Scab is a dangerous infectious plant disease caused by microscopic pathogenic fungi, actinomycetes and bacteria. It affects and deforms the surface of leaves, shoots, tubers and fruits, which greatly reduces the yield. Scab disease is widespread in temperate climates. There is scab of fruit trees and shrubs, as well as types of scab that attack potato and beet tubers.
Description of the disease
Pear scab disease only at first glance seems frivolous, but in fact this fungal disease weakens the fruit tree, as a result it slows down, the fruits spoil and fall off. The causative agent is a spore actinomycete,
developing in unharvested foliage. The capsules in which the spores overwinter burst under the influence of heat in the spring, and the scab spores are carried by the wind over long distances.
Photo of pear scab disease
Spore reproduction occurs more actively in a humid, warm environment. All fruit trees growing on the site are infected, not just pears. The danger comes from abandoned garden plots where no one cares for cultivated plants, so they can be sources of various diseases, including scab.
EXCELLENT VARIETIES OF PEARS!
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Need to know!
It is recommended to treat pears for scab in the spring before the sap begins to flow and in the autumn after the end of leaf fall.
It should be noted that the scab fungus that develops on pears does not affect apple trees and vice versa, but can affect other fruit trees.
This disease can appear unexpectedly on a weakened tree that is frozen in winter, or that bore fruit abundantly in the previous season.
The period of infection of a pear with scab and further spread of the disease lasts from 7 to 60 days.
What is scab and how to deal with it? - video
The main symptoms of scab are:
- the appearance of blackness on the foliage;
- the appearance of growths on shoots and fruits.
Fighting this disease can take a long time if symptoms are discovered late.
Reasons for development
There are factors that increase the likelihood of developing pathology. There is a high risk of pathology if:
- warm temperature within 20-26 degrees;
- rainy weather and high humidity levels;
- depletion of the tree as a result of cracks, breakages, lack of fertilizing;
- poor care.
The older the plant, the higher the likelihood of disease occurrence. The risk group also includes plantings that do not receive enough care. In this case, the plant’s protective functions are reduced. The planting is not able to resist pathogens.
Causes and symptoms of scab
The main symptoms of this disease are easy to determine.
The main signs of pear scab are:
- leaves and shoots burst, swellings and growths appear on them;
- the color of the foliage changes from green to dull olive, the characteristic shine disappears;
- pears and leaves quickly fall off and begin to rot;
- the bark and ripe fruits become covered with cracks and begin to peel off;
- In some fruits, the deformation appears initially; the scab is asymptomatic.
Photo of a sign of scab on a pear
After a latent period, this disease begins a new stage, in which spores actively reproduce on the underside of the leaves. Active formation of spores weakens the pear tree and disrupts water metabolism.
Need to know!
If you do not start fighting scab in a timely manner, then over the next seasons the pear tree will practically not bear fruit.
If rainy weather sets in during the flowering period, scab will certainly damage the flowers. If the symptoms of scab appear at the stage of ovary formation, then the foliage, bark and fruits that are beginning to develop will be damaged. If a gray coating and small spots of black color appear on the fruit, this indicates a severe damage to the tree; such fruits should not be eaten.
Pear scab, how to deal with it - video
The main causes of scab on pear trees:
- increased soil and environmental humidity;
- rotten leaves and fallen fruits remaining in the tree trunks from last season and not removed on time.
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Veles pear Chizhovskaya pear
If fruit trees are planted too close to each other, there is a high probability of the disease quickly spreading throughout the garden plot.
Some varieties have low resistance to growing in regions with rapidly changing weather.
Pears of the same variety are not planted side by side - if one fruit tree is affected by scab, the others will immediately become ill.
Apple and pear trees
The arrival of spring signals an attentive attitude towards trees. Having discovered colony spores with spots and a velvety brown or olive coating, they begin to immediately fight the scab, otherwise it will fill the entire tree. At the initial stages, garlic tincture with laundry soap or saline solution helps.
