How to get rid of scab on apple trees

Scab is the scourge of apple culture. Many varieties of apple trees resistant to this disease have been obtained. However, they do not always meet the requirements of the consumer. Often it is necessary to grow old varieties of apple trees that are loved by many generations. And they are usually very susceptible to scab. We will help the gardener deal with this problem.

Scab on the leaves of the apple tree - characteristics and causes

Scab is a long-known disease of apple trees. Even before the 19th century, they knew about her, but she did not bring many problems. In the scientific literature, the first mention of it dates back to 1819, when the causative agent of scab - the fungus Venturia inaequalis - was first described. Somewhere from the middle of the last century, the disease began to spread and bring noticeable damage in industrial gardens with a high density of tree plantings that have the same genotype.

The causative agent hibernates on fallen leaves and fruits in the stage of pseudothecia (immature fruiting bodies). With the beginning of the growth of young shoots, the spore of the fungus disperses. The most dangerous periods for infection are swelling of the buds, staining of the buds, flowering and mass decay of the petals. Due to the presence of the mucous membrane, spores are attached to the underside of the leaves of the apple tree and, in the presence of sufficient moisture, germinate in the outer layer of the skin of the leaves and young shoots. The next stage - conidial - occurs in two to three weeks, when the fungus that has passed into conidia - motionless spores of asexual reproduction - infects the leaves of the crown again. A temperature of +18 ° C to +20 ° C is the most favorable for this process. Well at this time, the appearance on the leaves, ovaries, tips of young shoots of spots of light olive color, which brown when they grow brown, crack.

The first symptom of scab is the appearance on the leaves of spots of light olive color, which, upon growth, turn brown, crack

Due to the defeat, the leaves and ovaries fall, and the fungus continues its development on them, laying, already known to us, pseudothecia, which will winter there until next spring. The cycle is closed. In summer, the scab forms cracked skin, seals and firm, necrotic, brown-brown spots on the fruits. Apples become deformed, small - their growth stops.

In summer, on the fruits of the scab forms skin cracks, seals and hard, necrotic, brown-brown spots

Scab is common in regions characterized by rainy summers - the northwestern regions and the North Caucasus region. In hot and arid areas, scab is much less common.

How to get rid of scab on apple trees

Fighting with scab requires a systematic approach. There are several general recommendations, following which you can protect the apple orchard from this problem:

• Planting and growing scab-resistant apple trees. When choosing an apple tree variety that is immune to scab, you need to know that it may not be immune to other fungi. The following varieties can be recommended for areas of the Middle Strip:
  • Summer:
    • Orlovim;
    • Orlinka;
    • Desired.
  • Autumn:
    • Sun;
    • Zoryanka;
    • Oryol pioneer.
  • Winter:
    • Pepin Oryol;
    • Freshness;
    • Imant;
    • Kulikovskoe and others.
• Avoiding thickened landings. Recommended intervals for the particular variety should be observed. They can be from 0.8-1.2 meters for dwarf apple trees and up to 5-6 meters in the case of tall trees.
• Exclude planting of apple trees in shaded and wetlands.

And besides this, in areas with a high risk of scab mentioned above, regularly carry out the necessary preventive measures.

One of the most that was hit by scab is Honey Gold, for all 5 points. That is, visually visible on apples (especially leaves). I have another misfortune - powdery mildew. They were not ready for it - Br. Golden, Bel. Sweet, Pam. Lipunov, Pam. Ulyanischev. It is excellent both in scab and powdery mildew, i.e., the immune system is completely Imant (!!!), Williams Pride, Topaz.

yri, Bryansk region

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Step-by-step instructions for spring actions to combat scab

It is spring preventive and sanitary measures that are most important in the fight against this harmful fungus. They begin to them even before the onset of sap flow and swelling of the kidneys.

1. If the fallen leaves and fruits remained in the fall, then they are collected and destroyed.
2. In the crown of the apple tree, the presence of fallen mummified fruits is also possible - they should be removed and destroyed.
3. Carry out regulatory trimming of the crown by removing branches, thickening the crown.
4. Before the onset of sap flow, it is necessary to conduct treatment with potent pesticides:
   • Once every three years, use DNOC;
   • In other years, they use Nitrafen.
     

     Before the onset of sap flow, it is necessary to conduct treatment with potent pesticides

5. Before flowering, apple trees are treated with one of the fungicides (drugs to combat fungal diseases):
   • Chorus;
   • Speed;
   • Abiga Peak and others
6. After flowering, a second treatment is carried out with the selected preparation.

Step-by-step instructions on summer activities to combat scab

In the summer, they mainly monitor the development of the plant and, if necessary, take emergency measures. They may be needed if leaves and / or fruits affected by scab are noticed. In this case, the actions of the gardener are as follows:

1. Carefully inspect the tree. Discovered fruits, leaves and shoots affected by scab are removed and destroyed.
2. Spray the crown with the Strobi preparation. The treatment is repeated 2-3 times with an interval of 7-10 days.
3. After that, they begin treatment with Fitosporin-M biofungicide with an interval of two weeks, which do not stop until the fruit is harvested.
   

