What causes rotten grape clusters after the bags are removed
Bagging grapes is a technique that prevents and reduces fruit diseases, and it also improves grape quality and increases market value. Many fruit growers regard it as an effective means of ensuring quality and increasing yield at low cost. But quite a few growers have also reported that rotten clusters appear after the bags are removed, which puzzles many growers. So what causes rotten clusters after the bags are removed from grapes? Let's take a look.
1. Improper bagging time
Grapes are quite particular about bagging time. Generally speaking, it is better to bag early than late. The bagging time is usually chosen during the enlargement stage. If bagging is done late, some fruits have already been infected by pathogens, and spraying medicine can hardly eliminate them. After bagging, they will still multiply inside the bag and harm the fruit. And according to experimental evidence, when bagging is done during the enlargement stage, the rotten fruit rate of grapes is only 2.5%, while bagging 20 days later gives a rotten fruit rate of 17.8%. So the bagging time for grapes must be well controlled.
2. Incorrect bagging method
Incorrect bagging time can also cause rotten clusters to appear after the bags are removed from grapes. Some people generally finish bagging grapes within 6 days after spraying medicine, but this is a wrong practice. Practice has shown that after spraying grapes, you should wait for the liquid medicine to dry and then bag promptly, preferably finishing the same day. If there is no rain that day and no dew at night, finishing within two days is also acceptable. If the planting area is large, you can bag block by block. According to your own actual situation, estimate how much you can bag in one day and spray that much medicine.
3. Problems with spraying medicine
The timing of spraying medicine before bagging is wrong. Do not spray when there is dew, and do not spray under strong midday sunlight or in strong wind, as all of these will make the spraying effect worse and may even backfire. The best time to spray is from 7-10 am, avoiding periods with dew and strong light. Spraying should be even, and it is not advisable to spray too much or miss spots. For trellis grapes, both sides should be sprayed, and for pergola trellises, both sides of the clusters should also be sprayed. The pesticide should be chosen well, such as azoxystrobin, benzyl azoxystrobin, etc. Never use counterfeit pesticides. The sprayer nozzle should use a fine swirl plate, which helps spray the medicine finely and evenly.
4. Paper bag problems
The benefits of bagging grapes include preventing diseases, preventing pollution, preventing bird damage, and preventing insect damage. It can also help grapes maintain yield, improve quality, and fetch a good price. But the paper bags used for bagging are also quite important. Paper bags produced from inferior paper by some non-standard manufacturers, paper bags made at home from newspaper, and paper bags that have already been used once will all cause rotten fruit inside the bag. Remember this point: be sure to buy standard, qualified wood pulp paper bags. Although the price is higher, they are safe and reliable.
The above is an introduction to what causes rotten clusters after the bags are removed from grapes. We hope it helps you. To learn more related knowledge, please stay tuned to us.