Under umbrella weather

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The average adult reads at a rate of around 250 words per minute. Whether it’s life or turf, anything with a dollar involved can keep readers occupied for at least a few minutes.

The commitment over the next four minutes involves a concept using dollar in the first part of its nomenclature — and we promise this isn’t another financial or dollar spot story.

Work on a course in the Southeast within a few hours of a massive body of water? Does the course get rain? Are there low-lying areas on the property?

Consider it time for a dollarweed refresher. Even if your course doesn’t fit into the above categories, we suggest you keep reading. Perhaps your career will take you where the weed lurks.

A broadleaf weed also known as pennywort, dollarweed can interrupt uniformity and spoil aesthetics on nearly any warm-season turf species and variety covering fairways, approaches, roughs and tees. Dollarweed is a perennial. Left untreated, it will emerge next year … and the following year … and maybe the year after that.

“It’s a perennial and it has rhizomes,” says PBI-Gordon Southeast research scientist Dr. Eric Reasor. “A small patch will become a bigger and bigger and bigger patch. It’s a weed that will persist every year and get bigger and bigger every year.”

How big? Leaflets can exceed two inches. That means nasty, unsightly lies in rough-height turf. Playing golf in Florida wind is already tough enough without having to muscle the ball through dollarweed. “In rough, it can form a bit of a higher canopy,” Reasor says. “You can kind of close a ball in it or the ball will bury down in there a little bit.”

Dollarweed looks distinct: rounded leaves resemble silver dollars (hence the name) with waxy edges. Weeds are often confused with other weeds. In dollarweed’s case, the biggest mix-up occurs when a property also possesses dichondra, another perennial broadleaf weed that likes water. Two familiar shapes we all learn at young ages help determine the difference between the weeds.

“Dichondra will have one deep lobe where the stem meets, so it’s almost like a big, heart-shaped leaf,” Reasor says. “Dollarweed has a higher circle with the stem in the middle, kind of like an umbrella.”

Dollarweed is associated with umbrella weather. Courses in Gulf Coast states, especially Florida, are susceptible to dollarweed outbreaks, according to Reasor. The range extends up the Atlantic Coast to Virginia’s eastern shore. Courses in the mountains of North Carolina, South Carolina and Georgia, and northern parts of Mississippi and Alabama are less vulnerable to outbreaks.

Water accelerates and promotes dollarweed growth. In fact, it can grow submersed in water. Dollarweed will overtake parts of the course where shade inhibits Bermudagrass. It struggles handling significant traffic.

“It’s not going to tolerate cart traffic or foot traffic like a turfgrass would,” Reasor says. “High-traffic areas, if there’s dollarweed there, it’s going to get beat down and you’re going to end up with bare ground until that turf can recover.”

In Florida, spring is prime dollarweed season. Outbreak timings are pushed back a few weeks or months in other Gulf Coast states. “It likes a little bit of cool weather and that wetter season,” Reasor says. “That’s not to say it won’t persist in the heat of summer, but it just likes that cooler bit of weather, not those 90- and 100-degree temperatures.”

Reasor adds that dollarweed “can tolerate a lot of different environments,” thus limiting the scope of cultural practices to halt its spread. Basics include avoiding overirrigation, enhancing drainage in low-lying areas and managing trees to decrease shade.

Effective dollarweed control programs primarily include a curative approach using postemergence herbicides, according to Reasor.

“Any preemergence you put down, if there’s seed in the soil, you’re going to control that,” he says. “That will control weeds like crabgrass and goosegrass, but you’re not going to control those new plants coming from rhizomes with a preemergence. Nine times out of 10 you will need a postemergence herbicide application.”

Scouting should commence when air temperatures start averaging around 55 degrees. Once dollarweed is spotted, Reasor recommends curtailing it as swiftly as possible. The sight of dollarweed means it’s most likely “thriving pretty well,” he adds.

Density determines how many postemergence applications are required for control.

“It can sometimes take two applications, especially in a dense stand,” Reasor says. “It can form a real thick canopy and those leaves are real waxy, so it can be hard to get herbicides into those weeds at times. I wouldn’t say it’s a difficult-to-control weed like others, but it can definitely be a little bit tricky. Two applications provide absolute best control, but sometimes you can get it pretty good with one app.”

Herbicides possessing 2,4-D as an active ingredient are a popular and proven selection for dollarweed control. 2,4-D is one of four active ingredients in PBI-Gordon’s SpeedZone Southern EW Broadleaf Herbicide for Turf. “It has a lower amount of 2,4-D for the Florida area,” Reasor says. “It’s safe to use on all those different turf types that can be down in Florida. It’s a good mix of contact and systemic herbicides.”

The presence of a systemic herbicide in SpeedZone Southern EW allows the formulation to reach the underworld of dollarweed.

“It’s important that they get in the plant and move down and into the rhizomes, so the plant will transport that herbicide down into those underground stands,” Reasor adds. “That’s really where you get the best control, is with systemic herbicides moving down into the roots and the stands underground. If you have too much of a contact herbicide, it will just kind of burn the top leaves off and then it regrows right from those rhizomes. A good mix of contact and systemic with systemic herbicides being the most important.”

In addition to having a reliable herbicide for control, there is another significant positive regarding dollarweed: The weed doesn’t appear to be migrating.

“It’s still around those coastal areas,” Reasor says. “Is it a sandy soil thing? Is it just coastal weather? Does the ocean influence it? It doesn’t seem to be spreading quite like some of these other weeds. It might have to do with the amounts of seed it develops aren’t the same as Poa or goosegrass or even doveweed. For the most part, it seems to be just chilling where it is.”