Scab: what to process, preparations, how to fight on an apple tree, pear
Scab is an infectious disease that poses a great danger to many crops. The causative agents of this disease are pathogenic microscopic fungi, bacteria and actinomycetes. A plant affected by scab shows a deformation of the surface of leaf blades, tubers, stems and fruits, which is extremely negative for crop yields. The most widespread such disease is observed in temperate climates. There is a scab due to which shrubs and trees suffer, and there are also types of such a disease that can affect beet and potato root crops.
Features of the disease
Experts have noticed that all cultures are affected by various causative agents of scab. For example, the scab on an apple tree will never spread to potatoes or pears. However, all types of such a disease have common symptoms. When examining a sick plant, the following symptoms of the disease can be detected: the skin begins to peel off, pustules, specks, warts and ulcers form on the fruits, tubers, shoots, leaf plates, stems and flowers. If the plant is affected by scab very strongly, then drying and leaflet flying around, violation of the water balance of the crop are observed, and this very poorly affects the fruiting of both the current and future season. Also, sick flowers and buds fly around, and the fruits become ugly due to this disease. In addition, during storage, such fruits begin to rot, as it is very easy for rot pathogens to penetrate them through cracks formed on the surface of the peel due to scab.
Culture is affected by such an infectious disease only under certain conditions. For example, increased soil moisture. This disease cannot develop without moisture. The fungus is activated when the snow falls in spring, while the air temperature should be about 12 degrees. Over the summer, the scab begins to develop if it often rains or there are frequent fogs and dews. And the development of the disease contributes to overly thickened planting. In those garden plots where many trees of one species grow, a rapid spread of the disease is noted especially if the surface of the soil between the rows is overgrown with weeds, along which spores from one plant to another are transmitted along the bridge. Also, the rapid spread of scab in the garden is also observed with genetic uniformity, for example, when trees of the same species grow nearby. For example, if a plum or a pear is planted near an apple tree affected by scab, then they are unlikely to “get infected” from the apple tree with such a disease. And if another 2-3 apple trees grow near a diseased apple tree, then all these plants will be affected by scab after some time. Also, some plants are more often affected by scab due to susceptibility of the variety. So, experts found that some varieties are less likely to get scab, while others are more likely (due to their high susceptibility). To date, breeders have managed to obtain varieties that are highly resistant to scab.
Scab. How to deal with scab on the apple tree.
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How to treat scab
Chemicals deal with scab most quickly and effectively. And in some cases, pesticides are the only hope for saving a sick plant. For the treatment of trees, fungicidal preparations are used, such as: But, Skor, Bordeaux mixture, Hom, Fitosporin, etc.
In order to get rid of scab, it will take several treatments, and it is extremely important to choose the right time for spraying the plants. And to do this, you need to know at what time the beginning and end of the spread of ascospores of the fungus falls.The first time the plants are sprayed from this disease in the phase of the green cone, repeatedly - in the phase of the pink cone and the last most important treatment is carried out after the petals have flown around. In the summer, cultures from this disease are treated with an interval of 15–20 days. If the season turned out to be rainy, because of which the level of humidity regularly increases, then the plants will have to be sprayed from scab at least 5 or 6 times.
Many gardeners have seen in their own experience that it is much easier to prevent the development of scab by regularly taking preventive measures than to fight the disease later.
There are certain agricultural techniques that are very effective in combating scab. For example:
- It is necessary to clean the surface of the soil under the trees and shrubs from the foliage in time, and also dig the soil in near-stem circles.
- In order to notice the onset of the development of the disease in a timely manner, frequent and regular inspections of the trees should be carried out during the growing season. Fruits and foliage that look suspicious are immediately ripped off and destroyed.
- Do not forget to thin out the crowns of shrubs and trees every year, since when they thicken, the development of scab occurs very quickly.
- Plants are recommended to be fed on foliage, using fertilizers based on phosphorus, potassium carbonate and silicon, for example: Opty Sil and Solfan PK.
- When fall leaves end, shrubs, trees, and also the soil surface under them are sprayed with a solution of urea (7%), ammonium nitrate (10%) or Nitroammofoski (10%). When spraying plants with these drugs, the air temperature should be at least 4 degrees. Thanks to this treatment, not only will most of the pathogenic microbes and pests be destroyed, but also bushes and trees will receive additional nutrition.
