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Increasing Brix in the vineyard

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dwhill40

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Hello Grape Gurus,

I'm trying to figure out why the Brix on my red vinifera refuses to get beyond 20 Brix. I was able to get some great hang time this year and still my main Cabernet crop was around 19 Brix. In the same small block I grow Petit Manseng and it hit 23-24 Brix and probably could have hung another couple of weeks. The Cabernet wine is awesome, fruity with a touch of richness, the acid is stout yet soft after a three day cool soak and a week of fermentation. PH was around 3.41 after crushing . The grapes ferment like mad as soon as hydrated yeast hits them and the color is glowing red. So I don't think I'm missing any good stuff in the grapes. I have been very sparing with fertilizer yet the vines grew well this year so I do have enough little solar panel leaves out there working. I have a couple of months before cold weather so I'm going to try a post-harvest fertilizing this year with black cow and organic fertilizer in the row middles. I planted in 2013 and have never used chemical fertilizer. Any ideas of why the Brix on my Red grapes stop near 20 Brix?

Thanks,
 

salcoco

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first thought is growing period not long enough second thought not enough sunshine reaching grapes.
 

Snafflebit

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Knowing your location would help. The best way to know what grapes are suited for your climate is to determine your Growing Degree Days. You might be able to find a source online that calculates it for your location. Or you can attempt to use a spreadsheet and some weather data. Cabernet Sauv is a late ripening grape, and likes about 3000 degree-days for ripeness.
 

ibglowin

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That was the hidden joke in my response. His IP is coming from Alabama......

Knowing your location would help. The best way to know what grapes are suited for your climate is to determine your Growing Degree Days. You might be able to find a source online that calculates it for your location. Or you can attempt to use a spreadsheet and some weather data. Cabernet Sauv is a late ripening grape, and likes about 3000 degree-days for ripeness.
 

dwhill40

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Yeah, sunshine in North Alabama is ample. Believe it or not we missed most of the rain. My vines are in an odd micro-climate where t-storms dissolve then reform on the other side of the plattue. But, we didn't miss the cloudiness. I did discover the capabilities of well established downy mildew last year. I found agriphos and captan will recover a defoliated vine. Maybe that reduced the carb stores? But, I've seen the same results for several years. The brix has never gotten to 21. I should also mention my subsoil tests at PH 4.9 and there is no amending that without remodeling the place. I distribute ample gypsum to bind up the toxic chemicals and the vines look perfect. I think it is a vine physiology issue since the petite manseng brix was ample.
 

salcoco

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plenty of daylight sunshine but how much getting to the grapes do you follow any leaf pulling efforts. grapes could be in the shade especially the backside of the cluster and thus not getting as ripe as they should.
 

dwhill40

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Yeah, I have to shoot thin a couple times and keep the fruiting zone pulled or the canopy literally becomes a canopy. I think I have a carbohydrate production issue. My soil test comes back as topsoil and subsoil is sand. I'd call it a sandy loam and sandy clay but the University categorized it as sand. I can grow vinifera varieties on their own roots and have for 7 years. Phyloxera can't motivate in sand. I have two small blocks on differing sites but both are almost hundred year old fescue pasture which has to be "washed out" thus the low PH. The brix issue occurs on both blocks with different varieties of red grapes. I may be missing carbon or the uptake of carbon? I downloaded The Science of Grapevines. Guess I need to keep reading.
 

pproctorga

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Having tried growing hops in Georgia I know that we don't have the sunlight of the prime growing areas in the northwest. We're lucky to get 20% on the muscadine grapes here. I know that their brix was down this year due to so much rain... 15-16 brix. I have a Cynthiana grape vine, among many others, that I planted a few years ago and had its first great production year. This grape has similar characteristics to Cabernet Sauvignon that I hope holds promise for my location. This year it hit 20 brix on the ripest of the grapes, but this was a year with a lot of rain so I let them hang as long as possible. The advantage of the northwest is being semi-arid, which allows them to add water when its best. They also have hot dry days to finish off the grapes and concentrate the sugar levels.
 

dwhill40

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Now that is an interesting point I'll have to investigate. I've noticed the UV index here can be listed as average on a 95 degree day as the humidity can affect UV intensity. I often tell people North Alabama is the same latitude as the Sahara and it blows their mind so it is difficult to imagine the amount of light being an issue but the Gulf of Mexico shoves clouds through here on a conveyor at times for weeks on end. This year was odd with fruit trees and the garden not growing/ripening normally. We (earth) are in a grand solar minimum as well so things can get stranger yet. I don't mind throwing in a little sugar to bump up the brix a couple of points as long as I'm not missing some soil amendment. Thanks!
 

Rice_Guy

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. . . but this was a year with a lot of rain so I let them hang as long as possible. The advantage of the northwest is being semi-arid, which allows them to add water when its best. They also have hot dry days to finish off the grapes and concentrate the sugar levels.
I haven’t hunted the article to look at what the limiting details were, but there is some research saying that the tail end increase in Brix is due to loss of moisture
 

Snafflebit

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I haven’t hunted the article to look at what the limiting details were, but there is some research saying that the tail end increase in Brix is due to loss of moisture
this is true, but it usually applies to a Brix in grapes above 25, meaning the grapes have reached full physiological ripeness. Brix of 20 does not sound ripe to me.
 

dwhill40

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The phenolic ripeness is on point. The peduncles on most clusters were brown and the seeds were brown-ish and would crack when chewing them, The color is like blood and the tannins are stout.. After reading up on nitrogen reserve pools and uptake, I'm going to have to look at fertilizing with a slow release nitrogen after budbreak as well as a small bit after harvest. I may be sorry because of the vigor but a little won't hurt... The Lyre canopy could be shading a bit much as well but I'll know that next year.
 
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