Long vintage is coming to an end and weather conditions were kind to diligent vine growers, who fought successfully against the most important grapevine diseases – downey mildew, powdery mildew and phomopsis.
Until the beginning of the harvest, attention has to be focused on one more disease that, if not treated in time, can destroy the yearlong effort and harvest in a just few days. Grape rot or botrytis causes rot of berries and whole clusters. Brown spots appear on the affected berries that can spread and affect the entire surface of the berry. If at the time of ripening the weather is dry, the berries shrivel and dry too. However, if the weather is humid with plenty of rainfall, the berries appear ash-gray. This condition spreads from berry to berry. Dense clusters decay rapidly because crossing of infection on them is facilitated.
Infection occurs when, after a prolonged dry period, heavy rains cause a vine to abruptly pull water. Inside the berry a strong pressure occurs, causing a cracking of epidermis. Bursting places, cracked epidermis and damage (moths, wasps or hail) on berries are the front door for parasite attack. If the infection has occurred in dry weather, a part of the cluster under infection shrivels and dries. If the infection has occurred during rain, a whole cluster affects mycelium of fungus Botrytis cinerea.
In some climatic regions (western Europe), Botrytis cinerea is considered as the “noble rot” as its attack improves the quality of the harvest, causing the so-called “noble rot” of grapes. However, in other climate conditions, it is a major problem in wine growing, i.e. the primary factor that reduces the quality and quantity of the harvest.
The intensity of botrytis attack in nature is different in different varieties, which mainly depends on external climatic factors, as well as variety resistance. One of those factors, on which we can not influence, is moisture or rainfall before and during ripening. Infection severity, however, can be influenced by balanced fertilization and proper pruning. Vineyards fertilized with larger amounts of nitrogen become overactive, they have extended vegetation and are subjected to stronger botrytis attack. Also, more laden vines that are pruning-formed to have better radiation are less prone to be affected. Pesticides can also be used for botrytis control – botrycides based on vinclozolin, iprodione, procymidone and others. At the same time we must pay attention to the waiting period, because these products may adversely affect the fermentation of the grape must and the entire course of vinification.
It is very important to ensure good vineyard protection from powdery mildew, downy mildew and grape moths, because if damage occurs on the berries, the effect of botrytis is that much stronger.
When protecting the vineyard, the most important factor is to monitor weather conditions and protect your vineyard on time. Agrivi farm management system provides detailed weather forecasts 7 days in advance for each field, and alerts you if there is a possibility of disease and pest attack on particular fields, if the conditions for infection are favorable. With the disease or pest alarm, the system offers a list of active substances with which they can be treated and the commercial name of the product containing that substance.
Reduce the number of vineyard visits and stop guessing what the weather will be like. Use Agrivi farm management system and ensure you are ready for a healthy harvest!