Knowledgebase
Orange spots on Itasca Grape Vine Leaf #878029
Asked July 20, 2024, 1:45 PM EDT
Cass County Minnesota
Expert Response
Thank you for reaching out to ask2.extension.
It looks like you have the start of grape black rot. The disease is caused by the fungus Guignardia bidwellii. The fungus can infect the leaves, shoots, berries, tendrils, rachises and cluster stems (peduncles) of grapes. If the disease is not managed early in the season, the impact on grape clusters can be devastating, resulting in complete crop losses.
If you go to extension.psu.edu and search for black rot on grapes in home gardens, the article will tell you half to deal with the disease and what to do to prevent it. It will also give you pesticides that you can use.
I hope this helps.
| Fungicides | P | BR | DM | PM | BO |
|---|---|---|---|---|---|
| Captan | 1 | 1 | 3 | 4 | 1 |
| Copper | 2 | 2 | 2 | 1 | 3 |
| Maneb | 1 | 1 | 1 | 4 | 4 |
| Mancozeb | 1 | 1 | 1 | 4 | 4 |
| Mycobutanil | 4 | 1 | 4 | 1 | 4 |
| Neem Oil | 4 | 4 | 4 | 4 | 4 |
| Sulfur | 3 | 3 | 3 | 1 | 3 |
On Jul 21, 2024, at 7:22 PM, Ask Extension <<personal data hidden>> wrote:
I would say the 1 is a better treatment than the 4 product. I think both would work but you shapely have better results with the 1 product.
