Weeding out trouble

For many golf course superintendents, fall is a time of transition. There is still plenty of play, but it’s also a time to be thinking about the winter ahead and seasons yet to come. There are still turf issues to contend with, however, among them controlling weeds and neutralizing or eliminating pests.

Some situations are regional in scope. A superintendent in New York will likely find himself facing different circumstances than a colleague in the Southwest or California.

In light of that circumstance, the USGA Green Section has divided the country into four geographic regions.

East

The East encompasses 13 New England and Mid-Atlantic states. Adam Moeller works with the USGA Green Section and encounters a variety of weed issues in the region. “Probably our biggest challenges are kyllinga and yellow nutsedge,” he says.

Some of these issues are the result of long-term heat and humidity issues. But others are brought about by contamination that can occur during aeration or overseeding. Bentgrass seed spreading into the rough during the aeration process, for instance, becomes a contaminant.

Dr. Jason Fausey is a research scientist for Nufarm Americas. He notes that in the Eastern part of the country annual and perennial species of kyllinga are becoming more prevalent in the region and showing no signs of going away anytime soon. “Both have infested that area and are continuing to spread to more and more courses,” he says.

South

The South Region covers nine states, most of them along the Atlantic and Gulf Coasts. Because of the climate, superintendents in parts of this region face some unique challenges. What would be a standard herbicide protocol in Iowa for instance might not last the season in parts of Florida.

In this region, goosegrass is a persistent issue. It germinates in late spring and early summer, then begins to appear in July and August.

“Controlling goosegrass has become more of a challenge in recent years because of documented cases of herbicide resistance,” Fausey says. “With the already limited number of tools, there is a lot of concern about long-term, goosegrass management. It’s a topic many superintendents are discussing. They’d like to develop a sound weed-control program before they encounter a major problem.”

Spurge, another broadleaf weed, has a growing pattern similar to goosegrass. It will tend to germinate fairly early in the year and then kind of sit there as a small plant until the soil temperatures get very warm.

West

In the West region, which encompasses 13 states in the Rocky Mountains and along the Pacific Coast, along with Alaska and Hawaii, annual bluegrassrass/Poa annua is a frequent topic of conversation. The problem is particularly acute in Northern California, where annual bluegrass is more likely to thrive.

Patrick Gross a regional director for the USGA Greens Section, works out of Santa Ana, Calif., in Orange County. When he visits the northern part of the state, he encounters Poa annua on a regular basis.

“Poa annua is a big component of a lot of fairways and rough,” he says. “In a lot of locations, they’re not doing anything to necessarily control it. Some are, but a lot of them aren’t.”

Central

The Central Region includes 13 states. Conditions there are similar to those in the Northeast and Mid-Atlantic. Turf issues in this part of the country include annual bluegrass, which usually begins to germinate in early fall.

Crabgrass is also an issue in this part of the country, along with broadleaf weeds such as dandelions and clover. The latter usually makes its appearance in August, but the autumn of 2015 is the time to take steps to address the issue for 2016.

Zac Reicher, technical specialist on the Bayer Green Solutions Team who concentrates his attention on cool-season grasses, points out that newly seeded turf is particularly vulnerable to infestations of Poa.

“[Seeding] should be done as early in August as possible,” he says. “Seeding early will dramatically limit your weed problems. Conversely, seeding after Labor Day or even later dramatically increases the problems with annual bluegrass.”

Reicher says that the right formula for dealing with annual bluegrass varies according to the maturity of the turf. Reicher says it’s vital to get a head start on potential problems. “It's important to start or continue using these products to limit annual bluegrass well before it really gains a foothold over the desired turfs,” he says.

Wading through weeds

Reicher’s colleague Laurence Mudge specializes in warm-season grasses and the challenges that go with them. “Warm-season turf tends to have a longer growing season” he says, “and thus a longer period of weed invasion … We also have winter weeds that invade during the fall/winter months on warm-season turf.  Weed control on warm-season turf is a 12-month-a-year process.”

Warm-weather weeds include doveweed, Virginia buttonweed, tropical signalgrass and dallisgrass, along with the traditional crabgrass, goosegrass, Poa annua, sedges and kyllingas, and various broadleaf weeds.

