John from Ft Worth Tx writes
Consult with your local Cooperative Extension Service for more specific applications timings for your local area to apply Specticle 20 WSP Pre-Emergent Herbicide. Their contact information can be found by clicking the link below.
http://www.ahs.org/gardening-resources/master-gardeners
http://www.csrees.usda.gov/index.html
Answer last updated on: 12/13/2013