Apple Scab Fight
Appeared scab on the apple tree is the reason for the shrinking of fruits and a reduction in apple harvest. Under the influence of the disease, apples lose their taste, are deformed and lose their keeping quality during storage after harvest.
Apple Scab Fight
Etiology of the disease
The causative agent of apple scab and the source of damage to leaves and fruits associated with it is a marsupial fungus.
It retains its vitality during the winter period, remaining inside the unripe fruiting bodies - pseudothecia, which formed in autumn on dead leaves and apples, in cracks in the tree bark and on dry dead branches.
With the active growth of apple shoots, the fungus begins to disperse spores, which are attached to the leaves through the mucous membrane.
At risk are young seedlings in which the upper tier of young leaves is affected.
At the initial stage, the scab fungal spores settle in the space between the leaf skin and the cuticle, without penetrating into the deep cells of the tissues. After 2-3 weeks, the conidial stage of development begins, in which, through the spread of conidia, the previously affected apple crown foliage becomes infected again.
Inflorescences, shoots and ovaries also fall under the destructive effect.
When the leaves fall, the scab continues its development in the form of a saprotroph, destroying the dead remains. At this stage, the fungus lays pseudothecia, which are activated upon the onset of heat, starting a new development cycle.
Harm from scab
Infection does not carry the harmful effects of horticultural culture, does not stop the processes of photosynthesis, while retaining the ability of trees to develop and bear fruit.
However, it is harmful to the crop, as significantly reduces its quantity and worsens the quality characteristics of the fruit, so the tree must be treated.
If the fruits are affected, then:
- they become smaller in size, deformed, become ugly in shape, acquiring an unattractive presentation;
- the amount of vitamins contained is reduced;
- gastronomic characteristics worsen - they get an unpleasant aftertaste;
- early fall of foliage;
- most of the fruits fall off in time.
Causes and symptoms
High humidity contributes to the spread of the disease
Moisture and heat are required for the active spread of scab, because the disease is widespread in climatic zones with warm weather conditions - especially in regions where cold and wet springs are observed.
A favorable factor for the emergence and active development of the fungus is an increase in ambient temperature to 20 ° C and above, as well as prolonged rains.
Among other reasons - violation of the basic rules of agricultural technology during cultivation:
- planting at a minimum distance from each other varieties with the same genotype;
- irregularity of pruning and the formation of the apple crown for the normal circulation of air flow;
In the process of apple infection, the scab foliage is covered with spots of light olive color.
Over time, the lesion foci grow in diameter, acquire a brownish tint and crack, opening the way for other viral, bacterial and fungal infections to enter.
Shoots, fruit cuttings and apples are covered with a rash that looks like a cluster of small dry spots and specks.
Chemical and folk remedies
The fight against scab on the apple tree is carried out by treatment with chemicals. When using them, the timing of the treatments is planned depending on the vegetation stage.
An alternative to pesticides is folk remedies. They do not have a toxic effect on and do not contain components harmful to humans.
With the mass appearance of the primary signs of the fungus, the garden culture is treated with pesticides:
- carbamide (urea) with a concentration of 10%: 100 g per 10 l of water;
- ammonium nitrate with a concentration of 10%: 100 g per 10 liters of water;
- potassium chloride with a concentration of 7%: 70 g per 10 liters of water.
Apple trees can be treated with any of the preparations no more than 2 times per season with an interval of 10 days.
Restrictions on treatment: do not use urea, nitrate and potassium at the stage of kidney opening, during budding, fruiting and harvesting.
Processing prohibited at the harvest stage
With the active spread of scab, to preserve the quantity and quality of the future crop, resort to the treatment of apple trees with fungicidal substances of 3-4 hazard classes:
- Chorus - recommended for the protection of young seedlings, it is used at an ambient temperature of 3 ° C, its effectiveness decreases when the temperature exceeds 25 ° C;
- Gamair - the drug can be used with an intermediate interval of 7-10 days;
- Phytolavin - a fast-acting composition that penetrates into the deeper layers of tissues, has resistance, therefore it is recommended for single use;
- Strobes - resistant to moisture, does not lose effectiveness when temperatures change, restrictions - up to 3 times per vegetative period;
- Speed - retains activity over a long period, it is recommended to re-process after 14 days to increase the effectiveness of treatment;
- Rayok - an analogue of the Skor complex, is able to quickly, in 2-2.5 hours, penetrate into the deeper layers of tissues, resistant to moisture.
