Verticillin wilt - symptoms, prevention and control
Verticillin wilt is a very serious fungal disease. The fungus that causes this dangerous disease is quite insidious, it can be in the soil for a long period of time and not cause any harm to plants, but at some point it can suddenly begin to attack the crop, which often leads to the complete death of the plant organism. In this publication, we consider the main symptoms of plant damage by this disease and methods for the prevention and control of verticillin wilt.
- How does verticillum wilt infection occur?
- Symptoms of Verticillus Wilt
- Fighting Verticillin Wilt
- Walt Prevention
How does verticillum wilt infection occur?
Verticillin wilt, also called “wilt,” causes a fungus belonging to the genus Verticillium. Typically, plants become infected with this dangerous fungus through the ground. At the initial stage of its development, the disease negatively affects the young shoots of the plant, which are not able to resist the disease, therefore they usually die first.
The plants that have various damages on the root system or in the lower part of the stem are most affected by verticillic wilting. These damages can be caused both by pests living in the soil, and by the person himself. For example, when digging a seedling from a nursery or when transplanting a plant to another place, when planting seedlings, improper (excessively deep) tillage, or excessively active work with soil near the trunk.
It is interesting that the fungus that causes verticillum wilting can live in the soil for up to ten, and sometimes more, years, so if the disease has manifested itself, then this area is best kept for at least a couple of years under black vapor. In addition, the fungus can live for a long period of time in plant debris, including the remains of plants infected with it, therefore, such plants must be removed from the site and burned outside its territory, preventing the parts of plants affected by the fungus from entering the soil layer.
After the fungus penetrates the root system or the lower part of the stem, it begins to actively spread through numerous xylem bundles along with an upward flow of water and dissolved nutrients throughout the plant. If the soil is infected with this fungus, then even seedlings that have barely appeared on the surface of the soil can die quite quickly, having previously twisted like a spiral.
The fungus most actively develops on soils that are excessively moistened (under the condition of excessive watering of the soil or in areas with close standing of the groundwater), as well as in years with excess natural moisture falling out in the form of rain or fog.
Also favorable periods for the development of the fungus are seasons with sharp changes in day and night temperatures. In addition, in neglected areas where plants are affected by pests, the fungus also develops very actively.
As for temperature, the fungus that causes verticillar wilting is especially active, develops at a temperature of 16 to 21 degrees above zero. If the temperature drops below 16 degrees Celsius, then the fungus may stop developing, during this period you can notice the formation of new shoots in plants, which, when warming, can be infected by the fungus quite quickly.
The fungus that causes verticillum wilting is also dangerous because it can attack a wide variety of plants, both vegetable and fruit, berry and ornamental. Quite often you can see signs of verticillaceous wilting on apricot, grapes, tomato, roses, chrysanthemums, lilacs, phlox, strawberries and a whole series of very different plants.
Symptoms of Verticillus Wilt
The deceit of the fungus and the danger of this fungal disease lies not only in the fact that the fungus can be in the soil for a long period of time, both before and after infection of the plants, but also in the fact that symptoms of infection, especially on perennial plants, are often observed one or even two seasons after infection has occurred.
Usually, the presence of verticillous wilting on plants can be noticed only after the shoots begin to die. The death of shoots does not occur simultaneously, while the plant as a whole may look good and even bear fruit, other branches can completely dry out in the same period of time.
Leaf blades on dying shoots first begin to dry at the edges, marginal necrosis forms, and then the leaves completely dry and fall off much earlier. This leads to a disruption in the photosynthetic apparatus and negatively affects the plant as a whole, including weakening its immunity, reducing winter hardiness (if it is a perennial plant).
Usually, first of all, the leaf blades located in the lower tier begin to turn yellow and die, gradually the disease kills all the leaf blades located on the infected branch. If the plant is severely affected by verticillum wilt, then often only its upper part remains alive.
With severe infection, drying and falling of the ovaries or fruits to a different degree of maturity is also observed, which depends on the time of infection and the rate of development of the fungus in the plant.
