"It is very difficult for establishing fruit trees to compete with tall weeds- 3 options- frequent cultivation, mulch or herbicide. Keep at least a 4' diameter circle free of grass and weeds at least from early spring into July."

First, a couple questions about keeping down weeds. H'man, you talk about difficulty competing with "tall" weeds, but you don't mention mowing as any kind of option. What's the usefulness and what are the limits of mowing when establishing fruit trees?

As far as cultivation, what are the options there? Does that mean hand weeding? Rototiller? Any other cultivation options? I'd be afraid of the damage I'd do to my tree roots from rototilling.

And what about flame weeding? Would that be another option? Anyone use flame weeders around his trees?

I moved to where I live in the fall of '07 and immediately started planting trees, so after nearly 5 growing seasons I'm starting to notice some big differences between trees in vigor and growth rates, and I'm wondering how many of the slow growers can be explained by my failure to follow H'man's advice above.

Trees that have grown very vigorously for me despite minimal attention to weed/grass competition include:
Chinese chestnut
mulberries
European and Asian pears (on whatever Hidden Springs uses for rootstock)
figs
European plums (except that I planted them on the N side of a building where there isn't as much grass/weed growth)
chickasaw plum
peaches
jujubes

Trees that have had growth that seems normal and healthy but that don't seem as vigorous as the group above:
mayhaws
azarole
some apples (stayman, limbertwig... M111 stock)
sour cherries
Italian stone pine

Trees that seem healthy but have grown very slowly:
pecans
other apples (Arkansas black...)
Meader persimmon (although it seemed to finally catch a good growth spurt last year, year 4, but was hit twice by hard freezes in early and late April this year)

Trees that look stunted:
Gold Rush apple, Liberty apple
or appear healthy but haven't hardly grown any in 5 years:
pawpaws

As I've often mentioned here, I like to use a thick layer of arborist wood chips as a mulch for establishing trees. The old fashioned technique was to use a hoe to keep herb-free rings under establishing trees. Commercial growers conventionally use herbicides to keep the earth bare in row middles, even for mature trees and organic growers often do shallow rotary hoeing to eliminate weeds in row middles.

As I understand it, the taller the weeds the deeper the roots and the greater the transpiration created above ground, pulling water and nutrients out of the soil, so mowing, the lower the better, should decrease competition.

Even if your trees establish with vigor in the face of competition they should do so even quicker if that competition is decreased.

I've no experience flaming weeds but I've no reason to think it wouldn't be affective.