Mudge finds pre-emergent products to be the most beneficial from a bottom-line standpoint. “Pre-emergent control of weeds is normally the most cost-effective approach rather than relying on post-emergent products,” he says.

Superintendents, whether they are in Miami, Fla., or Miami, Okla., must be aware of the latest environmental regulations. Mudge notes that the popular herbicide monosodium methanearsonate, (MSMA) has been banned in Florida.

In 2012, the University of Georgia Extension Service evaluated an assortment of products for their effectiveness in controlling annual bluegrass in residential turfgrass. Three of eight pre-emergent herbicides were rated excellent: atrazine, benefin and simazine. From a group of eight post-emergent, five received an excellent rating: atrazine, foramsulfuron, glufosinate, glyphosate, and simazine.

Weed-control programs are not implemented in a vacuum. Fausey emphasizes that the most effective weed-control programs are elements of a comprehensive agronomic program.

Maximizing the health of the turfgrass on each course and then focusing on herbicide use is the key, he says. “Cultural practices such as watering, fertilizing and mowing all greatly impact the level of weed pressure and will determine the success of a herbicide application,” Fausey says.

“In each area of the country, superintendents can develop the best herbicide program possible with the ideal product selection, application rate, application timing, application method and still not be successful if they don't blend this program into their overall management program,” he adds. “Specifics such as a pre-emergence herbicide applications versus when aerification occurs or topdressing versus a post-emergence herbicide application. To have success, every action on the course needs to flow together.”

The importance of getting a jump on potential problems can’t be overemphasized. Fausey notes that the fall is a critical time for superintendents. He says it’s important that superintendents avoid the temptation to “back off the throttle.”

“This is the time of year when turf has been under a high amount of stress for a fairly significant period of time,” he says. “This is the time of year that can pay dividends going into next year. You would like to have healthy turf going into wintertime and often that isn’t the case, especially courses that may shut down or may have had a tough year. Fall is a great time to rejuvenate your turf.”
       
PEST POTENTIAL

In addition to weed issues, superintendents must be wary of pests, both in the air and in the soil.

In some parts of North America, European crane flies can cause significant turf damage. They thrive in areas where summers are cool and winters are mild. They are found chiefly in New York, parts of Canada and the Pacific Northwest, although they have been found elsewhere.

There are two species, but only one can fly, which makes it a greater threat. The adults lay their eggs in August and September, and the larvae can inflict significant damage.

Dr. Gwen Stahnke of Washington State University says it’s important for superintendents to be proactive. “It is a timing issue with the application of products,” she says.

The least toxic formulations such as imidacloprid and thiamethoxam have to be applied in early September when the crane flies are laying their eggs to get the best control. If you wait until November, the control of larvae drops significantly with these products. The most effective synthetic pyrethroid product is bifenthrin. This is effective almost at any time frame during the larval stages, except during pupation and adult stages.

Grubs are also an issue in the autumn. “At this time of year, grubs are large enough that they will cause more damage,” Syngenta western technical manager Dean Mosdell says.

Grubs feed on organic material, including plant roots and they are a food source for vertebrates.
Those vertebrates includes raccoons, skunks, moles, and in some areas, armadillos. Their presence often indicates a grub infestation.

The grub larvae will hatch in the summer and stay active through the fall until cold weather drives them underground. They will complete their life cycle in the spring.

Mosdell points out what superintendents know all too well – a skunk or raccoon can create a lot of havoc on a golf course. “A healthy turf can tolerate five to 10 grubs per square foot,” he says, “but that skunk may be after just one to two grubs and will dig a square-yard hole looking for them.”

Keeping grubs away requires a season-long effort. “Prevention is always better than a curative application,” Mosdell says. “There are a lot of good insecticides for grub control that should be applied from May through July. But once you get past July, the grubs are big enough to where these preventative materials aren’t as effective. There are a few products for curative control that are okay. The level of control is not 100 percent. The application to control the grub is less effective and the materials are limited as to how effective they are as a curative application as you get into September and October.”

Superintendents are advised to check with their state game commission and be aware of any regulations concerning the removal of animal pests.

Rick Woelfel is a Willow Grove, Pa.-based golf writer and frequent GCI contributor.