Stable temperature conditions up to +30 slow down the progression of the disease.
Defeat especially threatens the apple varieties “Grushovka Moskovskaya”, “Antonovka”, “Slavyanka”, “Borovinka”. Unsustainable pear species - “Bergamot mlievsky”, “Forest beauty”.
Today, breeders have developed hybrids that are resistant to the fungus, which should be chosen for breeding on the site. You can defeat scab on plants only with competent agricultural technology and the implementation of all the points described above.
Why is scab dangerous for pears?
When the fruits of pear trees are affected by scab, their productivity suffers - in this case, you cannot expect a rich pear harvest. And when growing these fruit trees on an industrial scale, this means that the pears will suffer greatly, and the harvest will be negligible. If fruits are affected by scab, they should not be eaten or stored.
If preventative treatment of pear trees against scab is not carried out on the garden plot, gardeners do not fight the disease at an early stage of its development, and as a result, they may lose most of their plantings. Pears can become sick for several years, stop bearing fruit and in many cases simply die.
Important!
To prevent the spread of scab disease in the garden, it is necessary to plant stone fruit trees (plums, peaches, apricots) next to the pear.
Signs
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The first signs of scab on a pear appear in the spring when the leaves bloom. Round brownish spots appear on the plates. Over time, they noticeably increase in size and darken. In the absence of control measures at this stage, the disease spreads to flowers. The affected buds do not form an ovary and fall off.
This fungal disease also negatively affects the taste of fruits.
Subsequently, the scab spreads to pear fruits. In this case, similar dark spots appear on their surface, which may look like warts. Subsequently, they merge into a single whole and form entire necrotic areas.
Scab causes fruits to grow small, irregularly shaped, and covered in cracks.
Important! Weakened and depleted pears are more susceptible to this fungal disease.
Disease control on pear trees
The first rule of any gardener is
to regularly check the fruit trees in the garden for disease or pest damage at the beginning of the spring season and throughout the summer.
When the first signs of scab appear, it is necessary to begin treatment of diseased pears and carry out preventive treatment of other fruit trees to eliminate the possibility of the disease spreading.
Most gardeners take measures to disinfect the garden in advance, before the scab appears, while others have to deal with the disease after it appears on the pear in the summer.
Currently, there are a large number of effective chemicals that can effectively combat the fungus that causes scab.
Scab. Treatment and prevention. Garden diseases - video
Features of the disease and pathogen
Scab is a common fungal disease that most often affects apple and pear trees. But the deviation may spread to other plants in the garden. The causative agent of the disease is Venturia pirina Aderh. This subspecies is typical for pears. Other plants are attacked by other fungi.
The main danger of the disease is the complete destruction of the crop.
Traditional methods of combating pear scab
- Dry mustard.
1 sachet of this substance is dissolved in a bucket of heated water. Treatment of pears with mustard solution against scab is carried out during flowering and mass formation of ovaries, during intensive ripening of fruits. - Salt.
1 kg of salt is dissolved in a bucket of water. You can treat pear trees with a saline solution against scab before flowering or after the ripe fruits have been fully harvested. This solution helps dry out moisture, which prevents the active spread of fungal spores. - Potassium permanganate.
Potassium permanganate is dissolved in a bucket of heated water to obtain a solution of medium concentration. Treatments of pears with potassium permanganate for scab are carried out in the evening hours. - Field horsetail.
A decoction of this plant should be prepared. To do this, the vegetative mass of the plant is crushed, poured with boiling water and infused for 48 hours. The decoction is poured into the trunk circles of the pear at the beginning of the spring period.
Important!
It is necessary to disinfect not only the tree itself, but also the trunk circle with a diameter of at least 2.5 m from the base of the tree.
Treatment times and basic rules
It is best to treat pear fruit trees for scab before the ovaries appear or after collecting ripe fruits in the fall. Any drugs actively fight the fungus for 12-14 days. It is recommended to carry out alternate treatments with fungicidal preparations and folk remedies. The timing of such treatments also depends on the weather conditions in the region where pear trees are grown.