You can fight with scab on apple trees with the help of folk remedies.
They are not dangerous for horticulture, therefore they are used regularly, incl. at the fruiting stage:
- fertilizer complex of the biological spectrum of action of Baikal-EM1, they should spray the soil on the near-stem circle, additionally mulching it with wood sawdust;
- concentrated solution of potassium permanganate, its use is acceptable for disinfection of tree bark and soil, in order to treat foliage, use a weak solution of potassium permanganate to avoid burns;
- saline - 0.5 kg per 10 l, the treatment is planned for a while after leaf fall.
Preventive measures against fungal infection help prevent its occurrence. To this end:
- they plan a sparse planting of apple trees, maintaining the recommended distance between them from 2-3 m or more, the average interval between planting dwarf and weak-growing varieties is from 2.5 m, for vigorous varieties - 5-6 m;
- destroy possible accumulation of fungal spores and other infections, carefully removing fallen leaves during autumn care;
- in the autumn, a deep digging of the soil is carried out, provided there are no signs of the disease in the current fruit and berry season, in cases of damage to apple trees, the soil is loosened to a shallow depth and treated with fungicides before wintering in the area of tree trunks;
- throughout the growing season, foliar dressing is carried out and apple trees are sprayed with mineral compounds;
- in the autumn, broken and diseased branches are cut, they clean the exfoliated tree bark and remove the lichens and moss that settled on it;
- in spring, whitewashed trunks at 2 m in height, skeletal branches and sections.
Resistant Varietal Varieties
Description of the prevention of fungal disease also includes the selection of scab-resistant varieties of apples.
Resistance is controlled by 15 different genetic units, which are taken as a basis by breeders and genetic engineering when breeding new species.
Processing can help prevent infection.
Among the immune varieties that show the least resistance to infection are Melba and the Golden Chinese. Relative Resistant:
- Orlinka, Apple saved and Medunitsa for Moscow region;
- Slav, Suvorovets and Friendship for the north-west of Russia;
- Spartan, Beforrest and Veteran for the Urals;
- Carmen, Lyubava and Argo for Siberia.
The degree of protection depends on the regional characteristics of the area of cultivation of garden crops.
To prevent the appearance of scab at the beginning (in spring) and at the end (in autumn) of the vegetation period, you can also process an apple tree.
- the use of chemical complexes containing fungicides and pesticides is planned for a time after leaf fall, but until the ambient temperature has dropped below 5 ° C, because low temperature reduces the effectiveness of the active substances;
- treatments are carried out in dry weather, in case of what happened after spraying rain, the prophylactic procedure is repeated;
- The whole garden is subject to spraying, on the trees they process the trunk, skeletal branches, shoots, paying special attention to cracks on the surface of the tree bark and places of growth of the kidneys;
- soil is additionally sprayed.
To prevent the appearance of fungus in spring, soil is watered with the Baikal-EM1 fertilizer complex. It helps to accelerate the decay of the leaves remaining from the fall and improves the composition of the soil.
Folk preventative tools that help create protection in the spring:
- Mustard. The best time to start the procedures with mustard-based solutions is the second half - the end of May. Cooking method - 4 tbsp. mustard powder per 10 l of water. To consolidate the effective result, spraying the apple trees with mustard is repeated after 2 weeks.
- Horsetail. Herbal infusion is prepared from fresh grass (a quarter of the bucket is filled with horsetail, poured 10 liters of hot water and held for 72 hours), filtered and the volume is increased with water to 10 liters. Frequency of use - regularly with an interval of 14-21 days.
Such preparations help protect apple trees from scab in the fall:
- Nitrafen - 100 g per 10 liters of water;
- Bordeaux liquid with a concentration of 3% - 300 grams of copper sulfate and 400 grams of limestone per 10 liters of water.
They are not sprayed with toxic chemicals at the stages of bud blooming, during flowering and fruiting, replacing these measures with folk remedies.
Scab significantly reduces the qualitative and quantitative characteristics of apple crops.
Appears mainly in regions with a warm and humid climate. It is often associated with violations of agricultural engineering rules (dense plantings, improper care, etc.). It is treated with chemical and folk remedies.
The best measure against fungus is the prevention and planting of infection-resistant varieties adapted to the cultivation region.