By this time each year, home gardeners and farmers alike can begin to see evidence of some of their mistakes or oversights. This evidence is the appearance of unwanted grasses and weeds in places they are not supposed to be.

Sometimes weather conditions can create a lot of unexpected weed problems. If it is too hot and too dry when herbicides are applied, there may not be enough moisture in the soil to activate the herbicides, so they are degraded by the sunlight before they become effective.

Sometimes too much rain dilutes herbicides, so they are not fully effective or they are removed from the treated areas as the water washes from the field. Sometimes just receiving good summer showers along with mild, night-time temperatures can create ideal environments for weeds, especially if herbicides were not applied or were applied incorrectly.

Agricultural agents on our staff have been receiving quite a few phone calls recently requesting information about how to control various weeds. I am sure there will be many more calls for the next several weeks. Unfortunately, by the time many of the calls are received, the weeds are so large they will be difficult or impossible to control.

There are several factors to remember when trying to manage or control weeds in any environment. First, the weed must be properly identified. All herbicides are designed for specific weeds, and each of them has been thoroughly tested to determine its effectiveness on various weeds. Some herbicides are extremely effective on certain weeds and totally ineffective on other weeds. Before selecting a herbicide, the weed or weeds to be controlled must be properly identified.

Some of the more common weeds are fairly easy to identify, at least by common name. Most farmers and many nonfarmers with gardens and lawns have had enough experience with certain weeds that they not only know the name of the weed, they also know what herbicides are effective at controlling them.

For other weeds, it is fairly easy to get them identified. The agents on our staff have had many years of experience and, during this time, have seen a lot of different weeds. Most times they will be able to identify unusual weeds with no problem. Sometimes they will have to refer to reference books and key the weeds out to determine the exact species. If this fails, they can send the weed to the proper specialist in Raleigh for exact identification.

If you have a weed that you cannot identify, please gather a good sample and bring it to the Extension Center at the O. P. Owens Agriculture Center on Highway 72 West of Lumberton. This sample should include the entire weed when possible, especially flowers if the weed has grown to that stage. Place these samples in a damp paper towel and wrap with newspaper. If properly collected, a sample will remain fresh for several days.

The next important factor for weeds management is selecting the proper herbicide. As mentioned earlier, some herbicides are very effective on certain weeds and not effective on others. Once the weed has been identified, it is much easier to select a herbicide that has been designed to provide control for that weed. Also, consider personal and environmental safety when selecting herbicides. Select the one that provides the greatest safety for the applicator and is least toxic to the environment.

Another factor to consider is the time of application of the herbicide. Most weeds are more easily controlled when they first emerge from the ground. A general rule of thumb is to control weeds before they get four inches tall. Most weeds are much easier to control when they are young and actively growing, but there are exceptions to this.

Some weeds must be allowed to grow to a certain size before herbicides are applied. A good example of this is common Bermuda grass. This grass should be allowed to grow until the runners are about four to six inches in length. This will provide greater leaf surface for the herbicides to contact and will, therefore, provide greater control.

The final factor to consider is the method of application of the herbicide. Some herbicides should be applied in coarse sprays, others in very fine sprays. The herbicides should be mixed with enough water to provide good coverage without washing the herbicide off the leaf of the plant. Some herbicides require the addition of a surfactant, or sticker, to make it stick to the leaf surface.

Weed control should not be a difficult task if done properly. For more information please contact your Extension Center.

E-mail address: Everett_Davis@ncsu.edu

Mailing Address:
P. O. Box 2280
Lumberton, NC 28359-2280

Phone: 910-671-3276
Fax: 910-671-6278

Date Created 09/13/01