If you manage bentgrass putting greens, weed control is probably creeping its way onto your radar right about now. It’s a good time to prevent weeds before they become a visible problem. In addition to cultural practices, what pre-emergent herbicide options are there?

We have two products that provide pre-emergent weed control on bentgrass putting greens. 

The first is Bensumec 4LF, a liquid herbicide containing bensulide. Bensumec controls annual grasses, including crabgrass, Poa annua, and goosegrass. It is most effective under low or normal weed pressure. Bensumec typically requires two applications, with the first being in late March or early April. Make the second application between six and eight weeks later. The recommended rate is six ounces per thousand square feet. It’s important to thoroughly water in the product as soon as possible following the application. 

If you’re struggling with Poa annua on your greens, you can make a third Bensumec application in late August or early September. Keep in mind that the maximum yearly rate for this product is 18 ounces per thousand square feet.

If you’re concerned about goosegrass on your greens, consider a product called Goosegrass/Crabgrass Control. It contains bensulide and oxadiazon to control goosegrass and crabgrass as they sprout. Goosegrass/Crabgrass Control is a granular product best spread in two applications at the half-rate. The first application is typically around mid-April, depending on temperature and rainfall. To prevent speckling, only apply to dry turf. Don’t apply to thin or stressed turf, and water in the granular thoroughly and promptly after application. 

The second application should be two weeks after the first, again at the half-rate of 1.31 pounds per thousand square feet. Ideally, apply before the soil reaches 55°F at a four-inch depth, and don’t apply within seven days after aeration.

Read the label of whichever product you choose before applying it, and contact your sales representative with any questions about pre-emergents this spring.