That is a nice writeup better than the one in Good Fruit Grower a while back.

Very good news that rootstocks can overcome replant disease as well as fumigation.

Supports my long term conclusion that soil can be too fertile even for apples. More organic mulch isn't better especially if one values eating quality over yield. The mulched treatment didn't even yield more.

Grass and a weed free strip is what I've used since the 70s. Now I'm using weed barrier but it's not better, just uses less water.

Thank you for the post, I am going to read it thoroughly. I have about 25 young trees and a few old apple and pear trees that are almost done. They produced nothing last winter, in fact I lost a few young trees because of the extreme cold. Hope it doesn't get that cold again.

My 2-4 year olds ( espalier) are under wood chip mulch now and are growing nicely and some have already topped out the uppermost scaffold at at the 6-7 foot level. The mulch is only 3-4 inches deep, and covers the entire orchard floor, just enough to keep weeds down and has been down for 2 years without replenishment

How old do you suppose the trees need to be before discontinuing the wood chips and allowing grass strip.

Mike

Mike:

The research was from day one. So you could convert now. A grass sod does wonders to slow down growth. The only reason to not convert to grass is if the trees aren't big enough to suit your needs.

Fruitnut ,the two best production methods, according to this article, is either mulch or herbicide strips. Mulch becomes a problem over time by overly stimulating trees (as I've discussed in the past on this forum) but it takes quite a few years- over a decade to become a problem, probably (a lot depends on the original soil which somehow isn't even factored in by the researchers quoted in this article).

It should also be noted that the research here was all done in a humid climate, which changes a lot when it comes to being able to control excessive vegetative vigor. In the west, I doubt mulching ever becomes a problem in terms of creating excessive vegetative vigor.

It takes trees a great deal of time to overcome the negative affects of grass and I don't think the researchers covered all the issues here. There is chemical warfare (alleopathy) going on between sod and the trees and perhaps the arms race just ends up being canceled out by adaptation. I don't think anyone is suggesting growing dwarf trees in sod, though. This may be about free standing, more vigorous trees.

Thanks Appleseed. I've saved this for future reference.

I grew M9 trees in Bermuda sod (6ft sod and 2ft bare) in Amarillo from planting. The trees grew fine and bore fruit at a young age. Vigor was about right for a 4ft by 8 ft spacing. The soil was a heavy clay loam. If I over fertilized with nitrogen it took about 2 yrs to get vigor back under control. Never once regretted the sod and most people call Bermuda the grass from he!!

The Amarillo soil unlike my current soil was slowly permeable to water and nitrogen. With my current soil I can leach out all nitrogen with excess irrigation. Excess didn't leach out of the Amarillo soil. I tried many times for benefit of increasing sugar in sugarbeets and it wasn't possible.

This Coming year I expect 90% of my espaliers to reach their top fourth tier scaffold. I had very few fruit this past year, I suspect because of the cold and the relative youth of my trees.

They grew like weeds without fruiting burden.

Based on what I see (and I am no expert) from bud formation, barring horrendous weather, I am in for some thinning work next year and it will be the first year I will be paying attention to fruit quality etc.

I will not disturb the mulch this year. Not much would have broken down over the last two year period.

Wish me luck.

Mike

Fruitnut, that seems to be confirmed by research described in the article. Only a narrow sod-free strip seems to provide irrigated trees all they need, although I wouldn't assume the research is definitive in terms of a wide range of rootstocks or even in unirrigated situations. It seems likely that the more vigorous the rootsock the wider the sod free strip that would be needed and if trees are dependent on rainfall, who knows? Here is what is written.

"Another complex experiment from 1991-1996 compared different strip widths and timing of herbicide weed control. The trees were Gala on M.26, with drip irrigation in a clay loam soil.

The weed-free areas beneath trees varied from none (a mowed sod) to 2, 4 or 6 feet wide.

We were expecting a big area effect, but we found no effect from strip width: Trees grew and yielded the same in 2-foot strips as in 6-foot strips of weed control. We think this was because the trees were drip irrigated and there were several dry summers during this experiment, so the drip lines concentrated apple roots where the water was.âÂÂ

This year my trees could have used more fertilizer. I didn't really give them much, just a small application in the spring. They grew well but I'm seeing some nutrient deficiencies. I need to get my soil tested see what is going on. Trees still grew well, which is what I want, as they are very young. I use pine straw for mulch. It is not going to create any buildup of nutrients, It is rather lacking in many. But will keep the grass and weeds away. I think myself the grass took much of the nutrients. I was lazy and should have put more pine straw down. The grass filled in somewhat. I have mostly bluegrass, it's as thick as grass can be and greener than green. A friend makes tree fertilizer and I'm going to run all results past him. He used to run a nursery too. See what he says I should do but first the soil test. If I ever find time to take samples!

