March 2011 Articles

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Try non-chemical, enviromentally friendlly weed control

Try non-chemical, environmentally friendly weed control
By LSU AgCenter Horticulturists Dan Gill, Kyle Huffstickler and Allen Owings
Weeds in your flowerbeds and vegetable gardens can be frustrating and sometimes overwhelming to control. Weeds are competitors that deprive your desired plants of water, nutrients and sunlight. That competition can cause desirable plants to become weak so they’re susceptible to insects and disease, resulting in poor performance.
Controlling weeds in the landscape can be difficult, expensive and time-consuming. Using a herbicide to control and manage weeds can be an effective way to approach this task. If used as directed along with an integrated pest management program, herbicides are a safe and effective method to manage and control weeds.
If using herbicides is not your desired method of weed control, the next best alternative is to remove them by hand. Pulling them is a very effective way of controlling certain weeds, such as chamber bitter, crabgrass, purslane and pigweed, can be removed relatively easily by this method. However, deep-rooted grasses like Dallis grass and goosegrass may require the use of a hand trowel or other tool to remove them.
Unfortunately, some weeds are difficult to control just by hand pulling and will come right back rather quickly after they have been removed. For example, perennial weeds, Bermuda grass and purple nutsedge, which is considered to be the number one weed problem in the world, seem to reappear in just a few days.
Bermuda grass produces both stolons and rhizomes that grow above and below the surface of the soil, while purple nutsedge produces a chain of tubers below the soil surface. These underground structures make common Bermuda grass and purple nutsedge difficult to control by pulling because a significant portion of the root system remains in the soil and allows the plants to re-infest landscape beds.
For hand removal to be successful, it is critical to remove weeds when they are young and have a minimal root system. More importantly, remove them before they have a chance to make seed. If a weed is allowed to produce seed and part of the root system is left behind, it will return quickly and in large numbers. Some weeds are heavy seed producers, like crabgrass, which can produce up to 5,000 seeds from a single plant in one growing season. Others, such as pigweed, can produce more than 100,000 seeds per year, and the seeds may remain dormant in the soil for more than 30 years.
Finally, mulch your beds. Mulching your flowerbeds several times a year with organic mulch at a depth of 2-3 inches will help prevent weed seed germination and growth. Organic mulches like pine straw and chipped or shredded pine bark are effective and have been proven to work best in suppressing weeds in the flowerbed. Additionally, mulches help by adding some nutrients and organic matter to the soil as they break down and decompose.
Other ways to control weeds in the landscape is by the use of inorganic mulches such as weed barrier fabrics and plastic films and even newspapers. These mulches work best in suppressing weeds in the vegetable garden.
Using a weed barrier fabric is an effective way of suppressing annual weeds, but it’s ineffective in controlling tough perennial weeds such as torpedo grass, Florida betony or rattlesnake weed, bushkiller vine and purple nutsedge. These weeds are extremely aggressive and will grow through or around these barriers. Trying to control these weeds by hand pulling is virtually impossible because of their root structures and their ability to produce rhizomes and tubers below ground.