losing this year's crop

[susieqz]

when i mentioned my unknown vine. i told you i expected a full bushel. of grapes.
these are supposed to be large grapes/
they are a pretty purple when ripe.
i assume they don't get bigger once they change color?
mine are as big as medium blueberries or smaller.
i've been eating some. just sweet enow for out of hand, with no juice.
oddly, once i finish some, there's a bitter burn at the back of my throat.
i think there are undeveloped seeds in them.
so, yield is small.
what did i do wrong?
i'm not even getting a small crop. many bunches are turning into raisins, even tho still green.
it looks like wasps are draining the juice out of them. does that happen?
i can eat these fresh, but there is little juice in them.
i'll never get wine from grapes like this.
i guess i'll throw some skins in welch's juice, to try to get some kinda wine.
but, i'm hoping someone can tell me how to get a normal crop next year.
please?
did they get too little water or fertilizer?

 

[FrontenacMan]

Hi Sue,
If Google Maps is showing me the correct location in your profile, you are in Wisconsin in my neck of the woods. I've lost some of my grapes this year to Black Rot. I've got four year old vines and this is the first year that this has happened. Black Rot will turn your grapes into raisins. It is a fungus that releases spores in hot wet conditions and usually happens during bud break which is when your grapes and vines are most susceptible. You will also see brown spots on the grape leaves and black spots on the new canes that have grown. This year we had an unusually warm wet May and June. Unfortunately I didn't know much about Black Rot until it was too late as I have not had problems with it in the past. It is very important to keep your canopy open so that air flow can keep the grapes and leaves dry and prevent the spread of the Black Rot spores. But that can be difficult when you have the high amount of moisture we have had. It's also important to cut out any "mummified" grapes because they will keep the spores over winter and then release them next spring. Also when pruning make sure to keep your shears clean as the fungus can be spread this way as well. I've heard Clorox wipes are one way to disinfect your shears.
You're grapes are probably pretty much toast this year but hopefully this will help for next year. You can also use a fungicide to help control it. I've also read that when pruning infected canes you can mix some cinnamon with vegetable oil and apply it to the area to keep it protected. Hope this helps.

 

[susieqz]

thanks tons, fron.
i'm in new mexico on the high plains but black rot sounds likely.
i'll go trim those vines.
i suspected wasps because they were at the scene but that's all.
i should have had a big crop, but between the small grapes n the rot i've lost most of it.

 

[FrontenacMan]

Yes, I understand your frustration but don't lose hope. One thing I've learned and any farmer will tell you is that with any growing venture, there's only so much you can control and the rest is up to the plant and the weather. Two years ago we had a late frost at the end of May. I have a small garden vineyard so I was able to cover my vines based upon weather forecasts and save my crop. But a local vineyard even with fogging equipment running all night (something called a "dragon") lost 60% of their crop to the frost. Sometimes there's just not a lot you can do. Grapes are pretty resilient though. They'll bounce back.

 

[susieqz]

um, do you have any ideas about small grapes?
i pruned about half the bunches before the trouble started.

 

[ibglowin]

I find it hard to believe it would be black rot. That is a fungal disease and you (and I) live in a very dry desert state with not much in the way of rain or humidity for that matter. I have been growing cold hardy grapes in northern NM since 2010 and we have monsoonal moisture in the Summer months and I have never had any disease on my vines, not even one Summer we had record monsoonal rainfall. My guess without any picture to look at would be a lack of enough water especially if the vines are young as well as fertilizer. We have shat for soil her in NM and grapes need a lot of TLC to grow here.

 

[susieqz]

thanks, ibg.
i wondered if it could be water.

 

[FrontenacMan]

What I know of fruit size is covered under a topic called fruit set. It is the process when the flowers turn to fruit and there are several factors that contribute to/affect this process. Water is certainly one but there are many others. Here is a link to a description of the process and determining factors - https://www.lodigrowers.com/improving-fruit.set/

 

[susieqz]

great site, fron.
i had no idea that fruit size is determined at the flowering stage.
i'll try some fertilizer plus extra water at flower time, next year.

 

[FrontenacMan]

Just be careful not to make drastic adjustments. Again weather conditions play a role. And from what I've read, grapevines being perennials develop memories from previous growing seasons which carry forward to the next season. So some of the activity in the current growing season may be due to factors from the previous year. Consistency in management is key. In my case with black rot, I'm pretty sure some of my problem was due to not removing some late developing clusters on my vines that did not ripen. They apparently are a haven for black rot spore over the winter. I also think I will need to develop a consistent preventative spraying regiment early in the growing season and closely monitor moisture conditions to keep fungus levels in check. In your case and where you are located as Mike has said, that is probably not an issue as much as irrigation management.

 

[ibglowin]

I am located at 6600ft EL close to Santa Fe. I find that vines flourish well here with 2G every other day (drip) and fertilizer about every 2-3 weeks through May and June. I have had a light case of powdery mildew that is not bad enough to hurt the grapes or vines but this is only on a couple of vines that are in the direct path of my underground sprinkler system for turf grass. These vines get hit by water spray every other day for like 40 mins and still we are dry enough that the mildew can't really establish well at all. If you are over by the TX border you are close to the "dry line" between the dry NM desert air and moist humid TX airflow so while you are not exactly 100% like me weather wise I would think you are still pretty dry compared to TX.