Weed Control Tips

Weed control. It seems like a never ending cycle. Each spring and summer, it seems like you are killing the same old weeds you killed last year. You ask yourself, "Will I ever get rid of these blasted weeds?!!" Well, with today's technology and expertise, the answer would be a definite.. maybe! Some herbicides are doing an excellent job of controlling weeds, while some weeds are doing an excellent job of building resistance to herbicides. Biocontrol and mechanical control are effective means of control in certain circumstances. If you learn the principles of weed control and implement an integrated weed management plan, you can turn the answer to your question into a definite yes! Keep at it.

Basic Ingredients

Weed control can be as simple or as complex as you choose. Below is a basic list of chemical and non-chemical equipment that will help you control all your weeds.

Chemical Control

Sprayers

The size of the job determines the size of sprayer you need. Squirt bottles, hand sprayer, ATV sprayers, truck mounted sprayers can be used for jobs from one plant to over one hundred acres.

Calibration

Calibration of equipment is vital to ensure that proper amounts of herbicide are applied. More is not always better in the case of herbicides. In addition to wasting money, you risk harming non-target plants, animals and people. The following is a good link providing simple instructions for calibration: weedalert.com

Chemicals

It's very important to use high quality chemicals. Many chemicals in use today are quite safe for the average person to use, are easy on the environment and devastating to the weeds. Search for the chemical that best suits your needs. There are many available that are selective, killing only broadleaf or only grass; some are nonselective; some sterilize the ground and prevent new growth for up to a year; and some are pre-emergent weed inhibitors. Be certain to follow the chemical label for safety and rates. If you are confused about the vast selection of chemicals, talk to a professional before purchasing.

Surfactant

Nearly as important as the herbicide itself is the use of surfactants. The typical weed leaf is either hairy or waxy. Consequently the water/chemical droplet will ball up or run off prohibiting chemical from entering the plant where it can do its job. Using a surfactant will allow the water/chemical molecules to break down and spread over the leaf surface evenly, penetrating the hairy or waxy leaf surface and entering the plant. There are many commercial grade surfactants available, but for small jobs liquid dish soap may be used.

Safety Clothing

It is very important to use the proper safety equipment while using herbicides. The label on each container of herbicide it states what safety equipment is necessary. ALWAYS READ AND FOLLOW THE CHEMICAL LABEL. Standard things to have are chemical resistant gloves, coveralls, long sleeve shirt, pants, and safety glasses or goggles (see chemical requirements). Leather gloves, short-sleeved shirts, and shorts will not protect you from chemical exposure.

Spraying Methods

Always read and follow application instructions on the label. Be sure to mix the chemical well and agitate periodically while spraying. Use smooth defined motions and follow parallel paths when spraying larger patches of weeds to ensure complete chemical coverage.

Timing

Generally, weed control is most effective when weeds are young and actively growing. Most annuals and biennials respond best to herbicides prior to flower bud stage. However, many perennials are highly vulnerable to herbicide during the flower bud stage and again just after the first killing frost of the fall season. The Montana-Wyoming-Utah Weed Management Handbook is an excellent source of information on herbicide rates and application timing. It is available through your County Extension agent.

Clean up

When you are finished with your weed control project, it is critical to clean your equipment to protect it from corrosion up and to prevent cross contamination of other chemicals you might mix at a later time. Triple rinse empty chemical containers and equipment in a safe area, away from sensitive plants, lakes and streams. Dispose of rinsed chemical containers properly in the landfill.

Non-Chemical Control

Mechanical Control

At times controlling weeds mechanically can be very effective. Many annuals and biennials can be controlled by disking, digging, or pulling. When just a few weeds are a problem you can dig them faster than you could prepare a spraying operation. If the offending weeds are near sensitive areas or people with chemical allergies, digging or hand pulling may be the only option. A good sharp shovel will be the best tool to use because getting the root of the weed is imperative or it will resprout and set seed. *CAUTION* Perennial weeds such as field bindweed (morning glory), Canada thistle, knapweed's, leafy spurge, and perennial grasses will often benefit from disking and digging because they reproduce from broken off rootstock. For these weeds, it is best to combine mechanical control with a vigorous chemical control program.

Biological Control

Biocontrol is a great tool to use especially in sensitive or inaccessible areas or when herbicides are not wanted. Biocontrol's typically include pathogens, insects, and herbivores which prey upon the undesired weed species. In the case of most pathogens and insects, USDA-APHIS tests each species thoroughly for several years to ensure that they are host specific and will not damage non-target plants. Herbivores are trained to select noxious weed species then are controlled by a herder to ensure effective weed control. Biocontrol is a slow and steady approach to weed control. Results often take a year or more to see but are long lasting. Most biocontrol do not and are not intended to eradicate the host weed specie, but rather it is intended to control the noxious weed to a point where it does not damage the native environment. The weed department is currently using biocontrol for leafy spurge, diffuse and spotted knapweed, purple loosestrife, poison hemlock, dyer's woad, and dalmatian toadflax.

Collect Your Own Biological Control

NOTE: It is illegal to transport biocontrol agents across state boundaries without a permit.

Many biocontrol's are easily obtainable simply by going to the areas where they exist. When collecting insects, use a sweep net with tight mesh and sweep through vegetation to collect them by the hundreds. Put the insects in a breathable container and keep them cool until you intend to release them.

Leafy spurge flea beetles are found throughout much of Cache County due to an aggressive introduction campaign by the weed department. There are several varieties of flea beetle in Cache County. The ones you will likely find will be about 1/8" to 3/16" long and be black (Aphthona czwalinea and A. lacertosa) or brown (A. nigriscutis and A. flava). Best time to collect is through the warmest part of the day from late June through mid August.

Knapweed weevils have been introduced into both diffuse and spotted knapweed infestations throughout Cache Valley. They are about 1/8 to 1/4" long and are greenish-gray in color. We have seen good results on the diffuse knapweed areas and mixed results in the spotted knapweed areas. These are relatively new introductions and more time is needed to determine their value.

Yellow starthistle weevil have recently been introduced near Richmond, Utah. It will take some time to see what effect they will have in Cache County.

Poison hemlock moths came to Cache Valley naturally. These moths are quite prolific some years and almost nonexistent in others. When the population is high, look for web-like nests surrounding hemlock flower heads. The caterpillars will totally exfoliate an entire plant leaving only the stems behind.

 

 

Purple loosestrife beetles exist in the lower Little Bear River drainage. They were originally released in the Pelican Pond area and have significantly reduced the loosestrife population in this area. Recently these beetles have spread naturally from Pelican Pond downstream to the north. The beetle population is spread out somewhat and may be difficult to locate.

 

 

Dyer's woad rust is a native pathogen that was discovered in Southern Idaho. It is readily found in most areas where dyer's woad is found. Infected plants are yellowish and puckered. the rust is found on the underside of infected dyer's woad leaves and appears as small dark spots. This rust is collected in the spring by gathering infected plant parts and simply redistributing them to other areas. Moisture and wind are the agents that spread this rust, thus a wet spring is best for moving rust. Rust has limited control on dyer's woad but does limit seed production. Other biological controls are currently being studied.

 

 

 

 

 

 

 

 

If the job is too big or near sensitive areas call a professional for assistance.

Noxious Weed Field Guide for Utah
Weed Distribution Maps