How to get a tree to bounce back after accidental herbicide treatment?


New Member
A customer has two hickories that dropped their leaves a month early last year. The local forester suspects the lawn care folks treated the weeds around them with roundup. The trees look relatively healthy, but the customer is very concerned and wants to make sure they're saved - he suggested applying some fert. I haven't done any soil sampling and understand that not all ferts are the same and certainly no cure-all. Any suggestions?


Well-Known Member
No no fert, es muy malo...

Glyphosate shouldn't be a big problem unless a lot got on the trunk or perhaps surface roots.

Pics of foliar symptoms and the turf area may help but lawncare application records would be far more appropriate to look for potential misapplication.

I would also consider some of the foliar diseases of hickory that can cause some early defoliation as well as perhaps dry soil conditions amongst other possible problems.


New Member
Thanks JD. Yeah, I'd been thinking suggesting heavy watering to dilute any residuals. Foliar diseases of have a file on that? I'll break out my Sinclair and also do some googling.


Well-Known Member
JD is right, it’ll take a lot of glysophate to defoliate and entire tree unless it was misted over the leaves or concentrate on roots and/or bark. And even then you will get deformed leaves not defoliation. Hickory is well known for loosing leaves early in our area and normally bounce back without any assistance. Be careful with heavy watering, especially if you are chasing something that isn’t something (if you know what I mean). You could cause other problems that you certainly don’t want to be dealing with like root decay. Do soil tests, follow up with landscape contractor records (good luck) and certainly look at Sinclair. Look at the facts you can get your hands on, the prescribe the proper response. Oh and keep us posted on your findings.


Well-Known Member
Watering will do nothing now. Any glyphosate activity will have already happened...there is nothing left to flush out from last fall if that was the problem.

Does the homeowner agree that the weeds were treated with glyphosate? Were all the weeds dead last fall?

If you need to deal with bad stuff in the soil, I'd look into biochar and maybe some of the biological/micororganism enhancements before long fertilizers. But until they come out or don't come out this spring, I wouldn't feel comfortable making a recommendation either way. Are hickories in full leaf down there? How do these look this spring?


Well-Known Member
I've treated air potato with 2% glyphosate in the past. Since it elevates, we sprayed the ttees that it was on. We would get leaf scorch on those trees, but would not kill them. They would refoliate. The scorch was from the adjuvant as much or more than it was from the glyphosate. Check the label - glyphosate, as a common homeowner herbicide, should not be soil active. You would need a vector to get it into those trees - a bark penetrant like Impel, or a foliar spray cocktail that volatilized on a hot, still day. The odds are heavily against either of those circumstances occurring in L & O application. I would look for non-glyphosate causes, or a perfect storm of several minor causes.
  • Like
Reactions: ATH

Tom Dunlap

Here from the beginning
For insights about what a deadly herbicide attack looks like and how it was remediated look up 'Treaty Oak Austin'

Ross Perot signed a blank check ...really! cover the costs


Active Member
If soil got inundated with Glyphosate or other chemical, after washing/leaching away can treat ground with Seasol (Seaweed fertiliser) - this helps put microbes back into soil and assist getting soil back into a 'working' condition, where food is made available for roots to uptake and the skin of roots can get back their biosphere to absorb... still takes a while to work but I believe is an application that sensitively does more than a lot of other intervention methods...


Well-Known Member
Maybe it wasn't glysophate. I had a client about a year ago at this time with the same issues and blaming the same folks. Turned out their lawn guy was using Mojave in all the landscape bed areas to keep weeds down. Slowly killed a bunch of landscape plants and 11 oak and sweetgum trees. Soil samples tested positive for the AI in Mojave and the guy kept a package of the material on site. Soil test was $115 and took forever for results to be returned. It might be worth it for your clients though.