It is important to have at least four weeks between glyphosate treatment and grass seeding - this allows the grasses killed by glyphosate to decay and not interfere with emergence of the seedling grasses.
Tall Fescue Removal Option 2
The other option is to selectively remove tall fescue with herbicides when the tall fescue infestation is less than 50 percent. Research at UK has shown good control from Plateau applied at 10 or 12 ounces per acre. Plateau must be applied with methylated seed oil or a non-ionic surfactant; consult the Plateau label for specifics. Tall fescue was controlled at these rates when applied from May through October.
Two consecutive annual applications did not harm Kentucky bluegrass. Weekly mowing of the pasture did not reduce tall fescue control from Plateau applications.
Cimarron at one ounce per acre will also remove tall fescue; however, the amount of tall fescue removal from Cimarron is less than that obtained with Plateau.
Care should be exercised when applying Plateau to orchardgrass. Under good growing conditions (warm, moist soil, warm air temperature) our research has revealed excellent tall fescue control without injury to the orchardgrass. However, under abnormally cool, dry conditions in early spring experienced near Lexington in 2005, orchardgrass injury was noted in some fields from treatment of Plateau.
Plateau and Cimarron persistence in soil issues
Follow the label directions for seeding pastures after Plateau or Cimarron applications. Under very dry conditions such as the summer of 2005, Plateau can persist in the soil and prevent germination and emergence of Kentucky bluegrass and orchardgrass. Consult the Plateau label for specific instructions.
Nimblewill in your pastures
Plateau and Cimarron may reduce tall fescue in pastures but will have no effect on nimblewill. Usually, when tall fescue is killed, especially in large patches, nimblewill and other weedy grasses will replace the tall fescue. This occurs because the removal of the fescue provides bare ground which provides an excellent site for nimblewill germination and growth.
Pastures containing large amounts of nimblewill and tall fescue should be renovated using Option 1 described above since glyphosate will kill the nimblewill in addition to the tall fescue. Establishment of a good cool season grass mixture in the fall severely limits nimblewill germination in the spring.
Now is the time to treat the lawn for crabgrass
As we look around, it seems spring has sprung. Of course, this is Kentucky and a few more cool or even cold days are still ahead of us.
Even though we know there may be a few cool days ahead, we need to start thinking about crabgrass control in the lawn. April 1 is the recommended time to treat for crabgrass with a pre-emergent herbicide. The warm days we have had the last couple of weeks, makes it even more important to get the herbicide on early.
There are several products on the market and most will do a satisfactory job. There is only one, however, that can be applied at the time you are seeding desirable grasses in the lawn, that is Siduron.
Many pre-emergent herbicides are sold on fertilizers, many are not. Whether you buy one with fertilizer is determined by what you did this past fall.
If you fertilized your lawn in October or November, you should look for pre-emergents that are not incorporated on fertilizers. If you did not fertilize this past fall, a small amount of nitrogen fertilizer should not be a problem this spring.
UK does not encourage spring nitrogen applications for a variety of reasons.
Those reasons include increased mowing frequency, and the development of surface roots which are more susceptible to drying out in hot dry summers.
For more information on lawns or pasture, contact the Jessamine County Extension Office at 885-4811.