Apple trees in bloom – what a miracle. There really is no better color when apple trees are in bloom, and it’s heartbreaking when the orchard is literally abandoned in the summer. Disease-affected fruit rots under the trees. In years with epiphytic tree infestations, up to 90% of the crop dies.
Apple trees, like other orchard crops, are affected by 3 types of diseases: fungal, bacterial, and viral. In addition, each year, more and more orchard trees are affected by agricultural practices such as the use of fertilizers, water and temperature control, and the use of protection against pests and diseases. The enemy must be recognized by sight – only then can the battle for the harvest be won without harming the health of families and animals. A common enemy of gardening is the failure to maintain crops in an appropriate manner. This article allows you to learn what fungal and viral diseases of apple trees are and how to prevent and control them.
GENERAL AGRONOMIC MEASURES TO CARE FOR GARDEN CROPS
Placing the garden in fallow or fallow ground. Systematically eliminate weeds where pests and diseases gather.
Remove fallen leaves, fruits, and other debris from the vicinity of the garden every year during the growing season and in autumn. Diseased fruit is destroyed. Leaves from healthy trees are often placed in compost pits or used for mulching.
Apple trees are infected with the rust disease of common prickly cypress. Therefore, juniper trees should not be planted near orchards.
In the fall, after leaf drop, systematically inspect the trunk and trellis branches. Prune the canopy and remove diseased, dry, inward-growing branches. Clean off old bark shed from trunks and scaffold branches.
Ensure that holes, cracks, and crevices are sealed with special preparation. Thick cuts should be repainted or other protective substances.
Prune from February to March, when the plant is at rest (no sap flow).
Several times a year (not only in spring and autumn), but the trunk and scaffold branches are also painted white with a freshly prepared lime solution mixed with clay, copper sulfate, glue, fungicides, and fungicides.
In the fall, a phosphorus and potassium fertilizer is applied, and the soil is disinfected with copper sulfate, ammonium nitrate, and biological preparations before digging. If the garden is already sodded (no re-tillage required), drill 5-10 holes along the edge of the canopy, fill with the fertilizer mixture, cover with sod and water.
During the growing season, feed apple trees in the spring with ammonium nitrophosphate at 50-100 g per crown. Fertilize annually with micronutrients.
Irrigate at least twice in the summer (especially in dry times). After watering, cover the soil with mulch for shallow cultivation.
CONTROL OF FUNGAL DISEASES
Apple trees are infested with a disease-causing fungus. The fungus and its spores overwinter in fallen leaves, diseased fruits, cracks, and depressions. The overwintered spores, part of the fungus, begin to actively proliferate in warm spring weather, taking over healthy parts of the asexual and generative organs of the plant. The most common and harmful fungal diseases are fruit rot, powdery mildew, black rot, and other rot diseases, scab, rust, brown spot Cytospora.
Each type of fungus has its own unique signs and characteristics that can be unified by the manifestation of external symptoms. Fungal infections manifest themselves as individual oil-like translucent or rounded red and yellowish dry spots, grayish-white patches, various velvety touches, and circles formed on the leaves. They turn yellow, curl, and stop growing. Individual round spots appear on the fruit and proliferate. Fruit tissues begin to rot or become lignified and dehiscent. Fruits are mummified on the branches and then fall off. The most favorable conditions for the spread of fungal diseases are warm, humid weather.
You always want to grow healthy organic crops at home, so some gardeners think it’s best not to use any preparations at all. But this is fundamentally wrong because, after a few years, there will be nothing left in the garden except wilted or completely diseased plants. Protective measures in the garden are a must. Biological preparations made on a natural basis – beneficial microflora destroying disease-causing fungi – are now used in garden treatments. These preparations are completely harmless and can be used the day before harvest.
Protection techniques using biological agents
In autumn, on the bare canopy of apple trees, and in spring, before waking up from winter rest, blue spray with a 2-3% solution of copper sulfate.
In spring, before germination, disinfect the soil with a 7% solution of urea or a 10% solution of ammonium nitrate. Thoroughly spray the soil in the root zone and dig at 4-6 inches (10-15 cm) after 2-3 days.
At the pink bud stage and every 7-10 days thereafter, treat apple trees with a biological preparation “Xylophilus spp.”, “Phytosporin,” as recommended. They can be used to treat the garden until harvest, and the use of biological agents containing fluorescent pseudomonas “Pseudomonas fluorescens” helps to prolong the shelf life of the product. In order not to cause dependence of negative microflora on the preparation, it is necessary to constantly change biological preparations when treating plants.
Remember! Biological agents do not alleviate the disease with a single treatment. Systematic treatment of trees is necessary. Maximum effect can be achieved in the second or third year.
Chemical measures to protect apple trees from fungal diseases
Insect infestations in orchards are sometimes so severe that biological agents do not have any effective effect on infected trees. In such cases, chemical protection measures can be applied.
When using chemical agents, it is important to observe health precautions (protective clothing, gloves, goggles, helmet). After work, wash your face and hands with soap and water or take a shower.
Protective measures start in autumn. After removing weeds, leaves, and fruits, spray apple trees blue with a 3% solution of copper sulfate.
In spring, before the buds open, the blue spraying can be repeated, treating the crown, or using a 1% DNOC solution.
