http://fruitgrowersnews.com/index.php/magazine/article/Keeping-Under-Cover-The-Ideal-Look-of-an-Orchard-Floor

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.

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

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.

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.

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.

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

"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.”

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.

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.

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.

Sent private email.
Wonder if you received
Mike

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.

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).

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.