Recommended treatments for stressed Pin Oak?

[jmanikowski]

I have a ~70 foot tall mature Pin Oak in my front yard that is moderately to significantly stressed and chlorotic and I'm trying to cost-effectively save this tree. Aside from proper pruning and nutrient and pH recommendations from a soil sample analysis, would anyone recommend a Cambistat/Paclobutrazol treatment?

Also, a local arborist said he might recommend an iron injection, pending the results of the soil analysis, though when I received the analysis, there was no indication of iron levels. How would I know if I need an iron injection?

Lastly, I'm currently awaiting the results of a petiole analysis to determine if this tree is diseased in any way. Are there any other analyses that one might suggest paying for to help determine the health of the tree?

Thanks in advance for your replies.

 

[ATH]

*A foliar test is often as valuable as soil test, but it costs a little more (but less than un-needed treatments). (A little late for that this year though...)

*Besides the soil test, how is the soil? Is the tree mulched? Is the soil compacted around it? Does it get adequate water? It is truly amazing what radial trenchning with an Air Spade or Air Knife can do. I have seen trees that fit your description. After radial trenching, they look great and resume normal growth - no soil additions, no injections.

*I have never used Cambistat, but have heard others be happy with the results.

 

[jmanikowski]

@ ATH

I'm unfamiliar with a foliar test...is this something that should be done in the spring, and if so, do you have the name of a testing facility/company that you could refer to me?

In my opinion the soil is not very good. I just moved into this house about 3-4 months ago, so I haven't had time to do everything that could promote its health. The area is mulched now, though I don't think it had been for at least 4 years. Aside from lack of nutrients and being slightly too acidic, the soil is compacted in the entire front yard and it appears that some excavation was done about 3 years ago to put in a new well and water line.

If you think radial trenching might be the most beneficial thing for this tree, I was wondering if you could provide more info on that?
1. When is the best time of year to do this?
2. Do you think an air spade can be rented at a local tool rental center?
3. Any other instructions would also be helpful.

Thanks.

 

[ATH]

I use Spectrum Anayltic for testing. There are many other labs out there offering similar services. Penn State does it too.

*Make sure the mulch is not too deep (no more than 2-3" and not piled against the trunk of the tree)
*Normally, chlorotic (yellowing leaves) pin oak is because the pH is too high...but how low is yours?
*Construction-induced compaction certainly causes may problems. If the trenching cut roots, that will cause further problems.

Regarding radial trenching:
1) Any time there is moisture in the soil is a good time for Air Knife work.
2) It is unlikely, but not out of the question that a rental yard would have one. The bigger expense is the compressor. There are rumors about home-made tools, but none work well as the ones that have a tip designed for the best air flow. For a one time job, you'd be better off hiring it (if there is anybody in your area that does it) rather than investing in making a "might work" tool and spending $125+ for compressor rental.
3) This is not rocket science (but if it were, you could probably hire a rocket scientist cheap after the launch the last shuttle in Feb...). If the problem is compacted soil, you are trying to aleviate that situation. While you could do the same work over the entire rooting area, research has shown that the radial trenching provides drastic improvements for rooting conditions (with much less labor than area-wide decompaction). The trenches should be 8-12" wide and 16-20" deep. I also put holes between the "spokes" similar to vertical mulching. You can back fill the trenches and holes with something less subject to compaction (such as a mix of soil/organic material/perlite(or diatomacious earth) and fertilizer if needed based on soil test).

Another option would be vertical mulching. This is a more realistic do-it-yourself treatment. Buy the 2" auger bit and rent a gas drill. Drill holes on a 2'x2' grid and back fill with mix described above.

 

[jmanikowski]

pH is 4.8