Sometimes it is possible to determine whether a plant is infected with verticillous wilting by cutting the shoot. A strong darkening of the tissues is sometimes noticeable on the cut, but, unfortunately, such obvious signs do not always appear.
Fighting Verticillin Wilt
It is extremely difficult to cure plants infected with verticillum wilt and to destroy the fungus in the soil. In the case of the onset of conditions that are very unfavorable for the life of the fungus, it can form sclerotia, form mycelium, even when at rest. With the formation of sclerotia, the fungus can live in the soil for several seasons, even if extremely unfavorable conditions for its existence are created.
Of course, the sooner you identify the disease and the faster you start to fight it, the higher the chances of ridding the plant body of this ailment. Otherwise, the fungus can develop in the soil and actively spread, infecting an increasing number of various plants grown on the site.
The first step in the fight against verticillar wilting can be multiple (4-5 times) treatment with copper-containing preparations or fungicides approved for use. In the case of fungicides, it is better to start with biological preparations, such as, for example, Gliocladin, which is an analogue of Trichodermin. It is good because it has a contact and systemic effect, is not addictive in the fungus, restores the microflora of the soil and even removes the toxicity of the soil after the use of other chemicals.
“Phytosporin-M, P” belongs to biological fungicides, this drug can also be used to disinfect seed material, because often a fungus that causes verticillous wilting enters the soil, and then into plants with seeds infected with it.
Of the chemical fungicides, the drug Maxim KS fights well with verticillic wilting; this drug is used to combat fungus in the soil and to disinfect seed material and bulbs of flowering plants.
Unfortunately, these drugs and many others do not always cope with verticillin wilt. If no effect is observed, then it is necessary to remove the plant from the site, treat the place where it grew with copper-containing preparations and not plant this type of plant in this area for at least five years.
Of course, it’s much easier than fighting to prevent the appearance of a fungus that causes verticillum wilt in your area. To do this, you must follow a number of important, but simple rules for growing plants.
The first rule is the observance of crop rotation and crop rotation. So, if we are talking about perennial crops (for example, apricot), then they should be planted in the same place after the uprooting of the site no earlier than five years later. If we are talking about annual vegetable or flower crops, then they should be planted on the site after three or four years.
After harvesting or at the end of flowering in the case of annual plants, all plant residues must be removed from the site. On perennial woody crops or berry bushes, the entire crop must be harvested completely; diseased and rotten fruits should also be removed from the branches and burned outside the site. In years with high soil and air humidity, which are characterized by sharp temperature changes, it is also necessary to remove all leaf litter and burn it outside the site.
Another important but fairly simple precautionary measure is to try to prevent strong drying of the soil on the site. Soil moisture must be maintained constantly at a normal level, that is, it must be prevented from drying out or waterlogging, and if excessive waterlogging is observed due to heavy rainfall, it is necessary to loosen the soil more often (every 2-3 days) to allow moisture to evaporate better.
When watering, it is important to use water at room temperature, but it is impossible to water the plants with cold and ice water from a hose, contrary to a common misconception this will not lead to hardening of plants, but can cause stress and a decrease in their immunity.
Apply sufficient fertilizer to the soil, do not abuse nitrogen, and do not allow plants to be deficient in phosphorus and potassium fertilizers. So that fertilizers are absorbed by plants as fully as possible, the soil must be acid neutral, if it is acidic, then dolomite flour or lime must be added to it.
As a preventive measure for verticillosis wilt, it is advisable to treat the soil and seeds, as well as the root system of seedlings with natural fungicides. So, infusions and decoctions of tobacco leaves, chamomile plants, as well as infusions of wood ash, soot and charcoal have a fungicidal effect.
In conclusion, some secrets of experienced gardeners and gardeners. It is noted that the fungus does not develop or does not appear at all, on sandy, well-drained soils with a neutral reaction of the environment. It has also been recorded that many weeds also suffer from verticillin wilt, so weeds must be fought and try not to cover their vegetative mass in the soil, especially in areas where the risk of the disease is high.