tree seeds

Asked March 16, 2013, 10:15 PM EDT

Hello, My neighbor's tree has expelled thousands of long seedlings (like elongated tear drops - about an 1.5 inches x 1/4 inch at its widest point) that get into my flower beds and grass. See picture attached. They germinate and I spend hours plucking them. Is there some sort of herbicide I can apply on them to stop them from germinating or kill the germinating seedlings but not killing grass or other plants? What do you recommend? Also if there is an herbicide, when should I apply it? Do I want to avoid doing it before a rain or snow?

Jefferson County Colorado

1 Response

Your neighbor has a female ash tree that bears these seeds. They germinate readily if they fall onto bare soil or thin lawn grass. KY bluegrass tends to thin out when it is excessively shaded.

In a lawn area, the best approach may be to try to thicken the lawn density (to exclude ash seedlings) by core aerating, overseeding (with a slightly more shade-tolerant variety of KY bluegrass) and adequate fertilizer.
If that's not an option, one of the preemergent ("crabgrass preventer") herbicides used on the lawn could help prevent the ash seedlings.
If the ash seeds are germinating in the FALL, the use of a preemergence herbicide (i.e., "crabgrass preventer") in late summer/early fall would probably provide some control. One preemergent product, isoxaben (sold as "Portrait Herbicide" in the homeowner market and on the internet as Gallery). If the tree seeds are germinating in the SPRING, then an application of isoxaben between March 1-25 might be effective.In the end, regular lawn mowing will kill the young ash seedlings in your lawn. Disclaimers: a. Isoxaben has NOT been tested for the control/prevention of ash seedlings. b. Isoxaben would prevent seed germination of flowers in your flower beds c. Read and follow product label instructions carefully