Hemm verticillosisimsejħa wkoll tracheoverticillosis, is a fungal disease that affects horticultural, fruit tree and ornamental crops. It is caused by a fungus called Verticilliumascomycete of the family Plectosphaerellaceae. If not properly controlled, this pathology causes severe damage to plants, ranging from partial desiccation to death. Fortunately, however, the problem can be prevented with adequate agronomic techniques and with the use of organic products.
So let’s see which crops are affected by verticillosis, the symptoms to recognize the disease on plants and the biological defense strategies.
What plants affects verticillosis
The fungi responsible for verticillosis are mainly two: Verticillium dahliae u Verticillium albo-atrum. These are highly polyphagous fungi, that is, capable of attacking numerous crops. Those of greatest agricultural interest are: solanaceae (brunġiel, tadam, patata u bżar ħelu); the cucurbits (zuchini, qara u ħjar); there frawli; the stone fruit (ħawħ, għanbaqar, Siġra taċ-ċirasa, berquq, siġra tal-lewż); L’siġar ta ' u l- ħajja.
Symptoms and damage of verticillium to vegetables
The verticillosis on vegetable plants initially manifests itself with a suffering aspect of the aerial part. Withering is in zones and begins with the oldest basal leaves. The verticillosis on the eggplant is very evident, with areas of the leaves that appear discolored and limp. As a rule, it is easy for the disease to evolve quickly and to spread to the rest of the vegetation, resulting in wilting and desiccation. If the attack is early, that is, shortly after the transplant, the affected area has difficulty developing.
To be sure that we are faced with verticillosis it is necessary to dissect the stem of the affected plant and note if there is a strong browning of the internal tissues, which is due to the occlusion of the lymphatic vessels. In rare cases, the plants do not completely succumb to verticillosis, but in any case they remain dwarf and will lead to few and low-quality fruits to ripen.
Verticillosis of the olive tree
Among the tree crops, the one most susceptible to verticillosis is the olive tree. The Verticillium it first affects the root system, then goes up along the vessels of the xylem and goes towards the ramifications, obstructing the lymphatic channels.
The consequence is the drying up of branches or even entire branches.
In the olive tree, the course of the disease can be very slow, the first serious damage is noticed many years after the appearance of the fungus. Also in this case it is advisable to dissect the affected branches and see if there is browning of the internal tissues.
On young olive trees (5-15 years old) this fungus is able to cause the total wilting of the vegetation, therefore the death of the plant, within 1-3 years from the appearance of the first serious symptoms.
Verticillium life cycle
IL Verticillium they are very feared fungal pathogens in agriculture, as they are able to be preserved in the environment for a long time. Conservation takes place on the residues of infected vegetation or in active form on spontaneous herbaceous plants. The spread can also occur using infected nursery material or through the simple contact between parts of sick plants and healthy plants.
Penetration occurs passively, especially in correspondence with wounds or on organs in contact with the ground, where the pathogenic conditions of the fungus remain excellent for long periods. Furthermore, in the soil, the pathogens responsible for verticillosis are also preserved in the form of microsclerotia.
How to prevent verticillosis
Agronomic prevention of verticillosis consists of cultivation practices aimed at reducing the spread of the disease. First of all, you have to carry out adequate crop rotationsavoiding planting crops of the same familja botanika always in the same parcel of land. In the event of an attack, the destruction of infected plant residues is very important, where possible by fire (law 3 May 2019, n. 37 article 20).
Finally, you have to pay attention to seedlings selected in the nurserysince, in case of bad nursery management, the chances of infection are very high.
Biological products against verticillosis
Attacks of verticillosis can be prevented, with good efficacy, by inoculating the soil mikorize. These are nothing more than fungi already present in nature, able to establish a symbiotic relationship with the roots of plants and, therefore, protect them from harmful fungi, such as the Verticillium.
Trichoderma
Among the different species of mycorrhizae, the most effective in the control of verticillosis are those of the genus Trichoderma. These have been used for many years in organic farming for the control of fungal diseases (downy mildew, fusarium spp, sclerotinia spp), so it’s relatively simple find them in specialized shops.
Trichoderma reinvigorates the root system of crops, creates competition with harmful pathogens, stimulates and improves the natural defenses of plants and improves the rhizosphere, increasing the presence of useful microorganisms.
It can also be used both on annual and perennial crops (olive groves, orchards), even if it is on the latter that it carries out its protective action against verticillosis to the maximum.
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