The Environment and Pests: Pesticide Use on the Golf Course Part 2 of 3

Golf Courses and the Environment

With very few exceptions, great golf courses are not found in nature. Rather, great golf courses are intended to blend into a natural setting and are intentionally built into the existing environment. Clearly, there is nothing profound or lofty about these statements, but they provide a foundation for understanding how golf courses must be maintained in the state of nature.

The natural environment is a dynamic, powerful, ever-evolving force of creation. Human intervention in the environment takes many forms on the golf course. Cultural and biological interventions include modifying soils or breeding grass species to create desired playing conditions. Mechanical interventions include mowing, which mimics the grazing that grass has evolved to accommodate, or watering to sustain a desired species of grass. And, last but not least, chemical interventions include fungicides, insecticides, and herbicides which keep the natural succession of nature in check—succession that would ultimately return a golf course back into its original, natural state.

The long-term succession of a fertile environment progresses from baren soil; to mosses, sedges, and grasses; to brush and softwoods; to climax forests—as illustrated below. Golf course maintenance essentially attempts to keep this succession arrested in the pure grassland stage of succession, which we must admit is somewhat “unnatural.”

 Pesticides are one tool used to maintain the golf course environment as a permanent grassland. Fungicides prevent turfgrass disease, which keep the grass healthy and prevent “dead spots” where weeds and other unwanted plants could invade. Likewise, insecticides are used to thwart damaging pests. And when invading plants do “take root” herbicides stop the spread. In these ways, pesticides are used to consistently maintain a stand of turf that is acceptable for the golfers over the long-term and against nature’s advances.

This sort of intervention into natural ecological processes has risks and unintended consequences. Creating a monostand of any crop is an invitation to natural enemies to attack. This interrelationship between the cultivated ecosystem and natural pests is best illustrated in the traditional “disease triangle”—below. This illustration shows that three elements must be present for disease or damage to occur.

On golf courses--the susceptible host is turfgrass; the pathogen could be a fungus, insect or weed; and the favorable environment includes moisture, shade, bare ground, soil temperature, nighttime air temperature, humidity, pest migration or mating, etc. If any of the three elements are missing, there will be no disease or pest problem.

Which elements of the “disease triangle” can manager use to control pests and maintain a playable turfgrass? The pests and pathogens are always present and ready to make their move on the host when the environment is favorable. The favorable environment might be unmanageable in case of weather, or it might be modified by correcting shade, cultural practices, or nutrient loads. The host thrives best in its ideal environment.

The golf course manager uses pesticides as an efficient means of reducing or removing the pest or pathogen from the disease triangle to protect the golf course. This is especially the case when it is impossible or impractical to modify the environment or the host plant. Cases in point include…where winter weather is inevitable, snow mold fungicides should be applied; the Japanese Beetle has been flying into our area and growing in population each summer, so an insecticide may be needed to reduce grub/larval damage to the turf; or broadleaf or grassy weeds have invaded thin turf, so an herbicide application is a practical means of reducing weeds that compete with grass.

Potential for Collateral Damage

Even though pesticides reduce damage to the golf course, many golfers are concerned about the potential undesired effects of chemical inputs into the environment. For example, a pesticide could persist in the environment or move off-target into water or air ways. Golf course managers are trained to choose and apply the products in a manner that protects water sources and does not persist in the environment.

Another potential hazard of introducing chemicals into the environment is damage to desired species. The classic example currently in the news is the use of insecticides, which may inadvertently harm pollinators (bees) necessary for vegetable and fruit production.

Even if a pesticide is designed to target specific organisms, closely related species can be adversely affected. An herbicide that kills dicot weeds, but does not damage grass, may very well injure your prize ground cover or wildflowers. A golf course manager must have a solid understanding of the chemicals used and the environmental conditions to reduce any collateral and undesired injury.

Another potential and undesirable effect of using chemicals to manage pests in the environment is “pest resistance.” Very generally defined, pest resistance occurs when a pest to becomes immune or escapes the desired effect of the chemical. There are two pathways of pest resistance: mutations and genetic selection.

With mutation, the pest changes because of genomic changes caused by the chemical. This can be observed when the pest persists, is unaffected by the chemical, and takes on different behavior or morphology. Genetic selection occurs when unaffected organisms escape injury and re-populate the environment. This can be observed when chemical treatments fail to last for their intended duration, because the chemical is only affecting a small segment of the population.

The concept of “resistance” is familiar to most people when it comes to antibiotics administered for treating human diseases. The great fear with antibiotics is “creating super bugs” that resist any antibiotic treatment—like MRSA.  In both humans and plants, resistance requires, judicious use of chemistry, new chemistry, and the potential for “stronger” pests.

Reducing Pesticide Use on the Golf Course

Using pesticides is just one choice a golf course manager has for controlling pests. Another key management option for the golf course manager is controlling the environment which may be favorable to the pest. Common practices to reduce pest problems include, for example:

·        Keep grass dense with water and fertilizer to out-compete some weeds and insect damage.

·        Do not saturate the soil with water, which pushes oxygen out of the soil, weakens the grass, and encourages fungi.

·        Keep the grass dry to discourage fungi.

·        Remove trees to provide more sunlight for photosynthesis and healthy grass.

·        Judiciously water and fertilize the grass—based on measurable standards.

·        Aerate soil to relieve compaction and stimulate soil biology, which leads to healthier grass.

Clearly, the upshot here is that healthy turf is better suited to resist or recover from pest damage.

A more forward-looking approach to reducing pesticide use will be the development and breeding of grass species and other biological advancements that make grass less susceptible or even immune from pest attack, while providing sustainable playing conditions for the golf course. In addition, the time-honored practices of bio-diversity and the re-population of beneficial below-ground and above-ground organisms will also help reduce pesticide use.