Pear and apple tree diseases

Apple and pear trees belong to the Rosaceae family like other fruit trees and are part of the pome fruit subgroup. Both species can be grown according to the principles and techniques of organic farming in all areas: soil management, pruning, fertilization and also protection against diseases and pests.

For the latter, it is important to act quickly and apply all preventive measures against orchard diseases. To do this, we need to be able to recognize any problems with the tree. So let’s take a look at the diseases that can affect apple and pear trees.


Main diseases affecting apple and pear trees

Punctuation. Scab is a cryptogamic (or fungal) disease that affects both apple and pear trees and manifests itself during the season by round brown spots with well-defined contours. These spots can be seen both on the leaves and on the fruits. Severe attacks, not taken in time, can lead to early defoliation of plants.

Powdery mildew or bad powdery mildew . Very common disease in many fruit, horticultural and ornamental trees (see for example zucchini powdery mildew), it is caused by several species of fungi which form in spring-summer white powdery spots on the affected organs – grayish . In the fruit, they cause surface deformations and oxidations.

fire bacteria . It is a disease that has spread since the end of the 1990s and is caused by the bacterium Erwinia amilovora, which attacks apple and pear trees, but also ornamental species such as hawthorn. Symptoms include wilting and desiccation of shoots, flowers, fruits and leaves, as well as a typical bacterial exudate. The name of the disease is connected with the appearance of the plant, which seems to have been burned by a fire that broke out next to it. The bacterium is favored by the presence of cancers on the trunk or branches, where it can overwinter. Flowers and hail wounds are the preferred entry points from which it spreads and multiplies, then colonizes flower pots.

Brown spots or alternating spots. The fungus responsible for this disease causes circular necrotic spots, often surrounded by a reddish halo. It affects pear trees, particularly Conference and Abate Fetel varieties, and is favored by warm and humid environmental conditions, the optimum being between 21 and 23°C.

disease prevention

In organic farming, the fundamental starting point for limiting epidemics as much as possible is the choice of resistant or at least tolerant varieties. It is often a feature of old traditional varieties, some of which were abandoned decades ago for commercial and production reasons. Fortunately, there are nurseries specializing in old fruits that reproduce them and make them available for organic cultivation.

Other preventive factors that should not be overlooked are:

  • Good ventilation of the foliage thanks to an adapted pruning.

  • Adequate plant nutrition, without excess nitrogen. You also have to pay attention to the doses of organic fertilizers such as pelleted manure and pollen.

  • Prompt removal of all plant parts affected by adversity to prevent fungal or bacterial spores from spreading to healthy plants. After leaf fall in autumn, dead leaves should be removed from diseased plants to prevent fungal spores from overwintering in the soil and spreading again in spring. In the event of a serious fire, it is advisable to eradicate the entire plant and burn it.

  • Preparation of certain macerates that stimulate the natural defense capacity of plants. Among them, macerated equisetum and garlic and onion decoction are recommended for spraying foliage.

Contains diseases with biological remedies

For organic farming professionals, but also for individuals who grow apple and pear trees, there are products on the market authorized by organic regulations. However, the ideal would be to limit its use after having previously worked on prevention. , which also has an effect on powdery mildew and scale insects, is mainly used against scab. It is also good for winter use, on overwintering forms of the pathogenic fungus.

For the rest, for the formation of crusts and brown spots, there are copper-based products, such as the classic Poltiglia Bordeaux , which blocks the development of the disease and should be used preventively, that is, after each persistent rain. However, this should not be overcome with copper-based treatments, as this metal accumulates in the soil and can eventually depress earthworm activity.

Powdery mildew has long been opposed to sulfur products , of which there are many commercial formulations (liquid, powder, etc.). Sulphur, however, cannot be used at low temperatures (usually below 10°C), and above 30-32°C it is phytotoxic, i.e. it burns plants.

You can then use potassium bicarbonate which, unlike sulphur, can also be used close to harvest. Also baking soda the one used in cooking, has a certain efficiency.

Defending apple and pear trees with organic farming methods and products is possible because, fortunately, there is a wide range of both preventive and curative solutions. The important thing is regular monitoring of the orchard, essential to detect the first symptoms in time and find the right remedy. Another good habit to adopt is to consult the phytopathological bulletins of the area where you are, where probable problems are reported.

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