Scab on apple and pear: how to deal with the disease and prevent its development

Scab of agricultural plants is a dangerous disease, the causative agents of which can be both microscopic pathogenic fungi and bacteria. Scab affects the plant surface tissues and spreads quickly throughout the area, unless measures are taken in time.

This disease affects many plants - more than 150 species. For example, citrus, potatoes, celery, etc. have their own scab. The greatest damage to gardeners is caused by apple and pear scab, which we will talk about today.

Pear scab does not infect apples and vice versa, because they have different pathogens.

Pathogens of scab prefer dry and light soils with a pH of about 7, and usually overwinter in leaves that have fallen from the affected trees. Their active activity occurs in spring and summer, as soon as favorable weather sets in - the disease quickly spreads in wet weather (above 70%). Unfortunately, most often it is possible to detect infection already in the later stages - by the characteristic olive-brown spots covering the fruits and leaves. In addition to its own symptoms (and if the infection is massive, the tree can completely discard the leaves and fruits), the scab contributes to the spread and penetration through cracks and sores of other, more dangerous plant infections, which can even lead to their death.

Therefore, the focus should be on preventive measures, different for each particular culture.

Apple Scab - photos, description, treatment

The causative agent of apple scab is the marsupial fungus Venturia inaequalis. It hibernates on fallen leaves and fruits, and begins to dissipate the spores with the beginning of the growth of apple shoots. Young leaves that are at the top of a growing shoot are most susceptible to scab infection - a velvety olive bloom appears on their underside, darkening and transforming into spots of the same color over time.

As the middle of the spot grows, it grows brown and cracks, which contributes to the infection of the apple tree, for example, with rot. Ovaries, pedicels, young shoots and further fruit are also affected by scab. The affected parts of the plant dry out prematurely and fall off, the fruits lose their presentation - lose their taste, deform, become covered with spots that merge into a dense layer of "cork", and also fall.

Interestingly, although the disease has been known to gardeners for a long time, it has become a disaster only in the last couple of centuries. Before that, there were no large industrial landings, where a minimum distance was planted with many trees with the same genotype. Previously, apple trees were planted at a great distance among other fruit crops, which did not contribute to the strong development of scab.

If you do not take measures to save the garden, over time, the trees themselves show signs of infection with scab - over time, the bark will begin to crack, shallow shoots, fade flowers and not see fruit. Growth is also delayed and the winter hardiness of apple trees decreases.

What and when to treat apple scab? The scab control will be effective if at least three treatments of the garden with fungicides:

  • The 1st treatment is carried out in early spring at the very beginning of bud break (during this period 3% borde fluid is used);
  • The 2nd treatment is needed immediately after flowering (this time using 1% bordeaux liquid, Kuprozan or copper chlorine;
  • The third treatment is needed in 2-3 weeks after the second one (fit Skor, Ditan, Horus).

From folk remedies you can advise the treatment of apple crown tincture of garlic - chop 200-300 g of garlic, pour 2 liters of hot water, let it brew for 24 hours, then strain, dilute 8 liters of cold water and add 30 g of household soap.

  • 7 ways to use garlic in the country
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As we have already mentioned, the most important role in preventing the spread of the disease is its prevention:

  • Choose more or less scab-resistant apple varieties (disease resistance is controlled by 15 different genes, which are selectively introduced into new varieties): Suislepsky sustainable, Celandine, Abundant, Imrus, Aport, Antonovka, Prima, Red Fries, Priscilla, Topaz, Gypsy, Shtreyfly lezhky, China arcade.
  • Do not plant trees in solid rows, next to each other - thickened plantings have a positive effect on the development of the fungus and its activity.
  • Regularly pruning so that the tree has enough light and air.
  • Destroy sources of possible infection (fallen leaves, buds, branches and fruits).
  • Use new generation fertilizer with silicon for foliar fertilizing, which will help to heal trees and strengthen their immunity (Solfan PK, OptySil).

Pear Scab - photos, description, treatment

The culprit for scab pear is another fungus - Venturia pirina. It hibernates, unlike the previous one, on young twigs, and destructive activity, like the last one, begins in early spring with bud break. At the initial stage of the disease, spots of a greenish-brown color with a velvety patina (accumulation of fungal spores) appear on the lower side of the leaf plate. After that, the disease moves to the flowers and fruits. The foliage dries and falls off, the flowers fall off prematurely, the fruits become smaller, deformed, covered with dark putrefactive spots, the peel cracks. Pears become unsuitable for eating fresh or for processing.

Later, as the disease progresses, the bark begins to swell on the affected tree, becoming covered with ulcers and a spore bloom. Just as in the case of an apple tree, scab disputes are carried by rain, wind, insects and birds to neighboring trees, where they are hibernating, and in the spring they resume the breeding cycle.

How to treat pear scab? As in the above situation with apple trees, first of all, engage in the prevention of disease:

  • Grow scab-resistant pear varieties: Muratovskaya, Avgustovskaya dew, Nika, Rusanovskaya, Muscovite, January, Chizhovskaya, Krasnobkaya, In memory of Yakovlev, Cosmic.
  • Timely thin out the crowns of the trees so that the plants are well ventilated.
  • Remove the droppings regularly, and burn the fallen leaves, because they persist spores of the pathogen.
  • Periodically dig up tree trunks, especially in late autumn.
  • Use new generation fertilizer with silicon for foliar fertilizing, which will help to heal trees and strengthen their immunity (Solfan PK, OptySil).

If the plants are already infected, apply medicinal sprays of scab using the above scheme (as for apple trees) using Bordeaux mixture and, in advanced cases, with more effective fungicides according to the instructions.

Scab - a disease unpleasant, but it is quite possible to prevent and reduce the likelihood of infection of fruit trees at least twice. Of course - subject to the observance of these preventive measures and proper care of plants. Remember also that weakened trees are primarily affected, so do not forget about timely full-fledged feedings and treatments from pests.

Watch the video: Apple scab- a common disease of apples and pears (September 2019).