Some things I don't understand about stonefruit brix

I’ve had experiences this yr similar to the past. Basically peaches just don’t achieve the high brix I’m getting with nectarines and pluots. In about 15ft of one row all watered the same and all on Lovell, brix has been:
Redhaven peach 13-14
Sweet Dream peach 18-19
Arctic Star 30
Arctic Jay 29.5

The peaches are way bigger. Sweet Dream several times the size of the nectarines. The nectarines can be very good sized and still have mid 20s brix if water is less restricted.

Basically the nectarines and pluots are much more responsive to restricted water than peaches. I wonder if it’s not the smooth skin losing much more water than the fuzzy peaches.


Interesting Steven. Have you collected data on size vs. brix for your stonefruit? I wonder if your low brix peaches would fall along that trendline.

Within peaches, do you notice if the peaches with less fuzz show an increased brix relative to the fuzzier ones under similar conditions?

This will give you some idea of what I’ve seen. Brix in nectarines above about mid 20s is where size really starts to drop. In general I don’t like the 30+ brix nectarines more because that’s where flavor can go bad rather than the small size. The mid 20s brix nectarines and pluots have great flavor and good size.

[quote=“bradkairdolf, post:2, topic:6281”]
Within peaches, do you notice if the peaches with less fuzz show an increased brix relative to the fuzzier ones under similar conditions?

Scott pointed out that Sweet Dream, 18.5 brix, is a half fuzzy peach whereas Redhaven, 13.5 brix, is quite fuzzy.


Looking at that picture, I’d choose the 22 brix piece in the upper left :slight_smile: This is reminding me of the “how ripe do you like your bananas” thread.


The difference between upper two rows and the smaller, higher brix fruit below isn’t ripeness. The bigger fruit you might find in a store. The smaller fruit was better IMO, sweeter and more flavorful.

The smaller fruit look a lot less firm. Like with bananas, I’m willing to forgo some flavor and sweetness for firmer texture.

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I see what you are looking at. I prefer mine soft ripe. That’s when they have the most flavor. But these low acid nectarines, big little high or low brix, can be eaten weeks before they turn soft.

Thanks for the photo @fruitnut.

That’s an interesting theory, but it doesn’t explain the huge differential in brix of various nectarines I grow here, where last year Honey Royale had close to double the brix of my other nects- however it had a tiny crop. Funny though, I did not prefer it except that it tasted so unusual. No off flavors, just a lot sweeter than I’m used to peaches or nectarines being.

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@fruitnut I have been thinking about this phenomenon that you have been observing, and I wonder if it could be less photosynthetic activity in the fruits (of peaches) themselves. I know that photosynthesis occurs mostly in leaves, but if fruits have green color, then they contain chlorophyll, and if they contain chlorophyll, then they undergo photosynthesis. I think the fuzz deflects some of the light away from the fruit and hence peach fruits undergo less photosynthesis than fuzzless nectarines and pluots. The issue is probably exacerbated in your green house, because the light intensity is less than under direct sunlight.


That could have some effect. It could also be that there is more water loss from the skin of nectarines. But I don’t know that either would have any real effect. It could also be that nectarines are just genetically disposed to have high brix.


Different varieties just have different soluble solid levels and even those with similar brix levels can have much different apparent sweetness due the make up of sugar and sugar like compounds (glucose, fructose, sucrose and sorbitol for the most part) and also the titratable acid levels. We grow about 15 different apple varieties and amongst those that all ripen mid season around October 1st they range from about 16 (Jonagold) to some French cider varieties that are nearly 30 some years.

We don’t grow a lot of varieties of stone fruit, but our Royal Anne cherries are about 20 brix and ripen at about the same time as Van’s which are about 30+. Our peaches and nectarines range from 15 to low to mid 20s. The odd thing is that the first peach variety has the highest brix and the last variety is the lowest. This is the opposite of our apples which generally the later ripening varieties are higher. Also as far as pluots go, from my understanding they are bred to have as high as possible brix to please sugar loving palates.

I actually can’t really eat high brix cherries because they tend to burn my mouth. Somewhere around 22-25 is my preference depending on acid levels. However, our customers adore the Van’s and are more ambivalent to our Lambert’s which have a much better balance to me. To each their own though, which is why we try to grow a decent number of varieties to please different palates.

I’m actually much more accustomed to ripeness indicators in wine grapes though. Harvest decisions are made by a pretty complex matrix of factors including brix, TA, pH, tannin, color and seed ripeness, because flavor is much more difficult to determine. Hotter areas will grow much high brix fruit, but this is not always a desirable factor because the brix levels and thus the resulting alcohol levels can get much too high before flavor and color ripeness are complete. And even some varieties in some vineyards we would need to get harvested based on pH because it would get way too high which cause all sorts of problems in the winemaking process.


Given the wide range of brix within the varieties of nectarines I grow, that would seem the logical main reason for variance. Evanfall also offers clear evidence to support that analysis. However, with cherries I have to assume he is also weighing in relative crop load to leaf ratio. Cherries can overbear and I assume that affects brix as well as size. For some varieties it is more a problem than others.

