Questions regarding naturalized areas or reduced input areas don’t only cover how to increase aesthetic quality or increase playability but how to accomplish these things with the fewest inputs as possible. This means thinking about the relative cost of inputs, the time it takes to provide an input, and which inputs are worth that time and money. In the end, the goal is to provide the beauty of contrasting tan colors and inflorescence in the summer with few inputs. However, success will be accomplished by developing a plan to include the most necessary inputs.
1Which inputs are most important in naturalized areas?
Because these areas aren’t mowed regularly, weeds can get out of hand quickly. Herbicide applications are the most important input to maintain pure stands of whatever was established. When perennial weeds with vast networks of vegetative reproductive parts, like common milkweed and Canada thistle, are left untreated they get stronger and multiply quickly. Turf managers should make time to treat these areas at least once per year; it won’t make a huge difference whether it is in the spring when weeds wake up or in the fall as they prepare for winter – consistency is key because weed pressure is constant.
2Which herbicides will be most valuable in naturalized areas?
Millennium Ultra® 2 is a broad-spectrum herbicide that consistently provides great broadleaf weed control on golf courses, including in naturalized areas. Some weeds emerge late and some areas have high weed pressure and require some spot treatments mid-season. Sure Power® will burn-down these weeds quickly and provides activity on a range of mid-season weeds including broadleaves, annual grasses, and many sedges. Those who have established these areas with fine fescues have a huge advantage when it comes to control of perennial grasses – sethoxydim and fluazifop can be applied over the top of fine fescue species to provide selective control of many perennial grassy weeds like quackgrass, reed canarygrass, etc.
3How are naturalized areas established around in-play areas?
At establishment, seeding grasses at a low rate is key. A playable naturalized area may have 1 large plant per 1 square foot of area. This is a huge difference from the hundreds or thousands of grass plants in the same area mowed from 0.125 – 4 inches, and may call for a vast departure from what we are used to. Accomplishing such a sparse stand of plants is easier said than done, but here are some tips:
- Choose plant species that are clump-forming and won’t spread via stolons, rhizomes, or other vegetative structures into open voids. If you are seeding fine fescue species, this may include hard and sheep fescues versus creeping red fescues.
- Decrease your seeding rate. For fine fescues, 10 lbs of seed per acre, or even less, may be sufficient. Set up a few test plots and compare a few low rates so you become comfortable with rates much lower than commonly used.
- Add some annual ryegrass to the mix to provide some quick cover and competition for your desired species – this is a good way to ensure a thinner stand.
4How can established naturalized areas be thinned to increase playability?
Once these areas are established, they become much more difficult to thin out, so starting thin is key. These options for stand thinning should be tested as research in small areas as they are few and inconclusive. Keeping these areas thin will help increase plant aesthetics because they aren’t competing as much with each other, but thin stands increase the likelihood of weed infiltration, so, again, weed control is key.
- Use PGRs. There is anecdotal evidence of superintendents using PGRs such as trinexapac-ethyl and prohexadione-Ca (Anuew™) to thin stands, but little conclusive research. PGRs are used in grass seed production fields to reduce lodging (plants falling over) and increase seed production, but not necessarily to thin turf stands.
- Use preemergence herbicides. Because naturalized areas produce seed each and every year, a huge amount of seed is being added to the soil seed bank. If these seeds are allowed to germinate and recruit, they may increase density over time. A preemergence herbicide application may limit survival.
- Nonselective herbicides like glyphosate or glufosinate (Cheetah® Pro) could possibly be used in creative ways to thin out naturalized areas. Perhaps a boom sprayer could be used with every other nozzle turned off and a random pattern through the areas. This may seem like an odd method, but it would get the job done quickly.