I prune stone fruit in the greenhouse regularly during the summer. But if done before harvest it is only to control tree height. I prune at around 8.5ft. When it hits 10ft it gets cut back. Major pruning is after harvest.

My situation may be unique in that if I opened up the tree and thereby lowered light interception, the reflective ground cover would reflect that light back into the bottom of the canopy. So it's all about maintaining enough photosynthesis to sugar up the fruit. I'm very concerned about leaf to fruit ratio or however you want to express the situation.

My trees seem able to sugar up a great deal of fruit so they must have enough leaves. I also think the light environment in my greenhouse covered with IR poly that diffuses light plus the reflective ground cover results in outstanding light in the canopy.

Other management factors seem more important in my operation, namely water management. But I've decided that I may be approaching that subject from the wrong angle. Instead of saying the trees need moderate water stress, I think I should say the trees need deficit irrigation. Water at about 75-80% of full water use and the fruit will be sweeter and more flavorful.

Sorry if I've taken your thread off track already.

Pruning to allow better airflow and sunlight on most fruit is generally a good idea. The advice you are pointing to might be specific to early peaches. With my early peaches (that finish in May) it is much easier to just wait until after harvest to start pruning.

Can't cite any research at the moment, but I've read summer pruning decreases fruit size. For that reason, I've been reluctant to summer prune much before harvest.

I've been leaning toward doing more dormant pruning on peaches in the Spring anyway. The article you reference above, plus the one you posted the other day are a couple more reasons to head in that direction.

The other reasons would be less thinning and less risk of canker.

OP, according to the article I sited, the negative affects don't occur if you wait until 30 days before harvest. If peaches are growing vigorously (as I know yours do) summer pruning supposedly provides higher quality peaches with better color.

I've gotten in the habit of doing more summer pruning so that I've got something skilled to do while I have help thin fruit or set up squirrel protection on sites I manage. I start about 2 weeks after my second Imidan ap.- usually about mid-June here.

Because I am going very low spray on the fungus, I like the trees pruned to let light and air on all the fruit and I suspect this is one reason I often get away with only one Indar ap.

I like to keep the apples pretty open as well, to reduce summer fungus.

I think I'll experiment with single trees, pruning and not pruning the scaffolds different ways.

Does anyone know the relation between a single growing fruit on a tree and the particular leaves that are "feeding" it? I vaguely recall that leaves far from a given fruit are not feeding that particular fruit. So, pruning long shoots that are far from any fruit at the ends would only seem to have a positive effect of giving more light to the leaves by the fruit. Even if leaves anywhere on a tree could help any fruit there is probably some kind of decay with distance, so removing those far leaves and and thus allowing more light into the near leaves will always be a win. I know that CA grape growers, who are way ahead of the rest of fruit growers on the brix issue, now regularly hedge vines in summer to obtain the best quality.

Anyway whatever the answers to the above I think you need to look deeper than just summer prune or not, you also need to look at which particular leaves are being removed, how much they block which other leaves, etc.

Scott

Does anyone know the relation between a single growing fruit on a tree and the particular leaves that are "feeding" it?

Scott, the link below discusses this. It's a great article by Richard Marini, and from time to time a re-read it as a refresher.

While Hman's orginal post was relates to brix, and Marini's essay relates to size, obviously there are some common denominators between the two.

Marini points out that auxiliary shoots as well as primary fruiting shoots affect the size of peaches. So by pruning auxiliary shoots it could affect the fruit size even though no peaches are on those shoots.

However, I do agree things like new water spouts probably aren't contributing anything to the size of peaches and are better trimmed anytime their observed.

As both you and Hman observe, the article also points out the importance of light in the canopy, but suggests pruning for light within the first 40 days after bloom since at this time peaches are being fed by energy reserves in the tree and not by the foliage.

The article doesn't mention pruning the last 30 days before harvest. However, it possibly makes sense to me that pruning the last 30 days doesn't have a detrimental effect. At that point any weight gain is mostly water anyway.

That said, I doubt I'll do any pruning the last 30 days. Trying to selectively prune while there are large peaches on the tree takes extra labor. I figure if the peaches are that close, pruning can probably wait till the fruit is picked. That way you can get in there and really chop some wood out of the canopy.

Trees that harvest too late to prune after picking, I'll probably still continue to prune at bloom for thinning and canker reasons.

Good discussion.

Here is a link that might be useful: Big Peaches

Scott, I was hoping you'd chime in here and I wonder about the same things you bring up. However, the grapes are grown where irrigation is controlled, so the affect of having more root in ratio to the top can be easily controlled. Reducing water has the same affect as reducing root.

The reason I think that brix might be affected by removing shoots not actually feeding fruit is simply about this balance which would be the same for all practical purposes as giving a tree too much water and N which we know leads to big tasteless fruit.

