The ripening of Swenson Red grapes

Last year I had lovely red clusters/bunches of grapes, this year my Swenson Red are still green with a smattering of Red, and Dead grapes. My terrace smells like a vineyard! Why are they not ripening in clusters? Also, my white Hope grapes are ripening beautifully, are seedless and so sweet this year. I think they really take a while. This is their sixth year and I have only six clusters (bunches) they are very slow growers compared to Swenson’s Red. The latter grows like a weed. Given their pattern of ripening so little can be done with them. What is wrong? What am I doing wrong? thanks. Mrs.G

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I doubt if your doing anything wrong.

Heavy dew or fog may interfere with set. Also cool, moist air near the ground may interfere with set.

Swenson Red is susceptible to downy mildew.

Thanks, I can’t think of anything I’ve done wrong too. It is just so non-productive after you wait a year for all to be better.

If you have dead grapes you could have black rot, or you could have grape berry moth infecting the grapes. Look up those two and see if there is a match.

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Also, Swenson Red is notorious for flowers in the center section of clusters that fail to set, making the mature cluster dumbbell-shaped. Nothing can be done for that.

Will do! Have had moths this Summer!

Yes! Grape berry moth. Too late to Spray? Many clusters left! Thanks Scott!

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You probably know more now about GBM than I do now, its one pest I never got. Maybe someone else has had experience with it.

Is it usual for Swenson Red to bear two crops each year? Mine consistently does that. The second crop is just beginning to ripen. Sorry if this is off topic.

Scott went back out thid afternoon and I now think it is blqck rot, as I am finding mummies too.

Black rot is more likely based on what I know, pretty much any grape planting in the east will get black rot eventually … something like 5 years on average. I started a non-organic spray on my grapes when black rot hit, myclobutanil clears it out.


Thanks! Scott! I have that. Will spray after the rain stops.