The company is trying to avoid problems with applicators. That is a blue spruce.
You should be fine if you are spraying Trimec at the correct amount--and--if you are not spraying at close intervals. 8 to 12 weeks apart should be fine. Sandy soil carries slightly more risk.
The most sensitive trees (in my experience) are redbud, box elder, and grapvines). So true, one of my employees injured a basswood by spraying twice within 10 days.

The main problem is-- three ways usually contain dicamba--which is mobile in the soil and is taken up by the tree roots. That is why dicamba is used at a low ratio. A quarter pound per acre or something like that.

 

Better yet, apply much 3" deep under the tree out to the dripline. Do Not pile against the trunk. This will not only control weeds but also improve the soil.

 

Great visual post on arbors having proper drip line tree rings. Most of the time. This correct practice is ignored because the desire for turf outweighs proper, after installation care.
Posted via Mobile Device

 

Good posting of the proper technique of mulching around and under trees.
I don't think many will advise the use of 3-way products under such and certain surface rooted trees. There is many methods of application and each has their own faults, so to each his own.
Backpack sprayers, hand held sprayers, boom sprayers is the usual method of homeowner's for my area. I usually see damage because of improper calibration and overdosing a gallon of water with product.

 

Better yet, apply much 3" deep under the tree out to the dripline. Do Not pile against the trunk. This will not only control weeds but also improve the soil.

Also keeps inattentive employees from stripping the bark off the tree and killing it. Big fan of mulch rings, they add visual interest to an otherwise plain scape.
Posted via Mobile Device

 

Thank you for your reply's. I don't want to much them because I the the trees trimmed up far enough that I am able to grow grass under them but if grass can grow so can the weeds. I have seen tru green and other company's spraying right next to trees and shrubs and just wanted to make sure I was not going to hurt mine. Im going to use a tow sprayer on my mower and I have calibrated.

 

Grass growing under trees can work with enough sunlight. The problem is competition for nutrients, water & just plain competition.

Also the fact that the potential for damage to arbor based on turf label products
is a high risk factor. It's like roulette. Arbor damage may occur just be ready to bite the bullet.

 

Thank you for your reply's. I don't want to much them because I the the trees trimmed up far enough that I am able to grow grass under them but if grass can grow so can the weeds. I have seen tru green and other company's spraying right next to trees and shrubs and just wanted to make sure I was not going to hurt mine. Im going to use a tow sprayer on my mower and I have calibrated.

TG doesn't care they will either be fired by the time the tree dies or they will blame the lawn guy.
Posted via Mobile Device

 

No grass under the trees also means no crashing of mowers into the bark or else tearing of the bark with string trimmers. I also rather not have grass around trees because that normally means having to raise the height of cut vs the rest of the lawn so the grass even survives. Lots of lawn people end up with no grass under trees by default because they are cutting at the same height or even shorter under a tree.