We are now up close and personal with our Chenin Blanc as we shoot tuck and move the netting into the proper trellis slot for deployment. Before the hurricane-AKA-tropical storm Ida came, our Chenin Blanc berries were green and hard indicating that they had not yet left the lag phase of development. After the storm, the berries were beginning to soften and are now in the ripening phase, véraison.
We have been noticing, even during the lag phase that our Chenin Blanc looked like this:
We thought that it might be sunburn and by searching the Internet, we came across an article written by
American Vineyard called
Preventing Sunburn on Grapes. What drew me to this article was this photo:
1
It certainly looked like what we were seeing in the Chenin Blanc so I read on.
Sunburn can happen during any stage of fruit development if the conditions are right which include too much sun, not enough shade and low humidity. The bunch may be soft at first, but after a period of time, the affected area dries up and creates a berry that is hard on one side and partially mummified.
Here is an example from our Chenin Blanc:
The advice on these sunburned grapes is to drop them.
More recommendations from the article include:
- Leaf pull between bloom and véraison
- Early leaf removal prevents the grapes from sudden exposure to strong sunlight late in the season
- Leaf removal should involve only 2-4 leaves on each shoot
- Skip leaf removal if vines lack strong vigor
- If possible, drape a shade cloth over the fruit to decrease the amount of direct sunlight
Their advice for long term strategy include:
- Orient the vineyard rows in a north-south direction
- Provide adequate nutrients (especially nitrogen, phosphorus, and potassium) to the plants, to support strong canopy growth
- Vines can be watered using overhead irrigation like a sprinkler or hose during periods of hot temperatures to create an “evaporative cooling” effect
References:
1.
American Vineyard,
Preventing Sunburn on Grapes, July 24, 2020.
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