   Phytosporin is not addictive

4. Simultaneously with this treatment, whey treatment can be used. It is believed that lactic acid bacteria feed on the fungus Venturia inaequalis and dramatically reduce its presence.
   

   Whey is also used to combat scab.

5. Regularly clean the garden of weeds.

Step-by-step instructions for autumn actions to combat scab

Autumn preventative measures are the most important in the fight against scab and other diseases, as well as pests.

1. After leaf fall, you need to collect all the fallen leaves, weeds and destroy them. Usually they are burned, and ash is subsequently used as fertilizer. Do the same with the mummified fruits remaining on the apple tree.
   

   After leaf fall, you need to collect all the fallen leaves

2. After the sap flow is completed, the apple tree is sanitized by removing dry, diseased and damaged shoots. They are also burned with leaves.
3. The bark is cleaned from roughnesses in which spores of the fungus can winter, using a wire brush.
4. Deeply dig the soil of the trunk circles.
5. The soil and crown of the tree are sprayed with a 3% solution of copper sulfate or Bordeaux fluid.
6. The trunk and thick branches are whitened with a solution of slaked lime with the addition of 1% copper sulfate and PVA glue.
   

   The trunk and thick branches are bleached with lime mortar

Essential anti-scab drugs

To combat scab, as with other fungal diseases, fungicides are used. When working with them you need to know some features:

• Mushrooms develop immunity to specific drugs and after three times of use, usually the effectiveness drops to zero.
• You need to pay attention to the active substance of the drug - often the same substances appear under different names and brands.
• Preparations have different waiting times until the permitted time of eating fruits. Before harvesting, you need to use drugs with minimal waiting times.

Table: apple scab fungicides

Photo gallery: apple scab fungicides

The use of saltpeter to combat scab

It is believed that treatment with ammonia or potassium nitrate copes with scab no worse than treatment with fungicides. In this case, the tree is fertilized with nitrogen at the same time. For prevention, spraying with a 0.5-3% solution of nitrate is used in early spring and (or) late autumn. For the treatment of the disease, the concentration is increased to 10%.

Ammonium nitrate can be used to combat scab

Summarizing, I want to express my opinion based on personal experience. I’ll clarify, my orchard is located in the east of Ukraine. We got it two years ago in a rather poor condition. Including some apples and pears were sick with scab. The first thing we started with is cleaning the garden, intensifying thinning of thickened crowns. I had to do it in stages, since there were too many unnecessary branches. I am a proponent of prevention, and try not to bring to treatment. Therefore, the collection and burning of fallen leaves, digging around tree trunks, whitewashing trees, installing hunting belts - I never miss these events. I try not to abuse the treatments. Be sure to spray the crowns of apple trees and pears with a 5% solution of iron sulfate in late autumn. I believe that this not only contributes to the prevention of fungal diseases (including scab), but also eliminates iron deficiency in plants. And my father taught me from childhood that iron for apple trees is the main element. In early spring, be sure to apply copper sulfate and Nitrafen. Now is the middle of April - Horus treatment is planned tomorrow - this is my favorite antifungal drug at this time of the year. Another drug that I regularly use throughout the season and for all plants is Fitosporin-M. This is an effective biological preparation and I do not use any other without urgent need. In emergency cases, when an infection occurs, I use Strobi. I can say that in two years I got rid of scab and other ailments in the garden.

Gardeners reviews about the problem

I managed to get rid of the scab on the pear (the infection was strong) during a one-time treatment with Bordeaux mixture in the early spring before budding. And do not forget the fellow countryman around. Of course, a lot depends on the size of the apple tree, whether you can sprinkle it all the way to the top of the head. I had to do this from a stepladder. And do not forget about safety measures, so as not to sprinkle yourself - the muck is still that. After processing the traces of scab, it’s been six or seven years.

Vitat Moscow

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In addition to antifungal drugs, clarification of the crown and clearing of bushes around the tree help in order to have more sun and air, in short, hygiene measures :)

erdel Saint Petersburg

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A very good result in the fight against scab, fruit rot and the small size of apples gives a strong lightening of the crown with cutting a large number of branches to every second. When I bought the garden, the branches spread almost to the ground, the old owner had not been pruning for five years. The apples were small with scab. After a good pruning (and how much firewood for a barbecue!), The next year the apples became large and without scab. It was harder with apple trees planted among the buildings. In the frosty years they winter well, but fruit rot strongly resists. I had to once again radically cut them and at the same time the neighboring apple trees by agreement (I have a chainsaw). There is more air and light. I hope for a good result this year.

Rulaman Kazan

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Every spring and autumn I process with vitriol no less than 5%, in the places of processing the scab has disappeared. And of course, pruning, greatly brightens the crown at the end of winter. One of my favorite activities. I couldn’t completely get rid of the scab, it remains at the height where I can’t get it, but overall I like the result. Apples have become larger, less rot.

Eva3712 Moscow

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Video: how to deal with scab on the apple tree

Of course, scab is an unpleasant apple tree disease. But, using modern drugs, as well as regularly performing the necessary preventive and treatment measures, the gardener can cope with the problem.