Root pruning is not much practiced in this country, but I gather it is still a tool in Europe and elsewhere. I wonder if it is used in conjunction with summer pruning.

OP, if the peaches are being fed by reserves why would you prune within those first 40 days as the light would not be helpful at that time?

Actually many of the practices that reduce size increase brix, including root pruning and deficit irrigation.

In most fruits and vegetables, fruit or vegetable size and cell size in that fruit, are negatively correlated to sweetness. The primary factor that kills sweetness in carrots and sugarbeet is excessive nitrogen and to a lesser extent excess water. In my experience the same holds true for fruits. Excess water and nitrogen leads to bigger cells and lower brix.

Maybe the commercial grower comes out ahead dollar wise with big bland fruit, but that's not what the homeowner wants or needs. And if a grower is selling retail I'd think he'd be better off thinking a lot more about eating quality than fruit size. I've started selling some retail. All I think about when I head to the farmers market is, what does my fruit taste like today.

Lowers brix? My best guess is that the tree then turns its energy toward healing the wounds and away from producing fruit.

I might try some summer pruning on my peaches and apricots, but it will be after the fruit is harvested.

"OP, if the peaches are being fed by reserves why would you prune within those first 40 days as the light would not be helpful at that time?"

Hman,

It's not that pruning the first 40 days helps peaches at that time, rather the idea is if one needs to open up the tree for light, it's best to do so the first 40 days when the peaches are dependent on root reserves for growth and not dependent on foliage.

"In most fruits and vegetables, fruit or vegetable size and cell size in that fruit, are negatively correlated to sweetness."

Fruitnut,

As I mentioned there are some common denominators affecting both brix and fruit size. I sure you'll agree fruit on the outside of the canopy is both larger and sweeter, while fruit in the interior is smaller and has less sugar. Similarly fruit with the right amount of foliage to support it will be larger and sweeter than fruit with too little foliage (i.e. un-thinned fruit, or fruit with thin foliage due to disease).

The principle for these common denominators is the same. Optimum management of the foliage packs the fruits with carbohydrates that both convert to sugar and add to fruit size.

I agree the commercial practices of excess N and water increase fruit size at the expense of quality, but I think correct foliage management will head both fruit size and sugar in the same direction.

I completely agree "when I head to the farmers market is, what does my fruit taste like today". At a farmer's market, quality has to be foremost. I'm sure you'll do well.

I don't think "seriously". At least not in my experience.
I haven't done any actual tests to pay attention to when I pruned or exact brix year to year but the specific gravity is always around 1.050. Since I don't have a weather controlled greenhouse I couldn't do any actual scientific testing to rule out environmental differences.

As far as size, thinning and all that. I intentionally left all mine overloaded last year. I got some big apples, some small. Overall harvest was much larger by weight (big or small doesn't matter to me since almost all goes to cider but I do want high average sugar) and the sugar content was right around 1.050 just like always.

I think a lot of these tests are a bunch of quibbling over minor numbers to get more grant money for testing.
If my apples ever lose or gain 10 points I'll be trying to figure out why, but a couple points either way is yearly variances that could be a lot of things.

OP, thanks for the article link. I will have to start pruning peaches next week and it will influence my technique.

I never can wait until spring to prune peaches because I'm just too swamped by then. Never have a problem with canker anyway.

Olpea, thanks for that interesting link. When he is discussing why the interior fruits are smaller he hypothesizes it is due to fewer leaves right by them, as well as less light. He also suggests summer pruning in June to let more light in to the interior.

Overall, I don't think summer pruning close to harvest would be a detriment as long as the leaves pruned away were away from any fruit, and the pruning brought more light to the leaves by the fruit - the fruits are losing energy from afar but gaining more energy by the fruits than they lost from afar.

Scott

Scott, the article I have suggests that as long as you wait until late in the season- 30 days before harvest- and don't remove shoots near fruit, you get better color (which may mean higher brix) without any down side.

One of the points to summer pruning that has always been my primary motivator is mentioned in OP's article and is to keep bearing wood low in the tree. Without summer pruning, peaches can become sprawling and inefficient with higher and higher branches. Or the shoots you're left with lower in the tree are weak and not conducive to producing the best fruit.

OP, the one issue you might want to consider not mentioned in the article on big peaches is that sometimes if you've had a harsh winter it will be the smaller shoots that have the surviving flower buds. This might be a good reason to wait until bloom to decide to prune for largest fruit.

Hman, I was indirectly opining that I don't think there would be any negative to pruning even within the 30-day window as long as you were away from fruit and by the summer pruning were getting more light to leaves that were by the fruit. All of these notions are somewhat fuzzy of course. I have some peaches and plums that are shooting skyward and I am hitting those top shoots many times in the summer. They are very far from the fruiting region of the tree and I am getting more light into the fruiting region by topping so I think that is always a good move independent of harvest date.

Scott