Bubble on stone fruits
The bubble on the stone fruits is a disease caused by a fungus called Taphrina deformans. This tiny mushroom winters on fruit trees, especially on peach trees, hidden near the buds, or in the fissures of the bark. The development takes place above all in cool and rainy periods, with temperatures below 18 ° C; in fact this pathology occurs above all in the central northern regions of Italy, in the spring period. When the first buds bloom, the fungus begins to develop and attacks the young leaves; the symptoms are clear and evident: the foliage appears red, or yellowish, with evident blisters similar to blisters, and thickened leaf lamina, with a rigid consistency. The leaves fall within a few days, and the spores of the fungus, which appear as a whitish patina, move on the fruits, on the wood or on other leaves. The poor photosynthetic capacity of the affected leaves and the defoliation cause a strong deterioration of the plant; the affected fruits block their development and fall to the ground.
How to get rid of it
The fungus that causes the bubble on the stone fruits can easily withstand the winter cold and mild spring temperatures; its development stops only when the climate becomes warm, with temperatures above 18-20 ° C, and a dry climate. Therefore, it survives on the plants throughout the year, waiting for the period most favorable to its development. Generally the treatments are preventive, in order to crush the fungus when it is still in its embryonic stage, or when it has not yet attacked the plants, but simply hides on the trunk or branches. The treatments typically are practiced in late autumn, and in late winter, before the buds become enlarged. Some fruit qualities tend to be attacked more easily by this problem, and the cool and humid climate favors the development of fungi: in these cases treatments are practiced even when the buds begin to swell, but always before flowering.
The products to use
The drupaceous bubble is fought with specific or generic fungicides. The most classic treatments are carried out with copper-based products. Copper is a broad-spectrum fungicide, which is used against the most common bacteria and also against diseases caused by fungus; copper-based treatments are performed when the plants have no leaves, especially on peach trees; this is because the product can be absorbed by the leaves and have a phytotoxic effect. Plants that tolerate copper well can also be treated in late spring, but with lower concentrations of the product. Specific fungicides, such as dodine, ziram or tiram, are also used against the problem; also these products are used as prevention, during autumn or winter, from November until February; in this way we try to defeat it before its development begins. The leaves and fruits of plants affected by the bubble must be collected and destroyed.
The bubble of the stone fruits develops in the first weeks of spring or towards the end of winter, in the period of the year when the climate becomes less rigid, and the plants begin their vegetative development. In this period the mushrooms find tender and thin leaves at their disposal, in which it is easier to penetrate. But there are predisposing factors that favor the development of the pathology, even in other periods of the year. These mushrooms love a cool and humid climate; in particular spring periods, when the climate is decidedly cold, with maximum temperatures below 18 ° C, the bubble may reappear, also attacking already well-developed leaves or fruits that are growing. Similarly, with the lowering of temperatures at the end of August, the fungus can resume its development, also attacking plants close to those that are sick. It is therefore important to import the work of prevention, together with the treatments with fungicides to be practiced on the plants affected by the disease, in order to avoid that the mushrooms, through the air or the rains, move to other plants of the orchard.