Black rot in grapes
Asked August 16, 2019, 8:47 AM EDT
Which is the best fungicide to use to prevent black rot?
Middlesex County Massachusetts
To prevent black rot on the berries you need to treat with a fungicide from bloom to veraison. Most grapes are susceptible for 3 to 5 weeks and then the berries become resistant. There are fruit spray mixes available that contain mixes of insecticide and fungicides to control both insects and diseases. Home owner fruit pesticides containing captan are effective. There are also mixes which contain pyraclostrobin, which is very effective. There is also a fungicide available which contains myclobutanil which is very effective. You can buy these materials at garden stores and you need to look at the ingredient list to find the active ingredient. You should read the label before purchasing and using these materials there are restriction on the number of times they can be used and recommendations to rotate the products to prevent fungicide resistance to the product. I would recommend starting with the Captan spray at bloom and then alternating the myclobutanil and pyraclostrobin sprays about every 10 day and shortening the interval if it is rainy.
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