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PROBLEM WEEDS
CONTROLING PROBLEM WEEDS CAN SAVE MONEY INCREASE GRASS PRODUCTION
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Quick Facts...
- Weed management means developing a control plan to implement over time.
- Prevention, eradication and control are three general management strategies.
- Prevention is the first line of defense to keep weeds from occurring or increasing.
- Eradication is the removal of weeds from an area so they will not recur unless reintroduced.
- Control reduces a weed population to a level where you can make a living off of or enjoy using the land.
- A weed management system integrates two or more methods into a plan of operation.
Prevention
Prevention keeps weeds from occurring or increasing in an area. Preventive techniques include planting high quality, weed-free crops or grass seed. Legislative items, such as clean-seed acts and weed-management laws, also can help stop weed problems before they occur or may deter weed spread.
An important preventive measure related to control is to keep weeds from going to seed. This is important for annuals and biennials, because that is the only way they reproduce. Perennials reproduce from seed, as well as vegetatively from their root systems. Annual weeds live for one growing season, biennials for two and perennials more than two. However, preventing seed set is extremely important to keep perennials from starting new infestations some distance from existing ones.
Eradication
Eradication is the removal of weeds from an area so they will not recur unless reintroduced. If eradication creates an open area, one weed problem may be cured simply to create another one. If eradication is necessary, re vegetate the ground to prevent another weed infestation. Eradication is desirable for small patches, 10 to 100 feet in diameter, but not always for larger ones.
Control
Control, the most common management strategy, reduces a weed population to a level where you can make a living off of or enjoy using the land. Adequate control also may prevent future infestations. There are four control methods: cultural, mechanical, biological and chemical.
Cultural control methods promote growth of desirable plants. Fertilization, irrigation and planting at optimum densities let crops compete with weeds and not with each other. While nitrogen fertilization increases yields in grass hay meadows, it also fosters weed establishment and growth. Fertilize cautiously, especially with nitrogen, and only when necessary as determined by soil testing.
Mechanical control methods physically disrupt weed growth. This is the oldest control method and is used most often worldwide. Tillage, hoeing, hand-pulling, mowing and burning are examples. To mulch or smother weeds often is considered mechanical, even though it simply excludes light rather than physically disrupting weed growth.
Biological control methods use an organism to disrupt weed growth. Often the organism is an insect or disease and a natural enemy of the weed. This is called classical biological control. Classical is not the only form of biological control. Livestock can be effective weed-management tools if used correctly. However, improper livestock management (overgrazing) can be extremely damaging to the environment and exacerbate weed problems.
Chemical control methods use herbicides to disrupt weed growth. The first rule of any pesticide use is to read the label before using the product and follow all directions and precautions. (NOTE: Avoid using soil-active herbicides, such as Tordon, Vanquish/Clarity or Telar, near windbreak plantings and other desirable woody vegetation. Plant injury or death can occur. Do not allow any herbicide to drift onto woody or other desirable vegetation for the same reason.)
Weed Management Systems
A weed management system uses two or more control methods. The key is to encourage desirable plant growth with optimum fertilization, when necessary, and/or irrigation (cultural control). Plant competition is an often overlooked tool and should be used first, but not exclusively. When enlargement of the desirable plant community is necessary, make sure you seed at optimum rates to ensure establishment and subsequent competition with weeds. Generally, perennial, sod-forming grasses compete best with weeds.
Till, hoe, hand-pull, mow or mulch (mechanical control) if desired. Herbicides (chemical control) are powerful tools that should be used judiciously, not exclusively. Unfortunately, too often herbicides are used to make up for poor cultural or mechanical management decisions. Herbicides may be a component of the weed-management system. Biological controls can also be part of a system. Several natural enemies currently are available from the Colorado Department of Agriculture. Livestock grazing can be effective, depending on the weed species, if the livestock are properly managed for weed control.
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