Do you fight the same broadleaf weeds every year? Is summer weed growth getting you down? If so, you might have chronic broadleaf weed disorder. As summer kicks into high gear, you will need herbicides to tackle these unwelcome annual guests on your golf course. In most states, you will have access to high-quality herbicides that can control many broadleaf and grassy weeds. But before we get into specifics on herbicide selection, let’s look at some strategies for optimizing your applications:
- A thriving weed will absorb and translocate herbicides better than one that is struggling. It may seem counterintuitive, but encouraging weed growth with ample moisture and food before an herbicide application will result in better control.
- Don’t mow the weeds for a few days before applying an herbicide.
- Irrigate before you apply the herbicide, not after.
- In warm weather, be careful with ester formulations of herbicides as they will volatilize more rapidly than amine formulations. You can end up getting less active ingredient into your target with an ester formulation.
- Depending on the maturity of the weeds, you may need a second herbicide application to get full control.
- Make sure you have healthy turf to help fill in voids left by dying weeds.
The following is a small sample of herbicides and the weeds they help control that are common on golf courses in the western United States. Three- and four-way herbicides do a great job controlling many of the common summer weeds. These multi-ingredient herbicides usually include combinations of 2,4-D, dicamba, MCPP, MCPA, carfentrazone, sulfentrazone, and quinclorac. Dandelions, false dandelions, some types of English daisies, and plantains are just a few of the weeds these active ingredients control.
Other herbicides that have good efficacy on summer weeds are triclopyr for clover and yarrow, clopyralid on thistles and black medic, fluroxypyr for clover and black medic, and penoxsulam on certain types of English daisy.
While herbicide applications will be effective in reducing your current weed population, you’ll get far better control when you treat weeds in the fall or spring months. Make notes of areas with high weed pressure this summer as you treat, then re-treat in the fall and the following spring and next year’s crop should be smaller.
West Region Agronomists:
Brian Whitlark, regional director – bwhitlark@usga.org
Cory Isom, senior consulting agronomist – cisom@usga.org