Dead spur

The first noticeable sign of the disease is the yellowing and premature falling of leaves directly on the fruiting spurs, which appeared healthy just recently. Subsequently, the fruit-bearing organs themselves dry out, becoming brittle, darkening, and turning brown or black.

Characteristic depressed spots often appear on the bark of infected spurs, which eventually enlarge and girdle the entire twig. As the process progresses, the bark tissue dies, and the wood beneath can become covered with micro-cracks or fungal spore deposits.

During the flowering period, affected spurs often fail to form ovaries, or the ovaries shed en masse because the organ's vascular system has been compromised. The tree begins to look thin, and total fruit yield drops significantly due to the loss of reproductive organs.

Gradually, necrotic processes can spread from small spurs to larger fruiting branches, leading to the exposure of skeletal branches and a significant decrease in the overall volume of fruit production in the orchard.

If action is not taken in time, necrotic ulcers form where the spurs died, serving as entry points for secondary infections that attack the main branches of the tree.

Dieback of fruiting spurs is a complex problem, most often caused not by a single specific parasite, but by a combination of pathogenic fungi from the genera Cytospora, Monilinia, and Phyllosticta. These pathogens often activate in weakened tree tissues.

The causative fungi overwinter primarily in infected bark, mummified fruits, or inside dead spur tissues, remaining viable for several seasons even under unfavorable environmental conditions.

In spring, pathogen spores spread by wind, raindrops, or insects, landing on young spur tissues through natural openings (lenticels) or micro-cracks formed by temperature fluctuations or pest damage.

A biological feature of this group of fungi is their latent development inside plant tissues, which is why external symptoms appear only when the spur's vascular pathways are blocked by necrosis.

The type of disease is classified as a necrosis-wither type, as the pathogen's main strategy is to destroy the cambium and bark, leading to organ death due to impaired nutrient supply.

The main factors contributing to the disease are sharp temperature fluctuations in late winter and early spring, which cause sunburn on the bark and subsequent tissue cracking, opening a path for infection.

High air humidity and frequent precipitation during the growing season create ideal conditions for fungal spore germination on the surface of fruiting twigs, especially in the absence of proper crown ventilation.

Weakening of trees due to unfavorable growing conditions, such as poor soil, lack of moisture during dry periods, or excessive nitrogen fertilization, makes spurs more vulnerable to pathogen attacks.

Insufficient maintenance of the crown, including lack of timely pruning and overcrowding, prevents moisture from drying quickly on the tree surface, which triggers the development of fungal infections.

The presence of other disease outbreaks in the orchard (black rot, fruit rot) significantly increases the risk of spur infection, as spores are constantly present in the immediate vicinity of the fruit-bearing organs.

The damage caused by spur dieback lies primarily in the direct loss of the current year's harvest, as the bulk of apples and many other pome fruits are concentrated on these organs.

Continuous infection of spurs leads to tree exhaustion, as the plant must expend additional resources on healing wounds and forming new fruiting twigs instead of normal fruit production.

Reduced attractiveness and vitality of the plant as a whole: trees with massive spur dieback become susceptible to winter freeze damage, which can ultimately lead to the death of an entire skeletal branch or the tree itself.

Economic damage consists of expenses for protective measures, the need to remove large amounts of infected wood, and the loss of fruit marketability due to the overall suppression of the plant.

A neglected disease creates a long-term source of infection in the orchard, requiring regular and expensive chemical treatments to contain the spread of spores to healthy parts of the orchard.

The basis of protection is timely sanitary pruning: all infected and dried spurs must be cut out with a margin of healthy tissue and must be removed from the orchard to prevent re-infection.

It is necessary to conduct regular preventive sprays with copper-based preparations at the "green tip" stage and after flowering, which creates a protective barrier against the penetration of pathogenic fungal spores.

Ensuring high agricultural standards: regular fertilization with phosphorus and potassium fertilizers increases the overall resistance of tree tissues to infection and promotes better wood maturation.

Protection against sunburn by whitewashing trunks and the bases of skeletal branches reduces the risk of cracks through which infection can easily penetrate deep into the spur.

Regulating crown density through pruning allows for improved air circulation, which prevents moisture stagnation and inhibits the development of fungal colonies on young fruit-bearing organs.