Cytosporosis - Drying Out Of Fruit Crops

2024 Author: Sebastian Paterson | [email protected]. Last modified: 2023-12-16 13:47

Threat to the garden

Along with the well-known disease of moniliosis to gardeners, fruit pome and stone fruit crops suffer from the fungal disease of cytosporosis, the harmfulness of which is often underestimated. The pathogen infects shoots, semi-skeletal branches, stems (very rarely roots and fruits), causing them to dry out.

External symptoms of mycosis are manifested in the form of dying off of the cambium bark and wood. Often, this disease is difficult to recognize at the initial stage, which is expressed only in a slight change in the color of the color of the bark. Later, when its defeat becomes obvious - there is a strong discoloration, deformation and indentation of tissues - most of the tissues of the tree are infected. In a young tree, this bark condition usually leads to its death. The defeat of the bark of branches and shoots usually begins in places of mechanical damage, sunburn, frostbites, on strongly frozen shoots or branches. Strongly weakened trees are especially affected by cytosporosis.

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According to experts, the disease can develop in two forms: fulminant and chronic. In the first case, when the bark is affected in the forks of skeletal branches, whole branches often die within 1.5-2 months, which leads to the early death of the tree. In the initial phase of mycosis, red-brown or yellow-brown spots of irregular shape appear on the bark. Gradually increasing in size, they merge and ring the entire branch, which then dries up. Cracks often form on the border of the diseased and healthy tissue. Mycosis develops with maximum intensity in spring, early summer and autumn.

In the chronic form of the disease, individual parts of the cortex die off, its development takes on a sluggish character. Diseased trees can dry out in spring before bud break. If this phenomenon occurs during flowering, the blossoming buds curl, turn brown, dry up and hang for a long time on the dried branches. The leaves of such plants are smaller, slightly chlorotic (with a yellowish tint). After the death of a diseased tree, the root collar can remain healthy; shoots usually begin to actively form there.

The fungus overwinters in the form of pycnidia on dried parts of plants. Plants become infected with conidia in early spring or fall. The development of cytosporosis occurs in a wide temperature range (10 … 30 ° C) and at a relative humidity of 60-95%. Under natural conditions, especially on mature fruit-bearing trees, the joint development of pathogens of black cancer and cytosporosis often occurs, sometimes they are confused, since the signs of damage to their branches by pathogens are similar. However, unlike lesions by black cancer, the bark does not turn black during the development of cytosporosis, but remains reddish-brown and is hardly separated from the wood (it is wetted). On the dying bark, large, clearly distinguishable fruiting bodies of the fungus are formed in the form of tubercles, which makes the bark resemble goose bumps. Small spores of the fungus are formed inside these fruiting bodies.

Cytosporosis of fruit crops is widespread in our country and causes significant damage to orchards. Leaves affected by cytosporosis fall prematurely, and the shoots deprived of leaves do not have time to prepare for winter, as a result of which the yield sharply decreases, its quality deteriorates, and often the disease of the tree ends with its death.

The complex of the main protective measures that increase the winter hardiness of trees and their resistance to cytosporosis include: pruning of young fruit-bearing trees, removal and destruction of damaged branches, loosening the soil, timely fertilization, the use of disease-resistant varieties, phytosanitary measures (including chemical treatments) aimed at reducing the stock of infection. Whitewashing boles and thick branches in early spring with lime (2 kg / 10 l of water) with the addition of 100 g of copper sulphate previously dissolved in water and 20 g of diluted wood glue will favor better preservation of the bark of trees suffering from sunburn during this period of the year.

When treating deeply damaged boles and branches, wounds are cleaned to wood with a knife or chisel. Moreover, not only the affected bark is cleaned, but also 1.5-2 cm of healthy tissue adjacent to it. With a weak lesion, the section of the branch with the diseased bark is cleaned to healthy tissues, since in the warm season, with sufficient air humidity, the mycelium of the pathogen can spread over the surface at a distance of more than 10 cm from the affected area. The cleaned area is disinfected with a 3% solution of copper sulfate, after which it is covered with garden varnish or painted over with ocher on pure drying oil.

On large wounds, experts recommend applying a putty consisting of a mixture of clay and fresh mullein (in a 1: 1 ratio), and then tying it with burlap. Reducing the harmfulness of cytosporosis on fruit trees is facilitated by treatment with solutions of preparations containing copper (Bordeaux mixture, abiga-peak), recommended against moniliosis.

Spraying is carried out in the following terms: before flowering, during the isolation of buds; immediately after flowering; 15-20 days after the previous spraying; after harvest.