Some Herbicides Are Killing Trees

Beware of weed killers containing MSM!

If you are routinely spraying herbicides to kill weeds around trees and shrubs, beware.  Many products containing the weed-killer glyphosate also contain a chemical called metsulfuron-methyl:

“Over the past few years, there have been numerous inquiries regarding damage to ornamental plants growing near turfgrass areas that have been treated with metsulfuron-methyl-containing herbicides. Most of the inquiries are in regard to stem die-back, brown “fried” or “scorched” foliage, delayed leaf appearance, and patches of necrosis (dead tissues) in the phloem (plant’s vascular tissues). Injury symptoms are typically reported two to four weeks following applications made during hot and dry weather (although not exclusively).” 

Tree damage is becoming more prevalent.

Originally patented by Dupont, the patent has since expired, making this product more accessible and affordable.  Because of this, it is being used much more often, which is why we are seeing more MSM damage with trees and shrubs in the landscape.

Systemic delivery causes injury.

MSM (Metsulfuron-methyl) is a systemic herbicide, which means that it is translocated throughout the plant tissues.  Its mode of action inhibits the production of three essential amino acids that certain plants need to survive.  Because this chemical is systemic, it can also penetrate the roots of trees and shrubs.  Remember that tree roots often extend 2-3 times the diameter of the drip zone, and are frequently only 2 inches below the soil, and in many cases on the surface.  

Identify the Root Zones.

Any roots or root suckers that get sprayed, can translocate the chemical throughout the tree.  If you have trees or shrubs planted in turf areas where you are spraying herbicides to control turf weeds, you may be unwittingly poisoning your trees.

If you are growing trees in turf areas, be sure Not to use products containing MSM.  It is used in many products and formulations, so BE SURE TO READ THE LABEL thoroughly.  Metsulfuron-Methyl is dangerous to trees and should be avoided near them to ensure that our precious and valuable trees survive.


donna corbelli castro
Posted: August 16, 2023

Category: Florida-Friendly Landscaping, Home Landscapes, Horticulture, UF/IFAS, UF/IFAS Extension, , Work & Life

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