Best times to apply herbicides.
When is the best time to apply herbicides to control weedy plants in my lawn?
To control sand burs at this time of year, you can apply Imazaquin while your Bermuda is still green. Or you can wait till the Bermuda is dormant and apply glyphosate. Glyphosate will also kill the other weedy grasses in your lawn. However, you will still have to apply a pre-emergent in the spring to control the germinating seeds of crabgrass and sand burs.
The most important step in controlling broadleaf weeds is to properly identify the weeds. Broadleaf weeds have a wide leaf with net-like veins whereas weedy grasses have a narrow leaf with parallel veins. October through November is the best time to control winter broadleaf weeds while the plants are small and lower rates can be used. The next best time is during late winter to early spring, but higher rates will be needed.
The most common post-emergent herbicides are 2,4-D, MCPP (mecoprop), and DPC (Dichloprop). These are relatively immobile in the soil which means that nearby trees and shrubs won't be threatened by root absorption. If Banvel (dicamba) is added to the herbicide to control tough weeds, then you never want to apply the herbicide within the dripline of trees and ornamentals. If you wait till your Bermuda is dormant, glyphosate can be applied to the lawn and will kill anything that is green.
For more information contact the OSU Extension Center, 14001 Acme Road, corner of MacArthur and Acme Road in Shawnee or 273-7683.