Grape Anthracnose

2024 Author: Gavin MacAdam | [email protected]. Last modified: 2023-12-16 13:38

Anthracnose is an incredibly harmful fungal disease that affects grape shoots, leaves, berries and inflorescences. This ailment is especially widespread in Australia and America, as well as in a number of countries in Asia and Europe. The best conditions for its development are in the zone of humid subtropics and in regions with a humid and warm climate. And if spring is accompanied by precipitation, the disease will not spare, and young grape shoots and leaves that have just begun to develop. It will not be difficult to recognize this attack, so appropriate measures must be taken against it immediately - if you do not start timely treatment, vineyards can lose up to 70% of their foliage

Grape diseases: anthracnose

On grape leaves attacked by anthracnose, brownish specks often merge and are surrounded by dark white edges. The tissues in the places of their formation die off and crumble. And on grape shoots, first brownish-brownish, and subsequently pinkish-gray, depressed oval specks begin to appear. All of them are surrounded by dark edges, which often cover entire internodes. After some time, the affected tissues crack, and rather deep sores appear on the plants. Infected shoots break easily and dry out quickly. Most often, the manifestation of such symptoms is observed on leaf stalks and grape ridges.

Infected grape buds gradually turn brown and dry out too. And on the berries, the formation of grayish or brownish angular and rounded depressed specks, framed by dark edges, occurs. Each speck reaches a diameter of about 3 - 5 mm. A little later, the spots turn black and gradually cover the whole berries.

The causative agent of an unpleasant disease is a mushroom with the tricky name Gloeosporium ampelophagum. Overwintering of the pathogen is observed mainly on infected grape organs. And it persists for quite a long time (up to five years) in the form of sclerotia, pycnidia and mycelium, "waking up" in the spring along with the awakening of the kidneys. In just one season, this mushroom is capable of producing up to three dozen generations of harmful spores.

Outbreaks of anthracnose and its especially strong distribution are observed in most cases when rainy weather is established. The temperature of twenty-four to twenty-five degrees is especially favorable for the life of the fungus. The vine, struck by a dangerous disease, almost always freezes in winter.

Anthracnose grapes - treatment

When planting grapes, first of all, it is necessary to pay attention to varieties resistant to the ill-fated disease. Among these are Sauvignon, Rkatsiteli, Riesling and Traminer.

For prophylactic purposes, in early spring, vineyards (especially leaves and stems) are treated with copper oxychloride, "Polychom" or one percent Bordeaux liquid. And after a couple of weeks, this event is repeated.

To prevent fungal spores from freely multiplying on grape bushes, vineyards should be periodically ventilated. And the soil on which they grow must always be sufficiently moist. By the way, in order for plants to develop immunity to anthracnose, it is necessary to systematically fertilize it. Also, for preventive purposes, the leaves are sometimes wiped with a solution of potassium permanganate.

During the growing season, it is extremely important to carry out timely spraying with systemic and contact fungicides. You can treat vineyards with drugs such as Ridomil, Acrobat or Horus. Kuproksat, Poliram or Antracol will also cope with this task perfectly. It is perfectly acceptable to spray the vineyards with a product called "Thanos" or the famous Bordeaux mixture (one percent).

After each rain, it is recommended to spray the vineyards with high-quality copper-containing preparations. And when preparing them for wintering, it is necessary to remove all remnants of vegetation from the site and carefully process all the bushes again.