Cytosporosis and rust of pear and apple

Cytosporosis and rust are fairly common problems for apple and pear trees. By correctly identifying the disease and applying the necessary measures, you can put these unpleasant problems behind you and enjoy a bountiful harvest. Of course, plant yield is influenced not only by diseases, but also by variety, weather conditions, fertilizers, and much more.

Cytosporosis - how to identify it

This fairly common disease affects the bark of fruit trees in the central and northern regions of European Russia. Symptoms are similar to those of black canker. A slightly depressed, rusty spot initially forms on the trunk and the bark of skeletal branches. Cracks appear at the junction between the affected and healthy tissue. The bark tissue frays when separated from the wood. Pycnidia, or spore-bearing cells of the fungus, appear as black nodules and are distributed randomly across the bark, unlike those of black canker, where they are smaller and usually clustered around the initial infection site. Cytospora initially attacks branches wounded or damaged by frost, then spreads to healthy tissue.

Methods of control

Remove and burn affected branches and whitewash the trunks with lime solution. Coating the wounds with garden pitch (petrolatum) in a layer up to 3 mm thick gives good results. Do not apply petrolatum during sap flow. SM is successfully used for wound dressing. This thick, gray paste is applied to the cut surface with a brush or stick. The paste does not spread and hardens within a few hours, resistant to precipitation. The product promotes callus formation on fresh cuts. Callus formed under the product film has a denser consistency, hardens well, and is highly winter-hardy.

Apple and pear rust

This disease appears as rounded orange spots on the upper surface of the leaf. In July, cone-shaped growths—clusters of rust spores—appear on the underside of the affected leaf. However, these spores cannot infect leaves. To develop further, they need to land on junipers: apple rust spores on common junipers, and pear rust spores on Cossack junipers. Here, they germinate, resulting in overwintering mycelium. In the spring, gelatinous growths—clusters of spores—appear on the infected juniper. These spores, carried by wind or rain to apple or pear trees, germinate and infect them.

Severe rust disease affects both leaves and shoots. Juniper is removed near gardens, and high protective belts are planted to prevent the introduction of fungal spores. Three sprayings of the garden are recommended: 1% Bordeaux mixture, polycarbacin (0.4%), zineb suspensions (0.4%), colloidal sulfur (1%), or other fungicides. The initial treatment is carried out during the green cone stage, with subsequent treatments occurring one to two weeks later (before and immediately after flowering). Polycarbacin penetrates the internal tissues of the plant and prevents infection by parasitic microorganisms. "Blue" spraying, i.e., spraying trees with a higher concentration of Bordeaux mixture (4%) at the very beginning of bud break, produces good results.