non-toxic pre-emergent ?

Asked February 22, 2020, 5:26 PM EST

After years of neglect, our town house association is trying to update the landscaping. A landscape company has developed a plan for our consideration. One step in the plan calls for using a pre-emergent to control future weeds. The suggested product is Treflan. While Treflan claims to be less dangerous for the Environment than Bayer-Monsanto's Roundup, we hope your experts can direct us to the best, least toxic product or procedure to accomplish our goal?

Hennepin County Minnesota

1 Response

Thank you for writing.
In order to answer your question, I need to understand it better.
Pre-emergent herbicides kills new weeds as they are germinating. They do not affect established weeds.
Post-Emergent herbicides are the opposite; they kill established weeds but do not effect weed seeds that have not germinated or started to sprout.
Selective herbicides affect weeds sharing a particular biochemistry.
Non selective herbicides essentially kill all plants.
https://web.extension.illinois.edu/hortihints/0406d.html

Glyphosate [Round up] is a non-selective, post emergent herbicide. https://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/pests-and-problems/pesticides/glyphosate.aspx

Treflan (Preen)is a selective pre-emergent herbicide. It is highly toxic to fish and other water organisms and should not be applied on land that slopes to or drains to wetlands, streams, or storm sewers. https://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/pests-and-problems/pesticides/treflan.aspx

So here is my question back to you. Round Up and Treflan are not comparable. What are you trying to do with the herbicides? For example, if the townhouse property has a lot of buckthorn, it is easy to remove by hand as soon as the leaves appear. If you are trying to control dandelions or creeping charley, best practices are to let them blossom as the first feast for bees. https://turf.umn.edu/news/creeping-charlie-management-and-value-pollinators You can non-toxically control these plants with a sheet of black plastic over the ground to bake everything. This is called solarization. In short, write some more please.