Scab in the trees
Apple tree scab
Apple trees are most often affected by scab. Initially, foliage scab develops: on the front surface of the affected leaf plates, spots of olive color form, which covers a velvety coating containing fungal spores. As the disease develops, foliage flies around. Later, fruit damage is observed: spots of brown color are formed on their surface with a lighter border, on which a velvety coating appears. This plaque disappears over time, and under it you can find cork tissue. Then there is an increase and cracking of such cork spots, and often they are connected to each other. The shape of the affected fruit becomes irregular and ugly, and they themselves are very poorly stored.
The following apple varieties are most susceptible to scab damage: Moscow Grushovka, Slavyanka, Borovinka, Antonovka, Papirovka and Belfler-Chinese. The most resistant to the disease are considered such varieties as: Pepin saffron, Jonathan, Chinese anise, Rodnichok, Union, Fortune, Juno, Dawn, Fairy, Red amber, Golden summer, Lyubava, Vasilisa, Orpheus, Margot, Nocturne, Talida, Ekaterinodar and other
To cure a sick apple tree, it is necessary to combine agrotechnical measures with spraying trees with special pesticides. The diseased stems found on the plant are sure to be cut out, and also make sure that the trunk circle is always clean, for this, remove and destroy the surrounding fruits and foliage in a timely manner and remove weeds. In autumn, a mandatory digging of the trunk circle is carried out. Thinning and sanitary pruning of trees is carried out in early spring.
For the prevention of scab, apple trees are sprayed shortly before the sap flow begins; for this, a solution of Nitrafen emulsion (per 1 liter of water 20 grams) or DNOC (per 1 liter of water 10 grams) is used.The first spraying of the apple tree for medicinal purposes is carried out in the green cone phase with a solution of Bordeaux mixture (1%), and the second time the tree is treated in the pink bud phase, for this use the Skor solution (2 milligrams per bucket of water). If you did not have time to spray the plant on sleeping buds with Nitrafen or DNOC in a timely manner, then it is recommended to spray the solution with a Bordeaux mixture in the green cone phase (3-4%), and if you wish, the treatment in the pink bud phase can be omitted in this case. Then, apple trees are sprayed from the scab regularly with a break of 15–20 days; for this, alternatives such as Tsineb or Kaptan are used in the form of an emulsion (per 1 liter of water 5 g), Khom (per 1 liter of water 4 g) and colloidal sulfur in the form of a suspension (per 1 liter of water 10 g). When at least 30 days remain before harvesting, it is necessary to stop all spraying with pesticides. In those years when there is a massive lesion of scab apple trees, after harvesting, the plants are sprayed 1 more time using Tsineba solution (0.5%) or Bordeaux mixture (1%).
Scab on apple and pear. It’s never too late to start a fight.
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Scab on a pear
The signs of pear scab damage are almost the same as the symptoms of apple tree damage (see above). However, in a pear on foliage, spots form on the lower surface, and in addition to fruits and leaf plates, young shoots are also affected by such a disease. The scab pathogen overwinters on tree branches, as well as on the leafy foliage under the plant.
15–20 days after opening the kidneys, the first symptoms of scab appear. In the event that the tree was struck by the disease early (in spring or in the first summer weeks), then the spots that appear on the foliage and fruits will be large. And if the tree was infected with scab later, then the spots will be smaller. The late appearance of scab is observed when the weather is wet before harvesting. In this case, the spots that appear are very small, and they are almost invisible, but during storage they will certainly appear. These fruits are called "warehouse pear." A lot of very small vesicles appear on the diseased stems on the cortex, while their surface becomes rough and begins to peel off.
The most susceptible to scab damage are pear varieties such as: Forest Beauty, Bergamot Mliyevsky, Sapezhanka and Ligel Bere winter. The following varieties are relatively resistant to this disease: Bere Hardy, Bere Ardanpon, Bere Bosch, Mliyevskaya Autumn, Favorite of Klapp, Vrodlyva, Vyzhnitsa, Etude, Trembita, Zolotovorotskaya, Stryiskia, etc.
In order to cure trees affected by scab, it is necessary to promptly clean the surface of the soil beneath them from flying leaves and fruits. In spring, they carry out mandatory pruning to thin out the crown and remove all diseased and dried branches that are destroyed by fire. In autumn, the area is cleaned of flying leaves and fruits, which are also burned. In order to destroy the causative agents of the disease that winter in the soil of the near-trunk circle and in the bark of the plant, in the fall and at the beginning of the spring, the ground under a pear is dug up, and the tree and soil under it are sprayed with a solution of Nitrafen (3%) or DNOC (1%). To process one hundred parts, you will need 2 buckets of mortar. In spring, the first treatment, called "blue" spraying, diseased with scab pears is carried out in the green cone phase, for this use a solution of Bordeaux mixture (3%). Then the plant is sprayed in the pink bud phase and at the end of flowering, for this they take the solution of the drug Skor (2 grams per bucket of water). When 1.5–2 weeks have passed from the time of foliage coarsening and again after 20 days, the pears are sprayed with a solution of one of the following agents: Khom, Kaptan, Skor, Tsineb, colloidal sulfur and other similar drugs.