Anyway thanks for the link. I'll stick to pine straw mulch and not worry about wood chips, or grass or weed killers.
At least for now.

" It seems likely that the more vigorous the rootsock the wider the sod free strip that would be needed and if trees are dependent on rainfall"

I think that's right, if you want the trees to fill in a decent sized canopy in a reasonable amount of time.

Interestingly, this year we did hardly any weed control for peaches at the house. Since the mulch has largely disappeared, grass/weeds were growing under the trees, right up to the trunks. Sometimes we chopped weeds to keep them from growing up through the canopy (We chopped weeds here at the house because I didn't want to risk killing peach seedlings under the trees, which I use for graft rootstock.) I wasn't able to discern the peach quality was any better, despite the ground being drier from weed competition and lack of mulch.

We still get plenty of wood chip mulch at the farm, but one thing I've come to learn is that an orchard floor can adapt and grow weeds in wood mulch. Field bindweed will make a thick carpet right on top of the wood chips. The worst thing is that bindweed is a perennial w/ a huge volume of root mass which competes w/ the tree. Bindweed is sort of like an iceberg, with little mass (relatively speaking) on top and a lot of mass down below. It has been demonstrated this root competition decreases brix in tomatoes. My guess is that it also does so in fruit. It would logically follow (in my mind) heavy competition of any weed would reduce brix, but I haven't read any research in this regard.

Why would root competition decrease brix? Seems to me it would be the other way around.

Bind week is horrible stuff. I've read that it is to organic wheat growers what plum curculio was to fruit growers before surround. It becomes financially untenable to grow wheat once this stuff is established, apparently.

It showed up in my vegie garden about 7 or 8 years ago and pushed me to use woven landscape fabric as much as possible. Species that can't be grown this way, like asparagus get weeded weekly and I still can't eliminate this weed from hell.

It's not such a problem on trees though.

Drew

Sent private email.
Wonder if you received
Mike

"Why would root competition decrease brix? Seems to me it would be the other way around."

I suspect the root competition interrupts key physiological processes responsible for packing carbohydrates in the fruit. Fewer carbohydrates would translate to less sugars.

Below is a power point about field bindweed in tomatoes. The bar graph on page 7 shows a very strong correlation b/t brix and the amount of time bindweed was excluded from tomato plantings.

Here is a link that might be useful: Field Bindweed Management in Processing Tomatoes

But bindweed climbs and steals the sun from the plants it occupies.

Agree with harvestman. That's a function of weeds shading the tomatoes.

"Agree with harvestman. That's a function of weeds shading the tomatoes."

That's true, but I also suspect root competition may play a role.

It goes back to the long standing debate on the forum about the effect of N on brix. In the past we've all posted lots studies regarding the relationship of brix and N. I don't think there ever was a consensus on the issue, in the studies or forum members.

For my own part, I believe the correlation is best represented by a parabola (i.e too little N, or too much N reducing brix, while max brix is achieved with a moderate amount of N).

I really don't want to start that debate again because I don't have time to Google up a bunch of studies again.

Nevertheless, weeds do compete for N (and other nutrients - which also may lower brix) as well as their potential allelopathic competition, which I believe can have an effect on brix.

A quick Google yields several studies of the detrimental effects of weeds on fruit crops, but most of these are w/ low growing crops (brambles, etc) so it can always be suggested the lower brix resulted from reduced light.

I did come across one study (of Guava) which indicated a strong correlation (i.e. more weeds = lower brix). I don't know much about Guava, but the trees seem to be about the same size as peach trees, and the orchards seem to be spaced about the same as a peach orchard.

However, even the study mentions not only do weeds compete for water and nutrients, but also for light (As I mentioned earlier, we chopped weeds last summer to keep them from growing up through the canopy here at the house.) So again, one could argue reduced brix from weeds is not a function of nutrient competition, but of light competition. An argument which can always be made because just about all commercial fruits are grown low enough to the ground to be affected, at some level, by light competition from weeds But again, my opinion is that reduced brix is a function of both (light and nutrient competition).

Here is a link that might be useful: Effect of herbicides and hand weeding on weed control in Guava

I'd say you've got it right, nitrogen can be both too low and too high for optimum peach production. You need enough for a full canopy of leaves and growth of new wood. But too much favors wood growth and excessive shading over fruit quality.

In the tomato example yield was cut in half by weed competition. Brix was reduced from 5.0 to 4.8, not really much difference.