Causes of the appearance and fight against rust on the leaves of an apple tree

Have you noticed orange-yellow spots on the leaves of the apple tree? In a healthy tree, the leaves do not change color and shape. Damage is a symptom of a disease or attack of a plant by pests. Rusty spots may indicate a fungal infection of a fruit tree, especially since apple and pear trees are the most vulnerable types of garden plants. How dangerous is the disease, what consequences can it lead to? Why does it affect apple trees and is there a risk of damage to other horticultural crops? Let's figure it out.

Rust on the leaves indicates the appearance of the disease

Rust on apple leaves

Apple rust is an infection caused by the fungus Gumnosporandium tremelloides. Usually, the first symptoms of the disease appear in mid-summer: small protrusions appear on the leaves and quickly grow over the entire surface. Soon stripes or round brown spots appear on the outer part of the leaves.

Black blotches are visible on the spots - they appear in places under which there is a cluster of spores.

Periodically, this hotbed opens and throws a new portion of pests onto the plant. Multiple yellow-brown spots occupy 2/3 of the leaf surface, the tree quickly sheds the affected leaves and already in August - September its branches become bare.

What is the danger of rust?

Rust often affects the leaves, but the fungus can spread to the branches, bark and fruits of the plant. Young shoots are at risk - some of them die off, and those that develop will not give healthy growth and fruits in the future. The development of shoots can last up to 3 years, but then the bark in the affected areas and on the trunk begins to crack. Apples do not ripen - at some stage (for each plant individually), they slow down growth and fall off.

Rust weakens the tree, resulting in a poor-quality crop.

A sick apple tree does not receive the nutrition necessary for normal growth, as a result of which photosynthesis and metabolic processes slow down, the plant lacks moisture. As a result, gardeners get a poor-quality crop - the fruits are small, they do not have the usual juiciness, the core is often rotten.

Causes of the disease

The most vulnerable is the apple tree, which grows in the same area as the juniper, because this plant is the causative agent of rust. In the cold season, fungal spores accumulate and hibernate in juniper needles - they can stay in a conserved state for several years. With the onset of heat in spores, the phase of active development begins - they settle on the leaves of apple trees and infect plants.

Rust is a common disease in the southern and coastal regions. In a humid climate, spores develop faster, and strong winds carry them 40-50 km away, affecting fruit trees in this perimeter.

How to deal with rust?

Yellow-brown spots should be treated so as not to harm the tree:

To remove rust, remove juniper from the garden

1. If the cause of the defeat is juniper, it is advisable to remove it from the garden and dig deep into the soil in the place where it grew.
2. Branches and leaves on which spots have appeared will have to be removed. They need to be cut 10 centimeters below the affected area.
3. After removing diseased areas, the plant is treated with Bordeaux liquid (1%) or other meldic solutions. The apple tree is sprayed three times, every two weeks.
4. A common mistake gardeners make is to start treating the tree at the end of summer, when the apple tree has already shed its leaves. Such measures will have no effect.

Rust treatment in early spring is most effective.

The best time for treatment is early spring, before the buds open. First you need to clean the wounds on the shoots (cut as described above) and disinfect the sections with a solution of copper sulfate. After that, you can spray the tree:

• spraying - in the "green cone" phase;
• spraying - in the "bud" phase;
• spraying - after the flowering of the tree.

How not to harm?

It is impossible to treat spots and other lesions on the leaves with Bordeaux liquid in the heat. At high air temperatures, the pesticide begins to actively evaporate, its concentration on the leaves of the fruit tree increases several times. An apple tree can get burned, and a gardener can get poisoned by toxic fumes. Breeders recommend spraying plants in the morning or evening when it's cool outside.

Treatment of plants in wet weather will not give a positive result, because the solution will drain from the foliage along with dew drops.

Spraying is carried out when the apple tree is dry. After rain, at least 6 hours must pass. There will be no positive effect from processing the fruit tree at temperatures below +5 degrees, and the apple tree may get burned.

The same thing will happen if you spray the plant in the heat or right after rain. In such climatic conditions, copper sulfate, which is part of the Bordeaux mixture and similar preparations, is released in excess. It causes burns of leaves, shoots, trunk.

Don't want extra problems? Then do not plant conifers in the same area with fruit trees. And if you take the risk, choose apple varieties with strong immunity to scab and fungal infections, surround plants with other fruit tree varieties, and properly care for the garden.