Saturday, February 23, 2008

Turfgrass - Spring Seedings

The following is an article on weed control in new spring turfgrass seedings.

Crabgrass and other summer annual weeds are the major limiting factor when establishing cool-season turfgrass in spring. In most areas of the transition zone and north, grasses like fescue, Kentucky bluegrass, and perennial ryegrass can be seeded and established in spring granted you start early and can avoid summer annual weed problems.

Three herbicides are currently registered for crabgrass control during establishment of cool-season grasses. These herbicides include siduron (Tupersan), quinclorac (Drive), and mesotrione (Tenacity). All of these chemicals can be applied at seeding of tall fescue, Kentucky bluegrass, and perennial ryegrass with the exception that quinclorac must be applied seven days before Kentucky bluegrass seeding. Mesotrione is safe on tall fescue but can injure fine fescues (such as creeping red fescue) and low rates should be used on ryegrass establishment. Siduron controls crabgrass, foxtails and some other summer annual grasses but does not control broadleaf weeds or sedges. Quinclorac controls crabgrass, foxtails, and some other summer annual grasses and suppresses many broadleaf and sedge weeds. Mesotrione controls crabgrass and foxtails and will suppress other grasses. It also has activity on may broadleaf weeds and sedges.

In most cases, siduron will need a follow-up treatment with an herbicide that controls broadleaf weeds later in the season. Quinclorac is best applied at planting and approximately five weeks after planting. Mesotrione can be applied at planting and then again at 4 weeks after planting. These three herbicides can make the difference between a stand of turfgrass and a stand of crabgrass when seeding in the spring. Always read and follow instructions on the label before using any pesticide.

Modified with the addition of information on mesotrione from the Frequently Asked Questions section of Turf Weeds from Virginia Tech

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