The Disadvantages of Herbicides

Herbicides are advantageous for gardeners and homeowners who want to kill unwanted plants with the least amount of physical labor. Herbicides are used in landscapes throughout North America and are generally safe. Improper use or overuse, however, can result in health and environmental risks and disadvantages that may make some gardeners think twice before using an herbicide product.

Health Risks

Most herbicides pose a significant health risk to both humans and pets if the chemical substances are breathed or ingested, or if they come in contact with skin. Symptoms vary according to the substance, but they may include skin irritations and gastrointestinal discomfort. Individuals who breath, eat or get sprayed with herbicide should call a poison control center at 800-222-1222.

Non-Selective Vegetation Removal

Some types of herbicides are non-selective. This means the chemicals kill all types of vegetation, not just weeds. When using a non-selective herbicide, gardeners should avoid spraying the product on plants they wish to keep. In addition, applications should be avoided when it is windy, since breeze can cause the herbicide spray to drift onto non-target plants.

Persistence in Soil

Some herbicides persist in the soil long after they are applied and can cause lasting effects on future vegetation growth. This may be beneficial if you want to keep weeds at bay, but it may be a disadvantage if you are trying to grow a crop or ornamental plants. Example herbicides with persistent characteristics include some types of uracils, dinitroanilines, triazines and phenylureas, according to Penn State University. Gardeners should always apply an herbicide according to its label. Overuse or improper timing are common reasons for herbicides to persist in the ground, according to Penn State.

Water Runoff

Rain or irrigation can sometimes carry herbicides into unintended areas. This is problematic when the herbicides enter waterways. Herbicides not intended for aquatic use can have detrimental effects on fish, amphibians and aquatic vegetation. Even herbicides intended for aquatic use can have a detrimental effect on the water. For example, the glyphosate-based products have "inevitable" reduction effects on aquatic population levels according to a 2005 study published in the Reviews of Environmental Contamination and Toxicology journal.

Weed Resistance

Repeated use of a specific herbicide can create weed resistance to the chemical. If resistant, the weeds will no longer respond to the herbicide's active properties.