Yeah those brix numbers come from trees with at least somewhat similar cropping levels. Most of my brix numbers for all our varieties came from adding them to cider and only use excess fruit, so I tend to only get numbers in heavy years. Other than apples anyway, I do have pretty extensive data on those. It can vary quite a bit year to year, but every variety has a range that it sticks to.

Oh also, most tree fruit varieties brix do not correlate well with degree days. In grapes a hotter year=higher brix as long as there is no rain around harvest time. Apples however, our hottest years 2800 GDDs have brix levels similar to years around 2200 GDDs. Rain near harvest can water down the fruit though.

The bane of my fruit growing existence. I’m guessing from your brix numbers that your growing season doesn’t include a lot of rain- although 16 for Jonagold isn’t impressive. Do you grow Jonaprince? It seems to get higher brix here than other sports I’ve grown. It’s actually somewhat difficult to distinguish between a high quality Honeycrisp as grown here.

As far as rain, I believe that the grey skies that accompany it are at least as important. This I can assume having orchards I manage that are in turf that is watered every other day.

I’m thinking it is a bit of a 1-2 punch, because I also seem to get superior fruit form sandier soils that drain out and become dry quickly. The problem is that anecdote does not research make.

Willamette Valley, Oregon, so we can have a bit of rain :smile:. However our cherry season is bone dry. Our Jonagold are usually 16-18, looks like Jonaprince runs about 1.5 to 2 higher usually? Jonagold are the lowest around their harvest period though so they may do better elsewhere. I’m not a huge fan of them though, a bit bland off our trees. They come on just after Akane which is one of my favorite flavored apples and at the same time as Empire which also has much more flavor. Both of those varieties have much more berry and dark fruit flavors, while Jonagold tends to have the vitamin c punch that I also get from Golden Delicious. Funny enough, Honeycrisp is also one of our lower brix varieties, but I don’t use it in cider at all so I don’t have as much data on it.

Oh I’m also taking samples of juice from 1000 pound batches and with a hydrometer. Refracts tend to vary from hydrometer reading. They probably vary consistently enough to just use different alcohol conversion rates, but I’ve just always used the hydro number and get good estimates. Spot samples will tend to be a bit higher than whole crushed fruit readings as well. In grapes wildly so, we’ve had growers become very grumpy when we tell them that their field reading are way off.

The other thing about sandy and rocky soil, at least in grape growing regions, is that more heat is released at night into the canopy and does increase brix levels. Whether this is from respiration at night or from raising the temperature in the morning or both, I do not know. I would imagine bare soil reflects light back into the canopy as well since grass only reflects back unusable wave lengths. This is just a guess though and would depend on your soil color as well. There is plenty of research on plastic mulch color, but I’m not super familiar with the results.

I would suspect that more water in it would make soil hold more heat during day to release more at night- but that is just theory, I assume your belief is based on more.

Your rain season tends to only marginally encroach on your harvest season, right? I was raised on the west coast. In my part of NY we average between 3 and 4 inches of rain every month of the year. April has already surpassed that.

Depends on the year, last year we had a deluge right at the end of apple season, everything left on the tree swelled and split wide open. During the summer it’s odd for us to get a single inch of rain though.

I can’t be sure the soil heat thing is fact. It’s what has always been said about very rocky vineyards. It shows up in scientific literature, but I haven’t seen hard data. Chateauneuf de Pape and rocky areas of southeast Washington definitely have riper wines than surrounding areas, but there could be other factors in play as well. Also darker soils heat more quickly in sun light, but then they should reflect less light back up. Then also, if roots get too hot, the plant may shut down photosynthesis. There’s probably so many factors at play, and maybe there’s literature comparing all of them, I haven’t searched for it though.

Do you grow any Spitz for eating or for cider? High brix and high acid as well as good annual production here. About my fav antique. I know there are some who grow it quite successfully in the West.

And King David? Newtown?

Yeah we have Spitz, flavor is great, but production is really weird. We thin heavily but still have very light years about one out of every three. The other problem is that it has a pretty low juice yield. Around high 50s% yield vs close to 70 for other varieties. We’ve actually found a few varieties that are not often recommended for cider are our favorites. Gravenstein makes a nice dry, reasonably tannic and rustic cider. Akane yields nicely and has a spicy strawberry and citrus flavor. And something we were told was “Rome” when we bought the farm 30 years ago, I’m not convinced that’s what it is, but usually gives about 11% alcohol and has really rich baking spice flavors. Jonagold is often recommended for cider amongst eating apples, but again it’s a bit boring from our orchard. Cox Orange Pippin is of course excellent as well, very mango/tropical flavors, but again really bad juice yield. We also have a fair amount of cider apple varieties, but I actually prefer the eating varieties. My thoughts are that the high tannin cider apples need a fair amount of sugar in the cider and we do all our ferments dry.

No King David and no Newton. I’m going to be grafting a lot of the very old orchard next year and will be adding Ashmead, Golden Russet, more Cox, Ribston Pippin, Pinova and some others. So I might add Newton as well.

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