Mycorrhiza - How often do you apply it?

Fall 2005 our tree care arborist recommended that we have the entire yard and gardens innoculated with mycorrhiza. The coast for a 70 x 140 lot chock full of mature oaks and loaded with ornamental beds and smaller trees was $475.00. It took two applicators the better part of five hours. I believer the stuff does have a beneficial effect. He wanted to do the same fall 2006. I declined. Right or wrong? I did buy some mycorrhiza from Gardeners Supply and incorporate in all the new 2006 plantings. It just seemed to me that this need not be a yearly thing. After all I am not farming and harvesting a crop.

http://cropsoil.psu.edu/sylvia/mycorrhiza.htm

From everything I've read and from lectures I've attended (CENTS show, usually OSU but sometimes other professors and soil scientists from the USDA and elsewhere), treating for mycorrhiza is tricky and probably redundant. There is a lot still to learn, and lessons are coming fast, and to be honest, I'm not fully up to date. However, this is what I've learned. Getting the mycorrhiza inocculant for the right trees is hit or miss. Some mycorrhiza work on many tree species, some on only one. Some trees host many mycorrhiza, others only one, or none at all. So paying for and receiving the right mycorrhiza for the trees you've got is important and sometimes difficult. I think the sprays arborists are selling are very general, containing several broadly hosted myccorrhiza species.

Moreover, in any decent soil, the right mycorrhiza will automatically and easily find the right tree species, especially (and perhaps exclusively) native trees in native soils. In really badly stripped off subsoil in brand new neighborhoods, a jumpstart with a mycorrhizal spraying, or even just application of a good quality compost or manure, might help these partners find each other, but usually they manage to do so just fine.

There is plenty of speculation that some very difficult exotic tree species might be difficult because they are trying to make it in a foreign land without their myccorhhizal possey from the hood, and this might apply to difficult natives like Mountain Laurels outside of their native soils too, but who knows? The study of mycorrhiza from a horticultural point of view is very, very new. Lots still to learn.

In the meantime, if your soil is good and your trees are okay, I think you are wise to wait on more applications. The other thing you might do, now that I think of it, is check with you extension agent for their advice. They are probably a little more up to date on this, and certainly would be more familiar with your local situation.

Scott

Good advice decumbent. The application I did get was ground injection of a dry material - lots and lots of injection holes on a grid basis throughout the area. In addition to stuff from Gardeners Supply I also purchased supposedly "tree specific" mycorrhiza from www.treehelp.com for a newly planted weeping Higan.
I will be seeing the local extension agent March 2nd at a gypsy moth public meeting about spraying Gypcheck. I am the local government coordinator for the spray program. The first question won't be about Gypchek! We have to use Gypchek instead of Bt because we are home to a population of Karner Blue and Bt is non-selective. I digress.

While I have a good working relationship with the tree guy he does have payroll to meet and he couldn't produce any literature that backed up his claim that annual repeats were necessary.

Talk of money-wasting overkill! The mycorrhiza is a living, growing fungus and will spread through the soil quickly. Also, if a particular mycorrhizal fungus species is suited to the tree, you only need to do it once; the fungus is perennial and remains associated with the tree for the rest of its life.

Looks to me like the arborist is more concerned about his income, than your tree's health.

Resin

Since no one said it above...take decent soil samples and have them professionally analyzed to see what your mycorrhizal species and levels currently are. OSU and the state cooperative extension service should be able to set you right up.

If you are living on soils that haven't been severely disturbed (and have successful healthy mature trees extant), you've probably given away enough money already. A soil test will be cheap in comparison.

As Scott noted: you really don't need to worry about such things unless you are trying to coax growth out of something pretty rare that ain't from around northern OH.

VV, does Enkianthus count? I've got a couple of dwarf ginkgos, two Abies fraseri and a Tsuga canadensis var. pendula
too. The weeping hemlock thrives (25') but the fraser firs I think could use a Ph drop. Mine is 6.5 and I think they like 5.5 better. Although they are twenty years here I have seen nicer ones. Really, I was worried about the oaks (Quercus velutina). We have had some significant droughts that did take a toll. The soil is relatively undistrubed and we have lived here 30 years. At any rate, I will keep my money in my wallet next time the tree guy brings it up.

OK, snapple, you're bombarding us with mixed messages now. Here's what I believe, based on your last post.

•Enkianthus (as well as all the others noted) are NOT native to northern OH area, but that still doesn't mean a mycorrhizal treatment was needed.

•Soil pH is not going to be changed by mycorrhizal additions (but nutrient uptake by plants may be affected). Soil pH affects which mycorrhizae exist and thrive.

•If the black oaks were already there on the existing soils, then additions for them are not particularly necessary either. Black oaks are among the most drought tolerant oaks, though they probably don't mind some moisture help during an extended dry period. Again, mycorrhizae and pH changes aren't making a difference in that aspect.

I still think the soil analysis would be a worthwhile investment. We could all learn a thing or two at your expense.

Here's a good general primer and explanation of what the heck mycorrhizae are and what they do.

http://www.californiagardenclubs.org/html/mycorrhizae.html

VV, Apparently I failed to convey two points. One - I believe that the fraser firs state of health is due to a less than preferential Ph and not connected to mycorrhizae. Two - I do have a nonnatives.
The oaks have been here for at least 55 years and probably much, much longer based on their size and they are most definitely native. They may be draught tolerant but I can assure you they will show signs of stress. The entire geographical area did. I appreciate the link. I'm happy to have anyone learn at my expense.

Snapple,

Do I remember you also having wicked flooding within the past year or two also? Perhaps even twice? I thought it was you..someone in N. Ohio. That along with a prolonged droughts (or two), could be the one-two punch combination that has your oaks reeling. Sometimes long, wet periods lead to root rots, which of course diminishes a tree's root system, which is exactly just what a tree doesn't need when a drought hits.

Scott

Your'e right Decumbent. We had THE worst flooding in 2006 that anyone can remember. Normally you literally have a hard time flooding a hole in the ground with a hose running at full pressure. Now, the ground, before it froze this winter, was so saturated that wherever you stood you left water flooded shoe impressions. Two blocks over the water backed up in the creek to the window sills! So, now I guess I have to be concerned about additional stress. Since 1988 we have experienced mostly a prolonged dry period with occaisional officially declared years of drought. It began in 1988 when we got about 8 inches of precip. instead of the normal 30 and not one drop in June, July or August. Add two successive waves of gypsy moth and you've got real trouble. I have managed to keep the gypsy moth damage to a minimum (Sevin sprays). This coming spring, because the infestation is so severe, we qualify for state area wide spraying. My particular block is the worst of the worst! Anyway, I will not repeat apply any mycorrhiza. I't didnt make any sense. Thanks for the suggestion to talk to the extension agent. Because I have been so focused on gypsy moth I wouldn't have thought of it. Now, if you think the Fraser firs would benefit from a Ph drop I will head out there with some soil sulfur.

I read somewhere that gypsy moths are slowly spreading southward, I hope not. I don't know if I would even bother trying to have oaks if I had to worry about that every year.

Is mycorrhiza the same as yourcorrhiza?

:-)

Nah, I think the latter is some kind of Mexican sausage.