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Weed Control: Man vs. Nature

Katherine Woodford | Weed and Pest Control



According to The American Nursery
and Landscape Association?s poll,
conducted by the Gallup Organization, $16.8 billion was spent in 1998 on landscapes, lawns, and trees. More than $7.9 billion of that was for lawn and landscape maintenance. With this amount of money being spent annually, the professional landscape contractor has to be able to produce the customer?s desired results. One of a contractor?s biggest challenges is to control
public enemy #1, weeds!

Webster?s definition of a weed is ?an unwanted plant: a plant, especially a wild plant, growing where it is not wanted.? Ralph Waldo Emerson defined a weed as ?a plant whose virtues have not been discovered.? However, neither Webster nor Emerson was a professional contractor, and to a contractor in the green industry today, weeds are a fact of life, a virtual thorn in their side. Fortunately, there are many choices available on the market today to control weeds, organic and otherwise, allowing the sharp contractor to stay on top of the balancing act between man and nature.

The ingredients for a healthy turf are the proper amounts of sun, water, and nutrients. When an optimal environment is provided for the turf, the deeper and thicker the root system will become reducing the chance of weeds popping up. Most weeds need light to germinate, and a thick, dense turf automatically excludes them. Thatch will not be a problem if a mulching mower is used. Leaving the top layer of grass mulched on the ground allows natural nutrients to build up.

An additional issue is the height of the grass. Mowing too close can ruin the crown of the grass plant, exposing the soil to light, giving weed seeds an edge, and allowing them to germinate.

Choosing the proper balance of fertilizer is one of the tricks of the trade. There are different formulas available for use for the different seasons throughout the year. Nitrogen is necessary for top growth and greening up the turf.

Phosphorus and potassium are necessary to encourage stronger roots.
The proper pH is another significant factor in getting the most ?bang for your buck? from your fertilizer applications. Generally, soils east of the Mississippi River and in the Pacific Northwest tend to be acidic (below 7.0), while those in the Plains states, Rocky Mountain region, and Southwest are usually alkaline (above 7.0). Most grasses flourish in soils that are mildly acidic, 6.0-7.0. This is easily tested and is just as easily adjusted by either adding lime to raise the pH or sulfur to lower the pH.

When it comes to choosing herbicides, the contractor normally has to determine the problem and purchase the control product that addresses his particular weed problem. There are two categories of weeds: broadleaf weeds and grassy weeds. There are products available on the market to control both of these types of weeds. Most herbicides are of the post-emergent type ? we put the controls down after the weeds emerge. Common ingredients for the control of broad-leaf weeds are: 2-4-D, Clopyralid, and Dicambe. Grassy weeds such as crabgrass are usually controlled with a pre-emergent herbicide.

Michael Hofman of Janet Moyer Landscapes in San Francisco says, ?In an ethereal sense, weeds are a plant out of place and a weed is only in the eye of the beholder. But in the ornamental landscape industry, what we are trying to do is bend nature to our will.?

Keeping in mind that if the turf and bedding plants are healthy and vigorous, they will provide greater competition for the weeds. Hofman?s company takes a ?multi-pronged? approach in dealing with weeds in the landscaping. First, they try to educate their clients in an attempt to raise their tolerance level to the acceptance that a few weeds are okay. They deem that if the rest of the landscape looks exceptional, then people are not going to take notice of a few weeds in the shrub beds. Hofman says he reminds his clients that since they do have a ?slice of nature? in their backyard, they need to remember that in nature, there are weeds.

The second thing they do is take a very strong ?cultural approach? to weed control; they use a great deal of mulch, use drip irrigation in all planting beds, minimizing the amount of water that weeds get, and they ensure that additional weed seeds are not allowed to be present by removing any weeds before they have a chance to go to seed.

The third approach is control products. Because of their location, they have to be especially cautious of the products they use as the water run-off heads straight into the bay. In situations where these products are necessary, they use the least toxic approach. Instead of using a pre-emergent or weed and feed, they prefer to spot treat the turf and flowerbeds.

However, if a bed is being overrun by weeds, herbicide sprays are used to eradicate the situation.
Hofman highly recommends the use of a mulching mower. Before they started using mulching mowers, a monthly application of fertilizer on their client?s lawn was standard procedure; They didn?t follow the feast/ famine method of the ?four times a year plan.? Ever since they have been using mulching mowers, they fertilize no more than three times a year.

?I believe that using a broad based approach to herbicide management, is kind of like shooting an ant with a shotgun.? Hofman?s concern over the environment is personal, but is shared by many contractors. One reason for this may be the regulations many states attach to their contractor?s license.
In California, for instance, every person who applies control products ?for hire? is required to be licensed. Each year they have to be inspected; they have to get licensed in the counties that they are working in; and they have to send in monthly use reports. Certain control products, classified as Category 1 Herbicides, require that 24 hours prior to a scheduled application, a ?request to apply? must be submitted. It could possibly be denied or an onsite inspection may be required. Most states have their own ?IPM? programs, Integrated Pest Management, and their standards will vary.

Gary Krause of Gary Krause Landscaping located in Jacksonville, Oregon, does not agree that a weed is a plant in the wrong place. ?A weed is a pest. Weeds are in the pest management program. A weed is a noxious plant that will compete for soil, moisture, and nutrients with the plants that you are trying to cultivate,? he emphasizes.

Krause?s approach to weed control is very similar to Hofman?s. He recommends against the use of herbicides in a flowering plant bed. ?They have to be hand, mechanically weeded. If not, when the seasons change and you go to plant a different plant, it may be sensitive to the herbicide, causing poor growth or death.?

Locality plays a big part in the technique of choice by the contractor when faced with a neglected turf or an upstart turf. Very often when establishing a new turf, the grade has to be changed. The more you turn the soil, the more weed seeds you bring to the surface. In such cases, an approach used by some contractors is to remove a three-foot layer of the soil and fill it back in with topsoil and amenities. There are problems attached to this, the major one being the expense, especially for those working in an urban area like Michael Hofman.
?Sometimes our access to the backyard is through our clients? white carpeted floors and the doorway is less than three feet wide,? says Hofman, ?so small that you can?t even get a wheelbarrow through there.? So, in many cases it?s not physically possible to take a bulldozer in, haul the soil away and bring truckloads of new soil in.

And it would be senseless to try to do it all by hand.

The second problem is that if you don?t add some of the original soil back in with the new soil, there will be problems with planting trees and shrubs. These new plants generally prefer the new soil with all of its amenities and when their roots hit the ?hard pan,? or the original soil they will start spreading out, creating an unhealthy, shallow root system.

Krause has more choices when establishing a new healthy lawn. He?s able to use the equipment needed to move dirt. Generally, he will start with a rough sub-grade. He brings in fill dirt to establish the sub-grade, then four to six inches of topsoil that?s been amended with enough organic material to make the soil extremely viable and nutrient filled. He uses this to finish the final grading. The finishing touch is to put down sod. Should a little spot of weeds pop up, though, Krause recommends taking a little shaker can of weed control and shake just enough for that one spot. He also recommends that every two years the lawn should be mulched with sterile, bagged manure, raked in. This rebuilds the soil, allowing the grass to grow higher.

It is not always financially feasible to use hand labor to control weeds, just as it is not always physically feasible to use herbicides. Thus, the balancing act between man and nature referred to earlier. Common sense is the professional contractor?s greatest asset. Environmental concerns, and most importantly, staying informed about new and improved control products introduced on the market will lead to success and the end-result will be satisfied clients.

April 2001


 
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