Major Pruning & Red Spots on grape plants

[CaptainK]

Hi All,
Too make a long story short. We moved into this house 1 1/2yrs ago. There is a trellis in the backyard on which what we believe are 3 grape vines growing. Again this summers all 3 vines are about 8ft in length and are growing along the trellis. They did not produce fruit last year.
Like last year, they have developed these red spots on the leaves. They are small in size and feel slightly bumpy.
I have never had grape vines, which I am assuming these are. Could someone offer some advice on how to find out what these red spots are and also how to properly care for them so we can get them to produce fruit?

Thanks,
CaptK

[The Helpful Gardener]

Red spots are almost certainly fungal infections (albeit low-grade); we like neem oil for that sort of thing.

Sure these are grapes? Three years without fruit makes me suspicious...

HG

[opabinia51]

Had a similar fruiting problem with my mother's grapes. (At least, had to wait three years until a bumper crop came along).

The answer to the problem was simple: Pruning.

Prune the growth from this year to the third bud this winter and late fall.

Ideally, there shold be a lateral vine every 1 1/2 feet. You can build a trellise to espallier the growth of next year.

Incidentally, after doing this for my mother's grapes last year; this year... Grapes, grapes, grapes coming out of her ears.

By the way, the best thing you can do for a plant with a fungal infection is leave the plant alone and feed the soil with leaf mulch, manure, grass, kelp meal and manure. The plant will be that much more healthy next year and that much more able to deal with an opportunistic fungus.

[grandpasrose]

Right on Opa! We have grapes here, and the length of the vine does not tell how old it is but the size around the trunk. When you have a relatively new vine (up to 4-5 years) they may not bear fruit, or very little.
The secret to bumper crop grapes is pruning and limiting new growth so that the plant produces more fruit. They also need large quantities of water.
VAL (Grandpa's Rose)

[The Helpful Gardener]

True enough guys; I hard pruned the Ma in laws grapes this spring (last year was a fruitless first year) and they loaded up hard this year (we had a rainy spring; excellent for grapes). Look at vineyards where that vine has 4 or 5 inches of caliper and it's only 6 feet tall. There's a good clue in how to deal with them. I pruned just as leaf was getting ready to break; late by some folks standards, but I got almost no bleeding and the results have been spectacular. Also of note: th MIL was horrified by how much I was taking off when I did it, but she's thrilled with the results...keep that in mind next year.

Any thoughts as to a fall pruning after leaf drop? I did not this year and it worked well, but I notice the vineyards do a prune to knock back longer vines and then a hard prune in spring. What's the consensus?

HG

[grandpasrose]

I don't normally do a formal prune after leaf drop, though I must admit, that I like to snip at my grapes here and there during the summer if I think it is misbehaving!
I think it would be fine to do a mild prune in the fall. What do you think Opa?
VAL

[opabinia51]

Late fall, yes. Early fall, no. I just get a little queezy about the grapes bleeding.

By the way, since the topic of leaf drop came up. (And since that I am a huge composter) Grape leaves are great for the soil. They are very high in nutrients. I have the actual nutrient values in the organic forum.

[CaptainK]

Thanks for all of the info everyone.
Can someone please explain to me about pruning grape vines/leaves. I want to be sure I am doing he right thing and not just going in and chopping everything off. Things like when to do it, how to do it...ect ect.

Thanks!
CaptK

PS - I am really not sure how old these are. All I know is that we have been in this house for a 1 1/2yrs and that I want to see if I can get them to grow/produce fruit.

[grandpasrose]

I am no expert, but this is my interpretation of the way to prune and maintain grapes. The first thing to know is that grapes are vigorous and forgiving so any mistakes will be able to be corrected next year.

Grapes bear fruit on the green shoots that grow from one-year-old canes. The old canes that produced fruit this season will not produce again. In your case, yours have not produced fruit, but it is still an established vine.

There are a couple of ways to prune established grapevines. Cane pruning is the usual system. For this, you establish a permanent trunk, and every year new canes are selected from the head of the vine, where the trunk and wire or trellis intersect. Choose one or two canes on either side, each 8-10 buds long, and tie them to the wire, and cut all other canes out. Choose canes about the thickness of your little finger and come out as close to the head as possible, with buds fairly close together. Avoid large thick canes with buds spaced far apart. Also leave one or two spur canes, cut to two buds each. These are for additional canes to choose from for the next year's pruning.

The kniffen pruning system is similar to cane pruning, except the main trunk has two levels, one at a lower wire height, another about 30" above it. Often though, the upper level shoots are so vigorous that they shade out the lower level, not allowing the fruit to develop, so the kniffen system is not ideal.

Grape vines are vigorous and produce too many shoots. Some shoot thinning is usually needed to take out unproductive shoots without fruit clusters, and those that are too close together. The goal is to balance the productivity of the vine with the amount of growth.

Each grape shoot needs several well exposed leaves to properly ripen a grape cluster. If too many shoots are crowded together, they do not get enough light for photosynthesis. Thinning grape shoots eliminates unproductive shoots and provides light and space for productive ones.

Start thinning shoots as soon as possible -in June or as soon as clusters appear. Shoots are soft and can easily be removed by hand. If there is more than one fruit cluster per shoot, the lowest one (closest to the old cane) will usually ripen earliest. It is best to thin down to one cluster per shoot.

Training and tying the shoots up on the trellis should begin early, to maintain spacing and keep shoots from trailing on the ground or breaking off. Later, if shoots are long and vigorous, they can be cut back on the ends to prevent shading the lower vine. New shoots can emerge where a leaf joins the main shoot. These side shoots should be removed.

Just before harvest the lower leaves surrounding the grape bunches can be removed to provide better exposure to the sun to ripen them.

Hope this is clear enough and not too long winded!
Don't do this major pruning until fall though, as you will cause the grapes to bleed and possible shock. Hope you see tons of grapes next year!!
VAL (Grandpa's Rose)

[The Helpful Gardener]

That's yeoman's work Val!

Nice job!

HG

[grandpasrose]

Thanks HG!!
Sure glad to see you're back!
VAL

[CaptainK]

OK, it is a new growing season and I want to get things off to a good, and proper, start for these grape vines to see if I can get them to produce fruit.

The already have very small leaves on them at the moment. OK, what do I need to do?

Thanks,
CaptK