Photo of the pear processing table
If after spraying it begins to rain, the moisture will wash away the preparations from the above-ground parts of the trees and will only contribute to the development of the disease.
In the central regions of Russia, spraying pears against scab is carried out from the first ten days of April to the first ten days of June, in the south - in early spring or late autumn.
In hot weather, trees are not treated. When the disease is detected late, they begin the fight with gentle means at any time.
First you need to remove all damaged and dried shoots. And if the pear is severely damaged, you can do without pruning and spray immediately.
After the effect of the scab drug wears off, it is necessary to apply organic fertilizers to the tree trunk circles after watering, simultaneously with loosening the soil.
It is not recommended to treat trees too often.
Where does the scab fungus overwinter?
The scab fungus overwinters depending on its shape. Thus, the marsupial form is sown from leaf litter (overwintered infected leaves), and the conidial form is preserved in the form of a mycelium, which is well preserved in the bark of infected shoots. After the mycelium has reached the desired size, the shoot bark breaks and it spreads throughout the area with the help of wind and rain.
The fungus may also persist in affected fruits; it is important to carry out hygienic cleaning of the garden in the fall. To prevent the persistence of the pathogen in winter and a new spread, the garden is also sprayed with fungicidal agents in the fall, and this is done more than once in rainy autumn.
When to treat pears for scab
You can use the following scheme for treating pears for scab:
- first spraying - treatment of pear trees with copper sulfate for scab in the spring, before the buds swell;
- spraying the pear with any fungicidal preparation suitable for it (for example, Horus, Topsin-M) during the formation of flower buds;
- then the pear should be treated against scab for the third time (with a fungicidal agent) - this is carried out after the trees have finished flowering;
- after 2 weeks, spraying with fungicide is repeated again;
- The last treatment of pears for scab occurs at the end of summer - beginning of autumn, after harvest.
Such measures to treat pear scab should be carried out in case of severe damage to trees by the disease.
Resistant varieties
Resistant pear varieties are much less susceptible to scab and other fungal diseases.
If such climatic conditions are constantly present in the region, special varieties of pear trees that are resistant to scab should be bred:
- Lada;
- Clapp's favorite;
- Marble;
- Bere Bosc and Moskovskaya;
- Memory of Zhegalov;
- Autumn Susova;
- Muscovite;
- Severyanka;
- Chizhovskaya.
Preventive measures for pear scab
It is important to properly care for your garden and prevent the occurrence of scab. Mature fruit trees should be regularly inspected at the beginning of the spring and autumn in order to detect symptoms of the disease in time.
The following rules must be followed to eliminate the possibility of scab on the pear:
- plant these trees in places well lit by sunlight;
- maintain a distance of 3 m between identical pear varieties;
- do not grow fruit trees too close to each other, regularly prune the trees, removing branches growing inside the crown and contributing to its thickening;
- the sections must be disinfected with a weak solution of potassium permanganate and covered with garden varnish;
- tree trunk circles must be kept clean; weeds, fallen fruits and leaves must be constantly removed;
- In the spring and autumn periods, sanitary pruning of pear trees is carried out.
Need to know!
Preventive treatments are useless if the pear is already affected by scab.
INTERESTING!
Pruning an apple tree in autumn
Disease prevention
You can prevent pear scab damage if you follow simple preventive measures. They cannot completely eliminate the likelihood of developing the disease, but they can reduce the risks to a minimum.
Prevention measures:
- Plant trees in sunny, open areas.
- Avoid overcrowding of plantings.
- After fruiting, promptly remove fallen rotting fruits.
- It is necessary to promptly treat wounds and cracks in the bark with garden varnish.
- Whitewash the trunk and skeletal branches.
- In late autumn, collect and burn all fallen leaves.
It is extremely important to clean the crown of broken and damaged branches every year.
