General description of the disease
Typically, this fungal disease initially affects the deciduous mass, and from there it migrates to the tree bark.
Diseased greens become covered with a light ivory-colored coating. This color indicates that the apple tree is seriously ill. Only stone fruit trees are susceptible to infection. Wild plantings are not affected by the milky shine. This disease is spread over very wide areas. Shine is found on apple trees:
- southern regions of the Russian Federation;
- in Crimea;
- in the North Caucasus;
- in Ukraine.
The disease can actively develop within 3 years. At this time, every year air cavities form under the skin of the leaves, which cause the appearance of the characteristic color.
Downy mildew (Peronosporosis)
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Downy mildew or downy mildew is a type of powdery mildew. It begins in the same way - with brown spots, which then take on a gray or purple color and enlarge, become denser and at the last stage become brown. The affected part (leaf, flower) quickly deteriorates and falls off.
Apple downy mildew
Important!
Downy mildew develops most actively at a temperature of +18...+29 degrees and a humidity of 60-80%.
To combat the disease, the drug “Kurzat”, “Ordan”, “Baksis”, “Bordeaux mixture”, “Copper oxychloride” is used. Treatment of apple trees against disease is carried out once a week. Folk remedies include a solution of potassium permanganate, 1% colloidal sulfur, and a soap-soda solution (40 g of soap and 50 g of soda per bucket of water). Suitable in this case, if the disease is not advanced, is iodine milk (10-12 drops of 5% iodine per liter of skim milk).
Causes of infection of apple trees
There are 2 forms of this dangerous disease. Gardeners distinguish between non-parasitic milky shine, caused by unfavorable environmental conditions, and parasitic, which is usually caused by the fungus S. purpureum (Pers) Fr.
Non-parasitic milky sheen
Signs of infection are noticeable immediately - they look like a silvery coating on all the leaves of the apple tree. The detection of the disease most often occurs in the middle of the summer season: late July - early August. The reasons for the development of the lesion are:
- freezing of trees in winter;
- sudden changes in temperature during the day;
- nutritional deficiency;
- lack of moisture;
- lack of drainage in the soil;
- strong lighting.
The leaves on the southern side of the crown are the first to suffer, then the plaque spreads throughout the entire tree. A characteristic metallic sheen appears along the edge of the sheet plate, and then covers the entire available area. The interior of the green mass and the wood are usually not modified: there is absolutely no necrosis, peeling or peeling. The disease has a focal path of spread; it covers very large areas. Measures taken in a timely manner help to avoid serious consequences.
False milky shine can be cured by observing all agrotechnical measures and creating favorable living conditions for the apple tree.
Parasitic milky sheen
The causative agent of the parasitic form of milky shine is a fungus that releases toxic toxins into the wood tissue.
In this case, infection appears in early spring, when silvery spots appear on newly blossoming foliage. By the middle of the summer season, the green plates become brown, curl and dry out. Often you can see a kind of peeling of the skin on them, which looks like small bubbles. In this case, the wood begins to suffer: brown spots of varying intensity are found on the cut.
Identification of such signs signals that it is time to take urgent measures.
Otherwise, the percentage of infected trees in the garden will begin to increase steadily. At the initial stage of development of the disease, apple trees fight it on their own, but then the milky sheen passes into the skeletal branches and young shoots. The peeling of the bark begins, severe gum formation opens, and numerous bodies of fungal infection form in the affected areas. They spread throughout the tree, germinating in cracks in the bark, forming mycelium.
Next, a layering of fungal bodies occurs, which, in turn, leads to a characteristic transformation of the disease, which has the appearance of roofing tiles. The pathogen begins to penetrate the wood fibers, poisoning the tree with toxins from the root system to the top of the crown.
Within 3 years, the fungus takes over the plant completely, the apple tree dries out and dies.
detailed information
Plants affected by the disease
In recent years, especially after harsh winters, gardeners are often faced with a dangerous disease, which is usually called milky shine. The disease affects all fruit and berry plants, with the exception of garden dugouts, but is especially dangerous for cherries, plums and other stone fruits.
