What Is A Weed?

What is a weed?
“A plants whose virtues have not yet been discovered”
- Poet Ralph Waldo Emerson -

I'm sure Emerson would agree dandelions and clover in the center of a green could reduce accurate ball roll, therefore have no purpose and compromise the playability function of the turfgrass. However, weed control on a golf course is not restricted to turf playing surfaces (yet! Although I believe the Pesticide Ban in Ontario deals with "Playing Surfaces") much of the weed control on golf courses can take place in non-play turf zones, mostly due to aesthetics and a misconception of what is and what is not a weed.

Weeds are commonly defined as plants that grow in areas that we don’t want them to. In the past that would mean any plant other than an annual in a garden or a variety of turf grass would be eliminated. That’s fine if golf courses were excluded from the surrounding eco-system, but they’re not. The large monoculture of limited variety turf grasses makes golf courses vulnerable to insect and disease infestations because of the lack of biodiversity that would normally control un-natural numbers. Because of this susceptibility to pests it’s in a golf courses best interest to have a diverse landscape and preserve the natural flora which is suited to keep natural pest numbers down.

Many of the native plants that are commonly referred to as weeds are perfectly suited to attract Beneficial Predatory Insects (BPI’s) that prey upon common turf pests. This characteristic of native flora is being employed by some of golf’s finest designers. In 1999 Jack Nicklaus and Jerome Osentowski had incorporated a new idea of Integrated Pest Management, “bio-islands”, into the design at the 18 hole signature Roaring Fork Club located just outside of Aspen Colorado. The bio-island concept capitalizes on native pollinators and BPI’s by attracting and supporting local populations in the interest of offsetting the monoculture effect discussed in the previous paragraph. The plants chosen were a mixture of native wildflowers and shrubs planted in immense gardens located within the golf course infrastructure. More info on this project go here.

Side note: I spoke with Jerome Osentowski about the success of bio-islands, we discussed the various strategies and success stories of bio-islands at a number of west coast properties. However this year's insect inventories are extremely low due to the epidemic of Colony Collapse Disorder. CCD has virtually wiped out the pollinators in many Western U.S. states, primarily the Native and European bees. This is an extremely serious environmental and economic issue as the potential side effects are catastrophic to the ecosystem and food crops. For more information on CCD go to http://maarec.cas.psu.edu/ , or check out Mike Vogt's post about it here, or if you are interested in Jerome’s work go to www.crmpi.com.

To better clarify the definition of a weed we must take into consideration the bioregional origin of the plant. A native plant is one that historically occurs within the boundaries of a given area and is compatible with plants that coexist within the same habitat. An exotic is a species that has been introduced into a range that it had not naturally migrated too. They may be introduced as a horticultural or agricultural specimen, or could be brought in accidentally. An exotic that can successfully reproduce and persist in the wild is considered a naturalized specie; Queen Anne’s Lace is a great example. An invasive plant is one that is difficult to control and can overbear natural plant communities.

Some natives can be considered invasive under special circumstances, such as Staghorn Sumac or various Poplar species that can overpower disturbed urban areas. Likewise some natives can be considered harmful to golfers and employees as they pose irritations such as allergy related threats - Rag Weed contributes to hay fever (NOT GOLDEN ROD!), and some species pose threats of skin irritation like Poison Ivy.

Evolutionary ecologists believe that plants develop these characteristics in order to prevent further disturbances to the soil or the environment. For example Thistles tend to grow in compacted soils and these plants have developed spiky armor in order to make it uncomfortable for future compactors, such as livestock or heavy mowers. Similarly it’s important to acknowledge that these plants pop up when the appropriate conditions exist for their populations to occur. For example many of our “weeds” can be used as indicator species, meaning that they tell us that the soil is deprived of certain nutrients or higher in others. For example Mullen tends to grow in soils that are fairly depleted of N, P, and K, usually the result of direct solar radiation exposure. Take a look at areas around your golf course/property that contain Mullen, have they been disturbed in the past five years?

For more information about native plants and potential weed species check out the following web sources:

North American Native Plant Society
Centre for Land and Water Stewardship
Conservation Ontario
Ducks Unlimited Ontario
Forest Gene Conservation Association
Agricultural weed index

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