Since 2014, Neil Radatz at Hawks Landing in Madison has been kind enough to let us play around with weed control strategies in native or non-mowed rough areas. We have received funding from the Wisconsin Golf Course Superintendents Association and the United States Golf Association for this work.
We have three studies at Hawks, one looking at the implications of mowing and returning vs. mowing and removing vs. not mowing. Another study is evaluating various herbicide effectiveness, and the third is looking at using low rates of glyphosate to thin out really thick stands of grass and weeds. One of the challenges of having native areas is that if they are in play, golfers can spend a lot of time searching for balls. Ideally, balls would be easy to find and not too difficult to play out of. But many of the the areas can get overgrown and are difficult to walk through let alone play out of. We’ve found some good success with low rates of glyphosate (1 to 2 lbs AI per acre) applied in May. I am always nervous about recommending applying glyphosate to actively growing, desirable grass, but the last two years of data are suggesting that it may be an inexpensive tool to thin out native areas and keep play moving along. However, note that your soils and grass species/cultivars may vary in tolerance to glyphosate. Try it out on a small section first!
The full report can be downloaded here (Weed control in native areas report 2016), but if you don’t have time to read it all, the Table below shows the efficacy of glyphosate applied to these thick areas in May where we found significantly greater levels of bare soil, resulting in better playability ratings. Also, the percentage of weeds in these plots were among the lowest of all treatments.