I try to impress on people that when they are trying to control weeds in their lawn that the largest weed is the trees. The same chemicals that control dandelions, crabgrass and dallisgrass can also kill your trees.
Red oaks are particularly sensitive to herbicides, especially Metsulfuron. I have seen numerous trees this spring that have been affected by this chemical in lawns that are treated by professional lawn care companies. These companies do an excellent job of creating weed free, green lawns. However, in the process they are poisoning the trees and other life in the landscape. Here is a picture of a young red oak affected by Metsulfuron:
This lawn was treated this spring with Metsulfuron. The older leaves are deformed and leathery and the new leaves are emerging with a very yellow color. Symptoms vary and if the chemical is applied before the tree’s bud break, the tips of the limbs won’t emerge until late in the spring or early summer, or sometimes never.
Metsulfuron is an excellent herbicide, but it should never be used around trees. If you have a professional lawn maintenance company treating your lawn, ask them what chemicals are being used. Ask them to show you the label for the chemicals and read the precautions on the labels. Metsulfuron (and many others) will state on the label that it should not be applied in the root zone of trees.
Weed and Feed fertilizers often use Metsulfuron as the weed control chemical. They also use Atrazine which is another very toxic herbicide. Weed and Feed should never be applied to a lawn that has trees growing in it. The label on Weed & Feed will state that it should not be applied in the root zone of trees. Consider your whole yard the root zone of your trees.