inconsistent fruit set vine to vine

[keverman]

Looking for a little direction.....this is a cluster from my 5 year old Marquette in Northern Ohio. About 60% of my vines have beautiful, full clusters and 40% look like this. Any thoughts on directions to head with this? Nutrients? Pruning? Other? I happened last year too and I blamed it on spring rain, but we had a pretty sunny period during bloom this year. I will admit the only learning I've done with pruning is reading and tutorials online, and I'm a hands on learner, so I feel like I'm guessing.

 

[salcoco]

I am guessing it is a nutrient deficiency. have you had soil test done? maybe just near where the vines are not setting? one trick I learned to add manganese to grapes was using Epsom salts in my spray tank . made the grapes look very healthy, other micro nutrients could be locked in the soil.

 

[Snafflebit]

I have shot berries on many of the vines I manage. Next year I intend to start a zinc daubing and zinc foliar spray. Are your vines grafted? That reportedly can cause zinc deficiency

 

[keverman]

I am guessing it is a nutrient deficiency. have you had soil test done? maybe just near where the vines are not setting? one trick I learned to add manganese to grapes was using Epsom salts in my spray tank . made the grapes look very healthy, other micro nutrients could be locked in the soil.

I have not soil tested yet. Sounds like I need to. Do you think a petiole test is warranted?

 

[keverman]

I have shot berries on many of the vines I manage. Next year I intend to start a zinc daubing and zinc foliar spray. Are your vines grafted? That reportedly can cause zinc deficiency

I think they are grafted.....

 

[salcoco]

any data you can obtain can be used to support any decision you make. soil test and petiole test are warranted.

 

[VinesnBines]

Salcoco, how much Epsom Salts per gallon? I love it for my garden plants but use about tablespoon per gallon of water.

 

[salcoco]

I don't recall but whatever seems good for the garden should not hurt the vines. might want to google magnesium deficiency in grapes and see if any thing pops. just did a quick google check and all kinds of documents out there on this topic and other micro nutrients. 5lb of Epsom salt for 75 gallons of water is a dose I found,is that a cup(8oz) per gallon?

 

[VinesnBines]

Re: Epsom Salts; I think it would be more like one dry ounce per gallon. 5 lbs x 16 oz = 80 oz.
Re: Poor fruit set, the VaTech research group says that rain during bloom may cause poor fruit set. The grape self pollinates and the rain can wash the pollen away from the bloom causing shot grape. At least I that was my understanding. Nutrient deficiency may be another culprit.

 

[Snafflebit]

in another source I link to:
Low Mg can corrected with foliar applications of Epson salt applied at a rate of 10 lb per 100 gallons of water in two postbloom applications.

 

[keverman]

I have a soil and petiole same pending, I'll posts the results in case it helps someone. I am also having some clusters dry up and die as if stem damaged or something....maybe mechanical damage? I had a few vines come off their wires and get man-handled, but I can't remember which ones. Also....YELLOW JACKETS HAVE INVADED! Help!!

 

[Snafflebit]

I had a petiole analysis performed. Symptoms pointed to zinc deficiency but it appears to be nitrogen deficiency.