. The disease can affect the plant at any stage of the growing season. However, the pathogen most often becomes active during fruit formation, a time when vegetables are particularly weakened.

Reasons for development

Failure to follow agricultural practices is the main reason for pathogenic microorganisms to enter a garden plot. The fungus is transmitted through contaminated soil, seedlings, seeds, and weeds. Water from a reservoir used for watering the plants is often a carrier. The risk of infection increases severalfold if the seed, soil, and greenhouse are not disinfected before planting.

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The following predisposing factors contribute to the further spread of infection:

• increased soil acidity;
• overheating of the culture (critical temperature – +35°);
• sharp changes in night and day temperatures;
• lack of nutrients in the soil;
• abundant watering with very cold water;
• high humidity in the greenhouse;
• invasion insect pests;
• excess nitrogen in the soil;
• microtraumas of vegetable crop roots.

Temperatures from 18° to 26°, soil moisture over 75% are the conditions under which fungal spores begin to actively multiply.

Characteristic signs of infection

Characteristic symptoms of Fusarium wilt are difficult to detect on young plantings. Signs of the disease can be seen on mature plants. These include:

• signs of root and basal rot appear on the seedlings (the lower part of the crop darkens, the root becomes thinner);
• wilting of the lower leaves, yellow spots gradually appear on all leaf blades;
• leaf deformation – edges turn yellow, dry out, curl;
• the cucumber flower stalk slows down its growth and curls up;
• the ovary turns yellow and then dies;
• fruiting decreases or is absent altogether;
• The diseased crop produces cucumbers with a bitter taste.

If left untreated, the disease progresses, spreading to all parts of the plant. Complete wilting of the crop leads to its death. If the seeds were already infected, the sprouted seedlings will rot and experience reduced germination.

What are the dangers of infection for vegetables?

Many gardeners believe that fusarium wilt poses no threat to cucumbers. However, this is far from true. If the disease is not recognized and treated promptly, the crop's growth is stunted. As a result, fruit buds fail to form, which impacts yield.

Treatment of Fusarium wilt of cucumber

Fusarium wilt on cucumbers can be controlled using a variety of methods. Control methods are selected based on the severity of the infestation.

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Biological agents

These medications are safe for humans and the environment, but are often ineffective in severe cases. Therefore, they are used early in the disease's development and for prevention. The following popular biopharmaceuticals can be used to successfully treat the disease:

• Trichodermin;
• Baktofit;
• Vitaros;
• Fitosporin – M.

These products contain substances that destroy the primary pathogen and halt the progression of the disease. Treatment should be carried out strictly according to the instructions on the packaging. Biological products should not be used concurrently with chemical fungicides.

Chemicals

The pathogen is highly resistant to chemical treatments. Therefore, the effect of such treatments may be minimal. Systemic treatments containing benzimidazole and its derivatives are considered the most effective. The most suitable treatments for fusarium wilt on cucumbers include:

• Fundazol;
• Topsin – M;
• Quadris;
• Benomyl;
• Fundazim;
• Gliocladin;
• Arbotrin.

The listed preparations are applied only by irrigation. To increase the vegetable's resistance to wilting, it is recommended to treat the seeds and seedlings with these chemicals before planting.

Folk methods

To combat the disease, you can use the following folk remedies:

1. Milk solution. To prepare, you'll need 200 ml of milk, 50 g of grated laundry soap, and 30 drops of iodine. Apply the prepared solution to the plant stems.
2. Garlic infusion. Crushed garlic (50 g) is diluted in a liter of water. The mixture is left for 24 hours. Then, 9 liters of water are added to the infusion. The resulting mixture is sprayed on the plants.
3. A whey solution. For every 10 liters of water, you'll need 4 liters of whey. Use for spraying vegetables and watering the soil.
4. Onion peel remedy. Use 4 cups of onion peel per bucket of water. Simmer the mixture over a flame for 50 minutes. Spray the plants with the cool mixture.
5. Wood ash is an effective remedy. The ash is applied to the soil surface and all parts of the plant.

Preventive measures

To prevent the occurrence and spread of fusarium and verticillium wilt, first and foremost, it's important to follow preventative measures. These include:

1. Carefully select seeds for planting. Buy seeds only from trusted sellers. If necessary, disinfect them with fungicides.
2. Crop rotation rules must be observed. Cucumbers should not be planted in the same plot of land for several years in a row.
3. Prepare the soil and greenhouse in the fall. The greenhouse structure is thoroughly disinfected with copper sulfate. Biopreparations or nitrogen-containing fertilizers are added to the soil. The soil is subjected to deep cultivation.
4. Monitor soil acidity. If the pH is above 7, apply dolomite flour or wood ash in the fall.
5. Regularly inspect crops for disease. If diseased crops are discovered, they are destroyed (burned).
6. Follow proper care instructions. Water the plant regularly, weed and loosen the soil, and eliminate harmful insects.
7. In addition, you must not forget to apply fertilizers and harvest the fruits in a timely manner.

Varieties resistant to fusarium

If there were cases of pathogen activity in the area last season, it's best to select fusarium-resistant seeds for sowing next year. The following hybrid cucumber varieties have increased immunity to the disease:

• Rowanberry;
• Dunyasha;
• Raphael;
• Vocals;
• Knight;
• Sir;
• Zhukovsky;
• Ob;
• Caprice;
• Hector;
• Bunny, etc.

There are many methods for combating Fusarium wilt in cucumbers. Timely application of protective measures will help preserve the quality and quantity of the harvest. To prevent the fungus from appearing in your garden and the disease from affecting your vegetable crop, it's important to follow preventative measures. Strong, healthy plants can resist the "invasion" of this fungal disease.