Verticillary Wilt Of Tomato

2024 Author: Gavin MacAdam | [email protected]. Last modified: 2023-12-16 13:38

Verticillium wilt can affect a fairly wide range of crops, and tomatoes are no exception in this case. Since the fungus-pathogen penetrates into the vascular system of growing crops, the growing tomatoes begin to wither gradually. Initially, verticillary wilting manifests itself on the lower leaves, therefore it is extremely important to timely identify the ailment and take all measures to eliminate it

A few words about the disease

Among the first main symptoms of tomato damage with this ailment, one can note the formation of characteristic V-shaped ulcerations on the lower sides of the leaf blades, as well as fan-like yellowing tapering to the edges of the leaves. Leaf veins turn brown as the attacking verticillary wilting develops, and a little later necrotic specks can be seen on the leaves. Often, these spots are confused with the symptoms of some other diseases, for example, with signs of alternaria. The difference is that with verticillary wilt, concentric rings are absent on the necrotic spots. Sometimes verticillary wilting is also confused with fusarium and a number of other equally unpleasant ailments.

As a rule, daytime wilting is noted when the fruits have already begun to set. Initially, during the hottest part of the day, infected plants will begin to wilt slightly. Subsequently, wilting leaves often die off and fall off. Some time later, the symptoms of verticillary wilting also cover the shoots, as a result of which the plants are no longer able to reach their usual sizes. In this case, only the leaves in the upper part remain green. Fruits on infected plants are formed with yellowed tops and are relatively small in size. Moreover, they often burn in the sun due to the rather low density of the leaf covers.

To a large extent, the development of verticillary wilting is favored by a rather low air temperature. Temperatures in the range of 20 - 24 degrees are considered especially suitable for the propagation of harmful fungi. Often this disease can be encountered on alkaline, slightly alkaline and neutral soils, but on acidic podzols it is quite rare.

The causative agent of this scourge is a fungus called Verticillium albo-atrum, which makes its way into vegetation through root hairs. And the spread of mushroom hyphae occurs along the conductive system of the xylem, as a result of which it is heavily clogged and deprived of the full movement of mineral nutrients and water. Moreover, this dangerous fungus secretes a toxin that provokes the formation of spotting on the leaves, followed by their wilting.

For several seasons, the harmful fungus is able to persist in the soil in the form of microsclerotia - tiny black formations. And in moist soils, the development of this fungus occurs at a truly lightning speed.

How to fight

The use of resistant varieties, as well as maintaining crop rotation, are the best preventive measures against destructive verticillary wilting. No less important is strict adherence to basic agricultural techniques and rules. The soil must be well drained and moisture maintained at an optimal level. And when cultivating especially expensive crops, soil fumigation will also be a justified measure.

Among the varieties resistant to verticillium wilt, such varieties as Santiago F1, Erato F1, Chibli F1 and a number of others can be distinguished. A hidden seed infection can be eliminated by warming or dressing the seeds.

When growing tomatoes, you should try to prevent the soil from overheating above 28 degrees. Watering, as well as top dressing, should be very moderate. On hot days, it is unacceptable to water tomatoes with cold water. And after each watering, it is recommended to loosen the soil around the plants to a depth of ten to fifteen centimeters. Mulching near growing crops also gives a good effect.