As a preventive measure, instead of copper sulfate and DNOC, the soil in the crown, stem, and root zone can be sprayed with a mineral fertilizer solution. Carefully treat the crown with a 5% solution of urea and the soil with a 7% solution. A 10% solution of ammonium nitrate or a 15% solution of ammonium sulfate can be used to treat the trunk and branches. After a few days, the treated soil should be turned over to a depth of 4-6 inches (10-15 cm).
During the green cone stage of leaf buds, before and after flowering, treat the canopy with Bordeaux mixture at 1%. Bordeaux mixture is effective in protecting trees from scab, moniliasis, powdery mildew, and other fungal diseases. It is not toxic, so it is allowed to treat trees with its solution after flowering.
Starting from the rosebud stage, apple trees are treated with a plant growth regulator every 2-3 weeks according to the instructions. Spraying was stopped during flowering. The last treatment is applied one month before harvest or at the fruit setting stage.
To reduce the burden of the number of treatments, you can instead treat the trees with a mixed tank in the protection system, checking the compatibility of the preparations beforehand.
VIRAL DISEASES AND BEST PROTECTION TECHNIQUES
Viruses are tiny protein particles that are invisible with an ordinary microscope, but harmful enough for living plants. They are spread by pests through open plant tissue (grafting), water, and wind.
External symptoms of the disease
At the beginning of the introduction of the virus, its destructive work is not obvious, and the plant continues to function as a healthy plant. The appearance of the disease resembles a fungal infestation. Spots appear on the leaves, and the fruits are deformed. As time passes, these differences become more pronounced. Individual spots on the leaves merge into a mosaic pattern of greenish-yellow colors and tones. The leaf layer becomes necrotic, and the affected leaves fall off. Flattening and flattening of the shoots and softening of the wood can be observed. Branches become unusually soft and rough and break easily under the heavy pressure of the crop. Individual flowers and inflorescences become severely deformed and take on an ugly shape. During spring development, a bunch of dwarf shoots with leaves or only leaves of unusual shape and color is formed at the end of young shoots. A bunch of greasy shoots (witch’s ring) is formed on the older branches. Fruits crack, form crusty spots and excrescences, lose their flavor, and also fall off.
The external manifestations of viral diseases determine their names. The most common viral diseases of apple trees are mosaic, starry split fruit, panicle (witch’s broom), rosette, hyperplasia, or epiphytotic of asexual and reproductive organs (ugly), green ring spot, and wood pockmark.
There are no preparations to eliminate the source of infection of this virus. Therefore, the main control measures are agricultural farming techniques.
Agronomic measures are the same as those used to control fungal diseases. Special attention should be paid to the following measures.
Pruning is carried out only when the plants are in deep dormancy (February).
When pruning, all diseased parts of the plant and the whole tree should be removed. Do not use the waste material for composting.
If rosette and panicle disease, the most common diseases on apple trees, are evident, use reduced doses of simple forms of phosphorus and nitrogen fertilizers. Switch to complex forms of fertilizers in which the elements are in optimal proportions for the cultivated crop.
Introduce micronutrients, including zinc sulfate, in dressings, especially if there is evidence of rosette formation.
Spraying with phytohormones to improve the immunity of plants to viruses. These agents are effective as a preventive measure. However, they do not stop the development of the disease.
Note! The main defense against viral diseases is the suppression of sucking pests that are the main carriers of viruses.
SYMPTOMS OF BACTERIAL INFECTIONS
The most common bacterial infections are bacterial scald, bacterial root rot, bacterial necrosis, and bacterial spot disease.
Typical symptoms of a bacterial attack on the above-ground organs of apple trees are as follows.
In bacterial rot or bacterial necrosis, blisters appear on young shoots, which open up and expose the internal tissues of the plant. Leaves are covered with brown spots. Generally, the affected organs of the plant are indented and range in color from pinkish-brown with a purple border.
In bacterial scorch disease, affected branches look like they have been scorched by fire. The manifestations of the disease begin in early spring (bud bloom) when the generative and vegetative organs turn brown and black and stop growing and developing. Trees can die suddenly or become covered with blisters of varying sizes filled with bacterial slime. It oozes from wounds, ovaries, cracks in the bark, and ruptured blisters. It covers the affected organs with a gray film or solidifies into milky droplets. The multiplying bacteria migrate from seedlings to larger plant organs through blood vessels, causing the death of the entire plant.
In bacterial root rot, the disease appears first on the root neck and then on the trunk and branches, showing smooth growth that turns explosively brown or black over time. These bacteria penetrate the tissues and flourish through wounds, cracks, cuts, and insect damage to the integrity of the bark. They cause increased division of tissue cells, which leads to overgrowth and the formation of swellings. Inflorescences decay over time, and bacteria transfer to healthy tissues in above- and below-ground organs, including the roots. Growth occurs at the roots, and the swelling becomes hard. Above- and below-ground organs do not function properly, and the tree dies.
REMEDIES AGAINST BACTERIAL WILT
As with other diseases, the basic remedy is good orchard management. In order to keep it “healthy,” not only must all procedures be carried out in a timely manner, but measures must be taken to prevent pathogens from entering the garden. To do this, you must.
- plant with planting material of absolutely healthy zoned varieties, preferably from a specialized nursery.
- always disinfect working tools, especially during grafting, pruning, and other procedures that destroy the integrity of the plant’s outer skin.
- If treatment with preparations is ineffective, trees must be destroyed outside the garden and locations within the garden thoroughly disinfected with fungicides, mineral fertilizer solutions, copper or iron sulfate.