Fighting bacterial diseases in vegetables

Bacterial diseases are threatening the vegetables of Tyumen gardeners, all because of elevated air temperatures and high soil moisture. It is important to recognize the threat and start treatment in time — otherwise you can lose a significant part of your harvest. Agronomists from the Tyumen branch of the Federal State Budgetary Institution Rosselkhoztsentr (Russian Agricultural Center) explained what these diseases are and how to fight them.

“Bacterial diseases of vegetable crops are one of the most insidious problems a gardener can face. Unlike fungal infections, bacterioses develop rapidly, often unnoticed in the early stages, and can destroy a significant part of the harvest in just a few days,” the specialists explain.

Tomatoes

Tomatoes are affected by several types of bacterial infection. The most dangerous is bacterial canker. The disease shows up during flowering: the edges of the leaves turn yellow and curl, and brown sores with yellow slime form on the stems and fruit stalks. White spots appear on the fruit, which over time turn yellow and crack. The bacterium attacks the plant«s vascular system, causing wilting even before external symptoms appear.

Cucumbers and cucurbit crops

Bacteriosis of cucumbers (also called angular leaf spot) is one of the most common diseases of cucurbit crops — cucumbers, zucchini, pumpkins, melons and watermelons.

Oily, angular grayish or brown spots appear on the leaves between the veins; in wet weather the spots become oily, and when they dry out the tissue cracks and crumbles. Sores form on the fruit, which become crooked and misshapen; with early infection, necrosis develops on the fruit, leading to deformation.

The disease spreads especially actively in greenhouses at high humidity and temperatures from +25 to +30 degrees Celsius (+77 to +86 degrees Fahrenheit). The risk of disease increases many times over with sharp temperature swings.

Cabbage

Vascular bacteriosis attacks, as the name suggests, the vascular system of cabbage. Characteristic black rings of vascular bundles are visible on a cut head. The disease leads to the death of young plants, underdeveloped heads and poorer harvest quality.

Potatoes

Potatoes suffer from blackleg of the stems, ring rot and brown slimy bacteriosis. These diseases are characterized by wide prevalence and high harmfulness. Bacterial wilting manifests itself in blockage of the vessels, which restricts the flow of water to the upper parts of the plant.

Signs of bacterial damage:

Watery spots on the leaves that darken over time and often have a yellow border;

Wilting of the leaves and the whole plant — one of the most alarming signals;

Cracks on the stems and exudate oozing from the cut;

Darkening of the vascular bundles on a cut stem or root crop;

Softening and rotting of the fruit, often accompanied by an unpleasant odor.

Agronomists say the key condition for successfully fighting bacterioses is regularly inspecting the plants.

How to fight bacterioses

The specialists do not advise using chemical preparations, because after applying them you have to wait 20 days before harvesting. As an alternative, they name biological products that can be used even shortly before harvest:

Fitosporin-M — based on hay bacillus. For cucumbers, three sprayings are recommended: the first as a preventive measure, then at intervals of 10–15 days.

Alirin-B and Gamair — biological products based on Bacillus subtilis strains with long-lasting preventive and curative action.

When the first diseased plants are found, foliar treatments must be stopped. Reduce watering to lower humidity. Agronomists warn that affected plants that cannot be treated must be removed and destroyed, and the soil disinfected.

If your vegetables grow in a greenhouse, maintain the optimal temperature: from +22 to +25 degrees Celsius (+72 to +77 degrees Fahrenheit). Keep the optimal humidity: from 80 to 85 percent. Ventilate regularly, and disinfect greenhouses and hotbeds.

“Bacterioses of vegetable crops are a serious threat to the harvest, but with the right approach they can and must be fought. The main principles of protection are a comprehensive approach that includes prevention, timely diagnosis and competent use of protective products,” the Tyumen agronomists concluded.

Earlier we published recommendations on how to save a harvest of tomatoes. Because of torrential rains, they are threatened by various diseases.

Before that, we explained how to prevent rot on peppers.