Mark Kissinger wrote:Have you checked for root damage from burrowing animals, such as voles?
It would be a longshot since I would think if there was something eating the roots, or something in the soil, it would be affecting the entire plant.
F Agricola wrote:It's counterproductive to irrigate grapes in MOST circumstances - there will be a higher yield but a loss of flavour and watery fruit. Dry season grapes always produce better tasting, smaller fruit, also true for winemaking.
This year I tried a "dry" garden for the first time. Some of my grapes are along the edge of this area, so they of necessity weren't watered either.
Judith Browning wrote:
I don't know anything about the damage but I have always heard that grapes/muscadines need good winter moisture to bear well the next summer. Dry summers were good as they produced less fungus and mildew. This was our experience with muscadines that we cultivated in the wild. We never watered at all and could tell in the years when we had good winter rains that they produced better.
Mark Kissinger wrote:If you make wine, let us all know how your experiment worked!
Lauren Ritz wrote:Mark, the grape vines are between two houses, each about fifteen feet away, and primarily blocked from the prevailing winds. The piece affected is in the middle, about halfway down the row. It may easily be physical damage, but it's only affecting one area of the plant and the vines that go beyond that area are fine. It may be herbicide drift, but the area is suburban so I'm not sure where it would come from. The neighbors used to spray in that yard, but they moved out a year ago. It's entirely restricted to one area of one grapevine, the rest seems fine.
F Agricola wrote:If it is black rot, the normal fungicide used is called Bordeaux Mix, which is just a mixture of copper sulphate and lime.
But it needs to be used in conjunction with good vine and surrounding area hygiene, and used infrequently and strategically.
Joylynn Hardesty wrote:That was a beautiful harvest. Wow.
About the troublesome grapes, I think F Agricola was on the right track with the fungal suggestion. I suggest investigating black rot.
Mark Kissinger wrote:You might consider how much pruning is done to the lower parts of the vines. What sort of fall pruning do you do?
Just throwing out possibilities here.
Mark Kissinger wrote:Thanks for the reply.
Have you come up with a hypothesis about what to do next?
Jan Hrbek wrote:It is really hard to say what was the real problem with your grapes, but sunburn or water deficiency (or both) seems the most probable to me according to your pictures. If they were watered heavily in last years (as you write) and this year suddenly you stopped, drought might be the reason. Your vines have shallow root system, dependent on watering.