Peach and apricot
Stone fruit scabs are less likely to be affected than pome crops, but this disease is still dangerous for them. With increased humidity against a background of moderate air temperature, the likelihood of damage to apricot and peach by scab increases. With an increase in air temperature to 30 degrees, the disease begins to develop much more slowly.
The first symptoms of scab on the fruits of apricot and peach are specks with a fuzzy outline of a greenish-brown color. Over time, darkening and proliferation of spots are observed, a velvet coating of black or olive shade appears on their surface, while their borders become more clear. If the plant is very affected, then the spots connect to each other and form a crust. There is a slowdown in fruit growth, ulcers and cracks form on their surface, through which pathogens of fruit rot can penetrate. Often, affected fruits fly around. In patients with stems, there is a lag in development, and on the lower surface of the affected foliage there are many vague spots of greenish or brown color. The most susceptible to scab are apricot varieties such as: Krasnoshchekiy, Shalakh and the whole “pineapple” group.
To spray trees on sleeping buds for the purpose of prevention, use a solution of Bordeaux mixture (3-4%) or other means containing copper. Directly from the scab, the plant is sprayed in the first decade of June, and for this they use Skor, Horus or Kaptan (strictly follow the instructions on the package). After 15 days, repeated spraying is carried out. Later treatments will not give the expected effect, however, after the foliage spreads around the apricot in autumn, it can be sprayed with a solution of Bordeaux mixture (1%). Fungicidal preparations containing copper are most effective in fighting scab on apricot. And in order to protect the plant from this disease, one should not forget about the rules of agricultural technology of this culture.
Damage to the plum tree scab occurs under the same conditions as in the case of other stone fruits, the same symptoms of the disease also appear. In this regard, it is necessary to treat plum in the same way as apricot:
- the first time the plant is treated in spring on sleeping buds ("blue spraying");
- in the first ten days of June, treatment with Horus or Skor solution is carried out, after 15 days, repeated spraying is necessary;
- when all the leaves fly around the plant in the fall, it is treated with a Bordeaux mixture (1%).
Like other stone fruits, cherries are relatively rarely ill with scab. But if, nevertheless, the plant is affected by this disease, then it is not the scab itself that will harm it most, but the causative agents of various rot, which easily penetrate the cracks in the fruits formed due to the disease. In this regard, in order not to lose crop and protect cherries from the disease, one should not neglect the preventive treatments that begin to be carried out in early spring with the same means and on the same principle as in the case of apricot.
Citrus crops can also be affected by scab, but oranges, lemons and tangerines are not grown in the middle latitudes by gardeners on their garden plot. Cherry plum, quince, peach and cherry can also get sick with scab, and you can cope with the disease in the same ways and at the same time as in the case of a pear, apple and apricot. Do not forget about preventive measures, which are almost the same for all garden trees.
Treatment from scab shrubs
Gooseberries are also affected by scab. However, the symptoms of this disease on such a shrub are often confused by gardeners with signs of powdery mildew, but these are completely different diseases. That is why, before proceeding with the treatment of the bush, try to compare all the available signs of the disease to be sure that it is scab.
So that the plant does not get sick with scab, do not forget to regularly carry out preventive spring treatment on buds that are not yet swollen. For this procedure, a urea solution (7%) is used, and pay attention to the fact that after spraying, the branches and buds, and the soil surface under the plant should be well moistened with the product. When leaf fall in autumn is over, the ground near the gooseberry is cleaned of flying foliage and digging around the trunk circle and re-spraying with urea solution.
If the bush was still affected by scab, then it is sprayed on the swollen buds with a mixture of agents such as Horus and Aktara or with a solution of Bordeaux mixture (2-3%). After 30 days, Aktara and Horus are sprayed again.
Compared with gooseberries, currants are affected less often by scab. However, experts do not advise taking risks and recommend taking all necessary preventive measures. Since gooseberries and currants are related cultures, the same methods and drugs are used to combat scab. But in this case, before proceeding with the treatment, you should definitely make sure that the plant definitely hurts with scab, and not powdery mildew.
