Phasing it out

The battle against nematodes might have swung in the favor of the nematodes. Nemacur, a product produced by Bayer Crop Science, will be coming off the market.

Nematodes are parasitic worms that damage the root system of plants, causing patches of yellowing or dying turfgrass. Looking at the roots of nematode-damaged turfgrass, small feeder roots might be gone and root tips appear dead. If new roots begin to grow, they generally are injured as well. It’s this damage to the root system that’s responsible for the yellow or dying patches of grass.

Nemacur has been on the market for 30 years, but will be phased out because of Environmental Protection Agency concerns, according to Bryan Gooch, business manager – insecticides for Bayer.

“In 2002, the EPA assessed the risk associated with the use of Nemacur and determined additional data needs and/or mitigation measures were necessary to support the continued use,” Gooch says. “The expenses required to continue to support the registration were more than Bayer could undertake.”
Enesta Jones, press officer for the U.S. EPA, says the problem with Nemacur, and the active ingredient fenamiphos, has to do with the residue not being safe to golfers and those working golf courses.

A fact sheet provided by Jones states: “The EPA has risk concerns for workers who mix, load, and/or apply fenamiphos to agricultural sites and golf courses.” As for the effects on a person’s health: “Fenamiphos can cause cholinesterase inhibition in humans; that is, it can overstimulate the nervous system causing nausea, dizziness, confusion, and at very high exposures (e.g., accidents or major spills), respiratory paralysis and death.”

However, Nemacur won’t be taken off the shelves immediately. With the help of local superintendents, in particular the Florida Golf Course Superintendents Association, Bayer was able to negotiate a five-year phase out plan, Gooch said.

“Bayer may continue to sell and distribute all Nemacur end-use products until May 31, 2007,” he says. “Distributors may continue to sell Nemacur until May 31, 2008. Use of Nemacur may continue until supplies are depleted, except where prohibited by the label. After May 31, 2005, the label prohibits applications to certain soil types (hydrologic soil group A) that have shallow depth to water table (less than 50 feet deep).

“This restriction on the label is somewhat ambiguous, but certainly doesn’t affect all courses in Florida,” Gooch adds. “Bayer has proactively taken steps to coordinate with the Florida Department of Ag and Consumer Services for their interpretation of the label and published information bulletins to help superintendents learn more about their particular soil type.”

Nematode populations generally are denser and more prevalent in warmer regions, where longer growing seasons extend feeding periods and increase reproductive rates, according to ATTRA – National Sustainable Agricultural Information Service. Light, sandy soils generally harbor larger populations of plant-parasitic nematodes than clay soils. This is attributable to the more efficient aeration of sandy soil.

Plants growing in readily drained soils are more likely to suffer from intermittent drought, and thus are more vulnerable to damage by parasitic nematodes.
Mark Jarrell, CGCS at Palm Beach National Golf and Country Club in Lake Worth, Fla., has been fighting the pests.

“Nematodes are a problem on my golf course,” Jarrell says. “They feed on the contents of root cells similar to the way a mosquito takes blood from a human, destroying the root system in the process if their numbers are high enough.”

Jarrell is dealing with the endoparasitic Lance nematode, which can be more damaging than its ectoparasitic brother. Endoparasitic nematodes live and feed within the tissue of the roots, tubers, buds or seeds, while ectoparasitic nematodes feed externally through plant walls. A single endoparasitic nematode can kill a plant or reduce its productivity, while several hundred ectoparasitic nematodes might feed on a plant without seriously affecting production, according to ATTRA.

In addition to using Nemacur to fight his problem, Jarrell uses the fungicide Heritage.

“Dr. Billy Crow at the University of Florida noticed somewhat better control of Lance nematodes if an application of Heritage was applied prior to the application of the nematicide,” he says, “So I am timing my nematicide applications to follow a systemic product, thinking that this could possibly be irritating the Lance nematodes so they exit the turfgrass roots, making them vulnerable to a nematicide application.”

Bob Flanagan, CGCS at Fort Walton Beach Golf Club in Mary Esther, Fla., says nematodes are a problem on his greens, but he also spot treats tees and other areas as needed. Flanagan has a plan for the day Nemacur is no longer available, but still fears the outcome.

“When Nemacur is taken off the market, unless something is quickly discovered that will control nematodes, my only option is to raise height of cut and try to force root growth with fertilizer,” he says. “This will be a huge problem for us.”

Golf courses won’t be the only entities feeling the pinch with the loss of Nemacur. Gooch says Bayer will have to replace the revenue somehow.
“As with any product that loses sales, it requires additional effort to maintain volume in other areas of the business,” he says.

Gooch says Bayer has a promising new product in development, but gave no indication as to when it would be available to golf course superintendents.
Jarrell is aware of research and development on new products, but shares Flanagan’s concerns about the future without Nemacur.

“There are some promising new nematicides being developed, but until they reach the marketplace and are proven effective, the loss of Nemacur will be devastating,” he says. “The soil fumigant Curfew is currently available and effective, but its application to greens is very expensive and the method too damaging to putting surfaces.”

Jarrell paints a grim picture if superintendents are limited in their battle with nematodes in the future.

“Without effective nematicides, the quality of golf in Florida would dramatically decline.”