Hello, dear friends, today, by your numerous requests, we will answer questions about the grape diseases and how to cope with its pests and diseases.
The weather this year was very difficult: temperatures above 80°F (30°C) and heavy rains. All this affected the condition of the vineyards. Our expert Sergey Ksenofontov collects grape varieties, tests them on his site and makes marvelous natural wines from them. He knows how to grow this crop in these conditions and how to deal with its enemies.
How the disease progresses
I had no hope for any harvest until June, but then it got warmer, and hope appeared along with the warmth, especially since forecasters promise the same good weather in August and September.
While I was on vacation, spots appeared on the leaves of my grapes. These are signs of a common disease, powdery mildew, which on grapes is called just mildew. The disease can rob you of much, if not all, of your harvest.
Spots appear on the underside of the leaf plate, and they look like someone poured flour on the leaf. These are spores of the fungus. If you do not pay attention to them, in those places where the spores penetrate into the plant, yellow spots are formed, and eventually the entire leaf becomes infected. All its functions are disrupted, it stops nourishing the bunches and infects them with fungal spores.
Control of mildew
It is necessary to start fighting mildew in advance, i.e. from spring. Ridomil Gold is a good treatment for the pathogen, although it is not written on the package that it can be used on grapes. However, it is a fungicide of complex action, and it is effective against powdery mildew.
It is necessary to carry out 3-4 treatments before harvesting, and the last one should be done no later than three weeks before the harvest: the waiting period for this fungicide is 20 days, and if you have children running around your yard, they can try ripe berries and get poisoned.
Chorus has a waiting period of only seven days, and it also copes well with mildew. Spraying should be done in the evening, when the sun is hidden, otherwise Chorus can burn grape leaves.
Revus fungicide has an even shorter waiting period of 5 days and is also designed to control powdery mildew. Both of these fungicides can be applied just before harvest.
Copper-containing fungicides, such as Oxychome, also destroy the pathogen. As for biological preparations, their use on grapes, even as a preventive measure, had no effect. I experimented with different biopreparations for a long time, but there was no any effect.
Wasps on grapes
As soon as grapes start to ripen, the berries are attacked by wasps. Attracted to the garden by the fragrance of grapes, they also attack other fruits. I have found many ways of setting traps on the Internet, but they will not help to get rid of these pests completely.
I am a beekeeper and wasps destroy entire bee families in the fall, so I need to get rid of them. I have bought a bag of Actara and I am going to prepare baits for wasps in the form of minced meat or fermented juice to which I will add the insecticide.
The wasps take the bait and bring it back to their nest. In this way the entire pest population can be eliminated and the garden freed from pests.
However, many people complained that Actara does not work. The fact is that good preparations are expensive, so they are often counterfeited. You need to look for a bag with a holographic sticker. This is definitely not a fake.
If you cannot find Actara, you can kill wasps with boric acid. Dissolve it in syrup or simply mix the powder with minced meat.
The weather has surprises that we can't do anything about, but if you take care of your grapes properly and respond promptly to signs of disease, even weather disasters will not be able to deprive us of the harvest.
Next time Sergey Ksenofontov will tell you how to prune grapes in summer, but for now we say goodbye and wish you all the best.
References and links
- Vitis vinifera