Tooele Transcript Bulletin – News in Tooele, Utah

May 9, 2013
Variety of methods available for weed management

The intermittent nice weather of spring presents the opportunity to do some early season weed control. Spring weather tends to bring an onslaught of weeds from seeds that have lain dormant through the winter. Weeds are opportunists.

When the weather begins to warm and the sun begins to shine, they waste no time in starting to grow. In fact they tend to grow much better than the plants that we place in our gardens and landscapes.

Gardeners who declare war on weeds have a much better chance of raising attractive flowerbeds and bounteous gardens. Weeds are great competitors — usually better than the domestic crops we choose to grow. In the course of growing they quickly use water and nutrients that the crops need to grow well. They generally grow large quickly and shade out the other plants as well. It is important to keep weeds under control for the sake of other garden plants.

A little grooming with a hoe will quickly take care of seedling weeds.  If they are allowed to grow bigger, they develop a root system that becomes harder to disrupt. If you visit your garden each day with a hoe in your hand, you will likely be able to keep the weeds under control.

Hoes of various designs are very effective for weed control, but sometimes it is more convenient to spray weeds using herbicides.

One major advantage of using a hoe or digging tool to remove weeds is that timing is not critical. You can go out and work on taking out weeds in any kind of weather or time of day. The ideal time to hoe out weeds is while they are small. You can scrape the hoe through the surface of the ground and quickly remove tiny weeds. If you wait, the job becomes more difficult.

If you plan to do some spraying for weeds, check the thermometer and weather forecast. Winds or even small breezes can carry sprays to damage other plants nearby. Heat volatilizes sprays like 2,4-D and the fumes drift to damage other plants as well. The spray remains a concern for several days so if  the weather is predicted to go above 80 degrees in the next four or five days, do not spray using herbicides.

Pesticides can be harmful to humans and pets. Insecticides can be a particular problem, but you should also wear protective clothing when you are spraying weeds. Change clothes and clean up after spraying and keep pets and children off of treated areas for a day or so.

Always read label directions for specific safety precautions and application rates.

Eliminate 98 percent of the pesticide exposure by simply wearing a long-sleeved shirt and chemically resistant gloves.  When mixing pesticides, 85 percent of the exposure occurs on hands and 13 percent on forearms.  Wear a shirt made of tightly woven fabric with long sleeves. Wash it and any other clothing separately from the rest of your laundry. Be sure to wear any other protective equipment specified on the label.

Other gardening methods help control weeds while encouraging the growth of more desirable plants.

Drip systems save water by putting it directly on the roots of the plants you want to grow and not in surrounding soil where weeds might grow.

Ground covers are excellent weed barriers. Some are better than others and they can result in a ten-fold reduction in evaporative water loss from soil at the same time.

Black plastic is a favorite ground cover for weed control. It covers the weeds so they don’t get the sunlight needed to grow. This is particularly effective for perennial weeds like field bindweed, quack grass and white top.

Organic mulch is another good control, particularly around perennials. Using 3 or 4 inches of composted bark or similar product to shade out weeds and keep them at bay is a good idea. As the season progresses, mulch begins to break down and can be worked into the soil as an enrichment for the following year to enhance soil structure, increase soil fertility and prevent compaction.

Using such materials is a great way to recycle yard waste such as pruned woody materials, fallen leaves and needles and grass clippings. To be effective, these materials must be made up of particles larger than the underlying soil particles. They should be more than a half-inch in diameter.

Such materials must be free from weed seeds, disease causing organisms, pesticide and herbicide residues.

It is still possible to use materials that don’t fit these criteria, but compost them thoroughly before using them. Proper composting results in controlled decomposition of organic materials and generates enough heat to kill weed seeds and disease organisms. It also helps break down pesticides that can injure growing plants.

As organic mulches decompose, they use nitrogen and may lead to nitrogen-deficient plants. If the older leaves on plants begin to yellow and the plant’s vigor decreases, add nitrogen to replace that lost to mulch decomposition. Add it at a rate of one to two pounds of actual nitrogen per 1,000 square feet.

Many people use chunks of bark, gravel or rocks to mulch the soil. While these are fairly effective, some weeds do eventually grow through and become much harder to remove than those that grow in soil. Putting heavy-duty plastic beneath the mulch helps but if you are growing plants in the area, the plastic must have holes to allow water to penetrate to the roots.

Inorganic mulches like cobblestones are most effective on walkways and driving areas.

Ground cloth is somewhat effective, particularly for the first year or two. Eventually weeds do begin to grow through it and they are hard to remove.

Using such precautions will help keep the weeds under control, but there are some perennial weeds that are uncommonly difficult to control. Future columns will discuss how to control these weeds.

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