Scab on potatoes
Potatoes can also be affected by scab, like fruit trees. In this case, the surface of the tubers most often suffers, because of which they become ugly, and the seed qualities and taste of such potatoes deteriorate greatly. At the same time, affected root crops cannot be stored for a long time. If the potato is very affected, then you can not use it for food.
Those areas on which bushes affected by scab grew, it is highly recommended not to use for growing potatoes for 4 or 5 years (no less). This culture can be affected by the following types of scab: ordinary, tuberous (oosporosis), black (rhizoctonia), silver and powdery. In more detail about each of types:
- Common scab. On the surface of the tubers are formed not very deep small sores that have an irregular shape. Over time, an increase in the spots occurs, they connect with each other, and a cork formation appears on their surface. If you dig up a diseased potato, then on its surface you can see a cobwebbed raid, but as soon as the tubers dry, it disappears.
- Powdery scab. It appears if the causative agents of the disease get into the roots, tubers and stolons through mechanical damage or eyes. On the surface of the roots, galls are formed, which are irregularly shaped growths of white color, which become darker with the development of the disease. And a lot of warty pustules appear on the tuber, which eventually become ulcers with a dusty brownish mass. During storage, diseased potatoes are often affected by dry rot or late blight.
- Silver scab. It is possible to understand that potatoes are ill during harvesting of tubers or during storage. Slightly distinguishable opaque spots of various size and shape of a brownish tint are formed on diseased tubers. Actively, the disease begins to develop closer to spring. At this time, the affected tissue on the tuber acquires a metallic luster, and it looks slightly depressed inward. If the potato is very sick, then it loses a large amount of moisture, due to which the peel becomes wrinkled.
- Lumpy scab (oosporosis). The defeat of tubers occurs in the earth, during their active growth, but to understand that they are sick, you can only in the repository. Round pustules appear on potatoes, which are painted in the same shade as the peel. These pustules are convex, depressed or flat. Over time, they increase and form areas that are outwardly similar to late blight, but in this case there is no rot under the skin.
- Black scab (rhizoctonia). This type of scab that infects potatoes is the most dangerous. Because of it, the gardener can lose up to 20 percent of the crop. Because of this disease, tubers die, twisting of the apical leaf plates is observed, mold appears on the basal parts of the bush. And also because of it, the stems of the bush can rot and die.
In order to prevent the defeat of potatoes by this disease, you need to plant only a completely healthy planting material, which is of high quality. Just before planting, do not forget to treat the tubers with a solution of Rovral, Fito Plus or Aquaflo. The introduction of manganese, boron and copper into the soil can help reduce the likelihood of damaging the plant with scab. It is also very important in order to prevent such a dangerous disease not to forget about the rules of crop rotation. So, on the site it is recommended to grow potatoes and plants belonging to the legume family one by one. And in the event that you can’t plant potatoes every year in a new area, be sure to refuse to introduce fresh manure into the soil.
Alkaline soil in the area is recommended to be acidified with a solution of ammonium sulfate (2 tbsp. Per bucket of water). With this solution, the land on the site is shed during the flowering period of the bushes, and 1 liter of the mixture is consumed per plant. When about 15 days are left before harvesting, it is recommended that the tops be mowed, so that the peel on the tubers will become stronger. During the formation of buds, spray the bushes with Zircon solution, this will not only stop the development of scab, but will also increase the yield. After 15–20 days, the plants are treated with Fito Plus (3 sachets of water 1 sachet), due to this, the degree of tuber affection with scab will decrease. And experts advise that you choose for cultivation those varieties that are most resistant to scab, for example: Aspia, Skoroplodny, Alpha, Lady Rosetta, Mentor, Nicolas, Prevalent, Patrons, Element, Polyana, Yavir, Vesta, Dara, Racurs, Tiras , Riviera, Favorite, Reserve, Spring, Herald, Varmas, Ramensky, Vilna, Vyatka, Early Zhukovsky, Bezhitsky, Bryansk novelty, etc.
TT8 scab on potatoes. fungal diseases
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In order to cure a plant affected by scab, fungicidal preparations belonging to the 3-4 hazard class are used, since they are not able to form stable compounds, penetrate the skin or accumulate inside the fruit. Which tool to choose in a particular case depends on various factors and on the personal preference of the summer resident. However most often, drugs such as: Chorus, Skor, Rayek, Strobi, Abiga-Peak, Phytoflavin, Bordeaux liquid and vitriol.
PROCESSING AN APPLE FROM SCARP BIOLOGICALS
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