Manifestations of the disease
First, young unfolding leaves on individual branches acquire a silver-gray color with a metallic sheen. Why? The skin of the leaf blade lags behind the internal tissues. Air penetrates into the resulting voids, reflecting rather than absorbing sunlight, causing a silvery sheen. In addition, along the edges and along the main vein of such leaves, the tissues become dead. Gradually, the “silvery” covers more and more new branches, and then the entire tree. Leaves and fruits become smaller, thin out, wither and dry out. As a result, the plant dies. Signs of milky shine appear in spring, but become most noticeable by mid-summer. The plant tries to fight the disease, as a result of which in its initial stage the symptoms on the branches may disappear for a year or two, but under unfavorable conditions they reappear, and the disease flares up with renewed vigor. The bark of the affected branches, and then the trunk, first becomes covered with spots, and then completely becomes dark brown, peeling off in long stripes. Dirty white or gray caps appear on its surface - the fruiting bodies of the fungus that causes the disease (Chondrostereum purpureum). They are semicircular in shape, flat, with wavy edges, up to 5 cm wide. A reddish-purple layer is formed on their lower side, where spores develop - the infectious beginning of the fungus. The caps are layered on top of each other like tiles and can encircle entire sections of the trunk or branches. The fungus develops in wood, along its fibers, penetrating into water-conducting vessels. but not in leaves or non-lignified growths. It poisons the leaves with waste products - toxins coming from the sap from the wood, which leads to the separation of the skin of the leaf blade. The fungus can penetrate plants only through fresh, unhealed wounds, especially those covered with moisture. These can be cuts after pruning, broken branches, hail and frost damage. Fungal spores are carried by the wind from neighboring still living and cut down fruit or forest trees (most often poplars). The infection is also transmitted with undisinfected pruning tools after pruning diseased trees, when grafting with lignified cuttings, or when roots grow together between neighboring plants. Very often the disease enters gardens with infected seedlings. The initial development of the milky sheen is hidden, “smoldering” in nature, and signs of damage on the leaves and bark appear after the fungus has done significant destructive work in the wood.
Parasite activity period
The parasite is most active during the dormant period of trees. Any sudden weakening of the plant can cause a real outbreak of the “sleeping” milky shine. This is caused, in particular, by freezing of trees, severe winter or spring pruning, overgrafting, overfertilization with nitrogen fertilizer, and excessive development of leaf apparatus. Plants "wither", become infertile and usually die after a few years. Often, detection of the disease is hindered by a false “non-contagious” milky sheen that affects only the leaves, where, along with the “silver” zones, there are stripes of healthy green tissue along the veins. Bark and wood are not affected. This happens when there is a lack of boron or stagnation of water in the soil, severe damage to leaves by spider mites, or excessive sunlight on trees in the southern steppe regions. When these causes are eliminated, trees and shrubs recover.
How to prevent infection?
Infectious milky sheen, however, cannot be cured. Although the factors that trigger the disease are beyond the control of the gardener, infection can be prevented. Any pruning should be carried out only in dry weather and the sections should be immediately disinfected by covering, or better yet, spraying with white water-dispersion paint (polyvinyl acetate, acrylic), for example BC-511. Add 20 g of copper oxychloride to 1 liter of paint. We can also use the biological drug trichodermin. It is better to remove broken branches and, in any case, cover the cut with paint or spray it with fungicides. The putty should be held firmly and not crack. Garden pitch is not suitable for this. If the cuts cannot be disinfected, it is better not to prune the trees. You should not hesitate to cut out and burn branches and trees with “silver leaves”, patches of peeling bark, or mushroom caps on the surface. The branches are cut down to healthy, light-colored wood, leaving no stumps of diseased, browned tissue. Stumps, if they cannot be uprooted immediately, are cut as close to the soil as possible and covered with paint. In the garden, diseased trees should be pruned as a last resort; knives and pruners should be disinfected from fungal infection by wiping them with a sponge soaked in denatured alcohol, butyl alcohol, chloramine, or, at worst, a solution of potassium permanganate (2 g per 1 liter of water). Pruning wounds should have a flat, smooth, not “crumpled” surface. You should not prune diseased trees and shrubs during the dormant period until flowering or the beginning of active growth. Cherries and plums are pruned immediately after harvest, apple trees after flowering. If possible, it is advisable to avoid the proximity of the garden to poplars - breeding grounds not only for the milky sheen, but also for other infections.
Symptoms of the disease
The initial stage of development of the milky sheen is called smoldering.
