Author Topic: Introduction to Cultural Control  (Read 1898 times)


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Introduction to Cultural Control
« on: April 28, 2011, 05:20:27 PM »
Proper watering prevents weed germination and slows weed growth. Lawns and turf need one inch of water per week, and rainfall often meets that need. Use a rain gauge, a small bucket or a coffee can to measure rainfall. If watering is necessary, check the client?s irrigation system to make sure automatic sprinklers are set to water heavily once a week, not lightly every day. Light watering promotes shallow root growth and weak turf.

Mow high, 3 to 3-1/2 inches if possible. Taller grass shades out weeds and keeps moisture in the soil. To reduce grass stress, remove no more than one-third of the grass blade when mowing. Keep the mower blade sharp. Clean the mower blade between jobs to avoid transferring weed seeds to other properties. For athletic fields, try to find periods of time between games or in the off season when the grass can be allowed to grow to 3 inches.

Soil Adjustments
The chapter on soil health, fertility and amendments extensively covers methods to optimize soil for growing turfgrass.  
Healthy soil enables turfgrass to out-compete weeds so that, over time, grass replaces weeds.

Weed Lifecycles
Another key to weed control is timing. Careful observation of weed populations and weed seedling emergence patterns will help the lawn care professional develop an appropriate weed control program.

Corn gluten can be used as a pre-emergent. It is applied to a lawn in the spring between forsythia and lilac bloom to help prevent germination of crabgrass and other annual weeds. It also prevents turfgrass from germinating, so do not seed on top of corn gluten. If necessary, you can apply two inches of compost over corn gluten and then seed.

Corn gluten is high in protein and contains about 10 percent nitrogen. Because corn gluten is high in nitrogen, be sure to reduce subsequent fertilizer applications accordingly. High nitrogen conditions can harm some grasses such as fine fescues, promote certain fungal diseases and increase insect and herbivore damage.

Careful mechanical cultivation (for dense weed infestations) or hand pulling (for minor weed problems) during periods of active growth also prevents the formation of large weed populations. Regularly inspect a lawn or field to determine what weeds are growing where and when they appear.

Annual weeds grow, flower and produce seed in a single season and will die at the end of the season. For this reason, it is easier to start a new lawn in the fall, when the weather is cool, annual weeds are dying and the cool season turf grasses can start with little or no competition.

Spot Control
For lawns or turf with weed issues, use organic methods that fit the problem. Hand-pick or selectively remove weeds for sparse or small infestations. For larger areas, weeding can be accomplished using a liquid organic herbicide (they typically contain acetic acid, clove oil and/or citric acid), a hot foam sprayer or a weed burner. These methods work by immediately killing the aboveground portion of the weed; they will also kill any grass or other plant they come in contact with. Mechanical cultivation (rake, hoe or rototiller) is also an option. Seed immediately following spot control so turf grass can fill the space left by the weeds. Often, certain types of weeds will take over a particular area of a lawn or turf and can be managed once or twice a year with soil amendments to correct the soil imbalance found in that particular area.