FEATURES
Stretch Your Fungicide Investment

by Marcia Passos Duffy
Correct application saves time and money

Photos Courtesy of Syngenta Professional Products.

Superintendents should know how to correctly select the right fungicide for the job. Here, a worker uses a sprayer to spread liquid fungicide.

While there is a plethora of fungicides designed to prevent and cure turf disease outbreaks, having an arsenal of chemicals is often not enough. Golf course superintendents need to know how to select the right fungicide for the job and how to properly apply it so that chemicals do not go to waste.

How fungicides work

For fungal diseases to occur you need presence of three things, which plant pathologists refer to as the “disease triangle”: a fungus, a host (the turf) and the right environmental circumstances (a susceptible plant and warm, moist conditions).

Fungicides work by either preventing the fungi from growing and spreading (protectants or preventative fungicide) or directly killing the fungi (eradicant or curative fungicides).

“The biggest obstacle is making sure you have the correct fungicide for the disease you are trying to manage,” said Joe M. Vargas, professor, department of plant pathology, Michigan State University.

There are two ways of approaching disease management, said Vargas. One is to apply preventative fungicides to prevent disease. The other approach is waiting until the disease occurs and addressing it with curative-type fungicides.

Preventative vs. curative

One advantage of using a preventative fungicide is that less chemical is needed to do the job. There is also less damage to the turf since the disease is prevented from occurring. The downside? You might never have gotten an outbreak in the first place, which means wasted chemicals and time.

You can be more certain you’re doing something worthwhile with a curative, or eradicant application of a fungicide, because you can see the disease and you are doing something to get rid of it.

The downside is that by the time you make the application, the damage is already done—and spreading fast, “Which is often objectionable to the members,” said Vargas.

The right fungicide for the job

Certain diseases lend themselves to either a preventative or curative fungicide. Proper identification of fungi is important when selecting a fungicide. Dollar spot, for example, responds well to curative fungicides, but other diseases, such as brown patch, summer patch, Pythium blight and snow molds, are better addressed with preventative fungicides.

What about skirting the entire identification issue by using broad-spectrum fungicides that addresses a wide range of fungi? Broad-spectrum fungicides, which are often marketed to save the golf course superintendent time and money can work, but the dangers of overuse can be problematic, said Teri Yamada, principal at Canada-based consulting firm, TY Environmental Strategies Ltd. (http://www.tyenviro.com), who worked as head agronomist for the Royal Canadian Golf Association for 18 years.

Use of broad-spectrum fungicides may not address specific problems, ironically, wasting both time and money, said Yamada. In addition, overuse can result in creating resistant strains of fungi, which, he noted, is already happening.

“Broad-spectrum fungicides may stop a wide range of fungi, but overusing [these fungicides] rather than first positively identifying the correct disease organism is not only a waste of product, it can also lead to resistance within the fungal population to that form of fungicide,” said Yamada.

Superintendents should routinely recalibrate spray equipment to make sure they are applying the proper amount.

Know your course’s diseases

The best way to use fungicides is to know your course, and understand which diseases have cropped up in the past.

“Keeping a record of your prior history is important,” said Matt Giese, technical field manager, lawn and garden group, for Syngenta (www.syngenta.com).

Over time, you can plot out the hot spots on your golf course where diseases most often crop up. This takes planning, but it is well worth the time spent, said Giese.

You need to understand not only where diseases are plaguing your golf course, but also what these fungi are and the conditions in which they thrive. Is the disease active in the turf canopy or roots? Is it affected by fertility or moisture levels? Can the problem be remedied by something in the environment, such as increasing air movement, removing dew, increasing sunlight or changing the way the turf is mowed?

“Golf course superintendents should also gauge the level of damage that can be tolerated by the golfers,” said Yamada.

Stay up to date with the varying types of fungicides by talking to your fungicide sales representative. Also, contact your local extension service, which can provide good information about the turf diseases in your region and the products you can use to treat them.

Amount, tools, conditions

Fungicides come in granular and liquid forms. Liquids can be applied with a self-propelled sprayer unit (either a ride-on vehicle or push-type application). Granular forms are distributed using centrifugal spreaders, similar to those used for fertilizers.

Superintendents should routinely recalibrate spray equipment to be sure they are applying the proper amount of product for the area they are spraying. Make sure you replace spray nozzles every year to optimize the spray pattern, suggested Kyle Miller, senior technical specialist with BASF Turf & Ornamentals (www.betterturf.com).

The right nozzle size is important because the size of a spray droplet has a direct influence on the efficacy of the chemicals that are applied.

While overall coverage is important for diseases that are active in the upper part of the turfgrass plant, for root-borne fungi you need to get the fungicide down to the rootzone and a different type of nozzle is required, or the product must be watered in after applying.

Conditions should also be right for application. Fungicides should be applied on a windless day so the fungicide can reach the plant and drift is not an issue. Also, make sure that the leaf surface is dry, and don’t apply fungicide in the hottest part of the day, which can stress the turf.

The best advice: Read the label. “Manu­facturer labels are sometimes overlooked ... so read and follow those suggested spreader settings,” said Giese. “You’ll also find lots of little tips and tricks to make spreading as efficient as possible.”

The author is a freelance writer from Keene, N.H.