Often it occurs in a hidden form, which makes it difficult to notice the impending danger in time. Novice gardeners underestimate the insidiousness of the disease and begin to take action only when the pathogen has already affected most of the trees in the garden. The first obvious manifestation of shine is a change in foliage color. It acquires a whitish tint with a slight metallic sheen. Branches affected by the fungus gradually dry out completely. The harvest on them, accordingly, does not ripen and falls ahead of time.
Moniliosis (monilial burn, fruit rot)
The surface of the affected fruit becomes covered with brownish spots, which gradually increase in size. Later, white concentric circles with convex fungal spores appear on them. The affected fruit falls off or remains hanging on the tree and becomes mummified.
To prevent infection in early spring, spray trees with copper-containing preparations (for example, 3% Bordeaux mixture, Abiga-Peak, Oksikhom (according to instructions), or others. At least 2 liters of solution must be used per tree during each treatment.
3-4 days before the start of flowering, the apple tree needs to be sprayed again with Bordeaux mixture, but with a 1% solution. Instead of this drug, you can also use Fitolavin. If you notice carrion, spraying must be repeated.
A month before harvesting, carry out preventative spraying of the garden. Use Fitosporin-M or iodine solution (dilute 10 ml of the drug in 10 liters of water and spray the trees evenly). Repeat spraying after 3 days.
In the fall, after harvesting, the affected apple trees need to be treated with a solution of copper sulfate (100 g of copper sulfate per 10 liters of water), using 2 liters of solution for each tree.
Principles of treatment of milky luster
The main step in the fight against this insidious disease is timely diagnosis. Next, the form of infection should be identified. With a false milky sheen, it will be enough to provide the apple trees with proper care and comfortable living conditions:
- timely application of potassium-phosphorus fertilizers;
- debugging the irrigation schedule;
- regular loosening of the soil.
Spring mulching of the soil can give good results.
If the disease is caused by a fungal infection, then treatment measures should be more drastic. In the early stages it is necessary:
- cut out and burn affected areas of wood and crown;
- remove the bark with mycelium caps;
- cut young shoots to the healthy part;
- clean surfaces;
- Wash the sections with a previously prepared 4% solution of copper sulfate.
All broken branches should be removed and exposed areas should be disinfected. To do this you need to use:
- garden var;
- water emulsion;
- oil paint;
- plasticine.
All garden tools must be sharpened and disinfected.
If the disease affects the entire tree, any control methods will be useless. In this case, you should completely remove the plant from the garden plot. You can't even leave the root system. Otherwise, the disease will spread to neighboring plantings.
If the apple tree suddenly turns silver, this indicates that it has been affected by a false milky sheen. It can appear on a tree after severe cold weather. The disease is characterized not only by its rapid spread, but also by its sudden disappearance after a couple of years, provided that the fruit trees are properly cared for.
Prevention measures
There are no chemicals to combat milky shine. The best way to avoid disease is prevention.
To exclude the disease, follow simple recommendations:
- Protects the plant from freezing. To do this, the space around the tree is mulched.
- Do not plant seedlings in wet and low-lying areas.
- For frost resistance, they are fed with potassium and phosphorus fertilizer.
- Apple trees are watered at the beginning of the growing season, and at the end, watering is completely stopped.
- Dead branches are removed. The cut is disinfected and covered with garden varnish.
- At the beginning and end of the season, apple trees are sprayed with a solution of iron sulfate.
- For planting, seedlings intended for a specific area are selected.
- Whitewashing is carried out. To do this, add 2 kilograms of lime and half a kilogram of copper sulfate to 10 liters of water.
- At the end of autumn they feed with wood ash.
- Periodically spray with onion infusion.
How to deal with a dangerous fungus
An integrated approach to treatment and timely preventive procedures are the main measures that will prevent infection from occurring in the garden.
Treatment
First you need to identify the form of the disease. With a false milky sheen, it will be enough to provide the trees with good care and comfortable conditions:
- application of potash and phosphorus fertilizers;
- normalization of irrigation;
- loosening the soil.
Spring mulching of the soil around the plantings has a good effect. Plum grows poorly and often suffers from frost in low-lying, heavily moist areas.
On a note! The requirements of the plum to the soil are determined by the type of rootstock, since the general condition of the tree depends on its root system.
Therefore, they select areas that are well-lit by the sun, with moderately moist soils and no nearby groundwater.
