Feature Articles

Insect and weed control

Pesticides — or alternatives

By Deb Risden

The National Institute of Environmental Health Sciences defines pesticides as any compound intended to kill, repel or control animal and plant life that damage or are a nuisance in agriculture or domestic life. Pesticides include herbicides that destroy or control weeds; insecticides that control insects; and fungicides that control fungi. The NIEHS reports that more than 800 pesticides are registered in the United States. 

The International Union of Pure and Applied Chemistry reports the first recorded use of insecticides is about 4,500 years ago in Sumaria for the purpose of protecting crops using sulfur compounds, and about 3,200 years ago in China using mercury and arsenic compounds. Inexpensive synthetic products were introduced in the 1940s and became widely used. New compounds were introduced over the next few decades and continue today.

Pesticide use is not without health risk to humans. The Environmental Protection Agency is responsible for evaluating pesticide risk to humans and approving pesticides. It states, “Many pesticides can also pose risks to people. Generally, however, people are likely to be exposed to only very small amounts of a pesticide — too small to pose a risk. To determine risk, one must consider both the toxicity or hazard of the pesticide and the likelihood of exposure. A low level of exposure to a very toxic pesticide may be no more dangerous than a high level of exposure to a relatively low toxicity pesticide, for example.” 

The EPA reports that the effects of insecticides on humans depend on the type of pesticide. “One notable pesticide, DDT, was used to control mosquitoes carrying malaria, typhus and even bed bugs. However, it was banned in 1972 by the Environmental Protection Agency due to its declining benefits and increased environmental risks and toxicity.” 

The NIEHS cites many studies that show an increased risk of developing autoimmunity, kidney disease and kidney cancer, increased risk of shingles, thyroid disease and thyroid cancer and Parkinson’s disease. The Centers for Disease Control and Prevention reports anywhere from minor effects such as skin irritation, cough and drowsiness to moderate effects such as a high fever, disorientation and low blood pressure to major effects such as seizures, cardiac arrest and respiratory arrest. 

According to the website of Beyond Pesticides, a nonprofit organization that works with governments, nonprofits and users of natural resources to reduce the need for unnecessary pesticide use, exposure to pesticides causes harm even when used in reportedly safe amounts directed by the EPA. Also stated on the website, “Acute and chronic exposure to chemicals like pesticides can cause a range of harmful effects. Even use in accordance with the pesticide product label directions can cause or promote cancer, neurotoxicity/developmental and learning disabilities, reproductive and birth defects, respiratory illnesses, endocrine/immune disruption, skin irritation/headaches/disorientation. Additionally, exposure to these toxic pesticides can weaken the body’s immune response to illnesses and initiate or promote underlying conditions and vulnerabilities — like respiratory issues such as asthma or endocrine disruption problems like diabetes.”

There are alternatives to pesticides for homeowners.

Allisa Linfield, horticulture program coordinator, Colorado State University Extension, El Paso County office, said the CSU Extension assists citizens in management strategies of pests in the garden and home. “Managing certain plants in the landscape will often need multiple strategies. Some could be chemical, but there are some that are biological or mechanical,” Linfield said. Mechanical methods are physical methods such as hand weeding, hosing down plants to remove insects, pruning and using mulch. Biological methods are the use of beneficial organisms that might be natural predators such as ladybugs that control aphids, rootworms, spider mites and weevils. 

“Choosing the method depends on the plant in question,” Linfield said. “There is a point whether it’s a pest that’s an insect or a pathogen, where it makes an impact on the plant that as a gardener or a homeowner you might not like the way it looks. If it’s not causing any impact that bothers you, we might not recommend any strategy unless it becomes a bigger problem down the road.” An example is the black larvae (caterpillars) that become brush beetle. Rabbitbrush serves as host to the larvae. “It’s a native insect on a native plant so it’s not invasive. It may cause temporary issues for a plant,” she said.

“Proper management of a plant, making sure it gets enough water and space in the landscape can prevent pathogens and insects. It’s a form of prevention,” she said. When planting a garden, it is important to use native plants to keep unwanted pests at bay, Linfield said. 

“Making the right plant choices in the beginning always helps control noxious weeds,” said Nicholas Daniel, noxious weed specialist, El Paso County Community Services Department, Environmental Division. “I always suggest that people look at the native plants around the county and using those on their properties, such as native grasses and shrubs. They will out compete these weeds,” he said. Daniel said the EPC Conservation District, the Kiowa Conservation District and the Double El Conservation District can help homeowners put together seed mixes specific to areas in the county. 

“The biggest thing is to not get frustrated. Weeds happen to all of us,” Daniel said. “The first step is to correctly identify the weed. I can assist any EPC resident with identification and management strategies. They can email me pictures of the weed.” Daniel said once the weed has been properly identified, the homeowner can decide how aggressive the infestation is and determine the next steps. 

If people want to avoid using herbicides, Daniel suggested starting with mechanical solutions such as repeated mowing and clipping seed heads. “Start at the edge of the weed area and work your way into the center of it during the course of two to three years,” he said. “Sometimes, my only suggestion is to use herbicides, but I’m always willing to work with anyone on a management strategy that speaks to them and their property.”

Daniel said the county has an established successful biological control program. For example, for yellow dalmatian toadflax, the county uses a weevil to help control it. “We use a lot of biocontrols for different knapweeds with good success,” he said. Biocontrols are tested over a minimum of a decade by the state to ensure they won’t spread to native species. “They are extremely host specific and once the population is gone, they go to the next population of the weed or they die.”

The county uses herbicides in some situations, especially when there are no biological control solutions. “The biggest concern with herbicides is environmental protection, especially with surface water,” said Daniel. “It’s a very common misconception that these pesticides are deadly to humans and mammals when many of them are not. There’s no doubt indirectly applied herbicides can be detrimental to humans, birds, water and soils, but if people follow the label instructions to a T, they are very safe and effective forms of control.” 

Horticultural vinegar is an alternative to herbicides. Daniel said, “It’s white vinegar at very high concentrations. It will kill any plant it is sprayed on so it’s best to use it in rock areas or sidewalk and driveway cracks.” It can be purchased at home improvement stores. 

CSU Extension has both an in-person and virtual help desk to assist citizens with gardening questions. Detailed information about gardening and pest control can be found on their website at

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