Urgent! Can I save my new trees from herbicide exposure? Can I water them safely?

Asked July 30, 2020, 4:46 PM EDT

Last week our lawn service sprayed herbicide on the yard. Within a day or two, stripes of bleached-out grass appeared, but my real alarm was about the three new 10' tall silver maple trees I planted in early June. Bare-root trees from City of Plymouth and planted to their specifications. They were doing fine and growing fast for 6 weeks. But a day or two after the herbicide treatment I noticed the leaves drooping on all three trees. We'd had good rain, but less than 1 inch over the past week, so I watered them a bit, hoping that was the problem, showering water on the mulch (8 foot radius ring). That didn't perk them up and the next day they looked worse. Based on the damaged grass I suspected the herbicide treatment. The new leaves at the end of each branch (and at the top of the leader!) were withering badly. [See photo] I called the lawn service out to take a look. We decided to watch it. It's been several more days and iit's been sunny and dry for a week. I really should water these trees now. They've gotten sicker looking but I don't want to risk sending any herbicide that might still be in the mulch down to the roots through watering. Do you have any advice on watering or other treatment for these poor trees? Should I give the *extra* water to flood out any herbicide? I'd appreciate any advice you have, the sooner the better. Thanks!

Hennepin County Minnesota

1 Response

It depends on what the herbicide is. If it's one that's "foliar", it' works when it hits the leaves. I'd suspect that's what this is based on the photo but you'd need to ask the lawn company. Assuming it is foliar, then watering won't be a problem at all.

This doesn't mean that the trees will come back though. We've had LOTS of reports in the last week about damaged trees from spraying--the really hot humid weather was not even sort of ideal conditions. Do you know what day they sprayed? Lawn companies should really know that and hold off on bad days. They're trained to know when and how to apply this stuff.

I'd go with watering but I'd also stay in touch with the company. It's very possible these little guys won't make it and you might want the company to replace them for you. Knowing what day it was, and what the weather was, will help you make a case if you need them to be replaced.