What are pesticides?
Pesticides are products, natural or synthetic, that are designed to kill, prevent, repel, or mitigate pests. A pest may be a weed, a problematic insect, a problematic mammal or other type of animal, a fungus, or another type of living organism.
Sub-categories of pesticides include herbicide, insecticide, rodenticide, fungicide, and more. When you see the suffix “cide” it typically means “act of killing”. So you may imagine then, that an algaecide is something used to kill algae.
Pesticides come in various forms, including liquids, powders, granules, traps (sticky, pheromone, or otherwise), biological, and other forms.
What is interesting to note is that some products we may consider “organic” or “natural” alternatives to synthetic chemical pesticides are still pesticides due to their application. So when horticultural grade vinegar is applied to weeds to burn them, it is a pesticide due to its application. Just because the product is natural, does not always mean it is better or safer; applying horticultural grade vinegar will kill a weed, but it may also kill living organisms in the soil due to its strong acidity.
What are pests?
The EPA defines pests as “living organisms that occur where they are not wanted or that cause damage to crops or humans or other animals”.
For example in the landscape, some may consider Burning Bush an ornamental plant, but when it escapes cultivation and takes over woodland understories, it is then considered a pest (which is why it is preferable not to plant it in the first place!).
More generally speaking, some plants (weeds), fungi, insects, bacteria, or animals may have a damaging affect to our cultivated landscapes or to the natural areas for which we care.
Insects are often immediately viewed as pests, particularly if they aren’t as pretty as butterflies and bees. However, keep in mind that some insects are beneficial. The larval stages of ladybugs look nothing like the adults we’ve come to recognize, in fact, they’re kind of scary looking. The larval stage of a ladybug happens to be much more effective at eating pest aphids than the adults though, so the last thing you want to do is kill them.
And then if you do decide to treat for aphids make sure you’re not accidentally contacting other beneficial insects that may be nearby like ladybugs, green lacewing eggs, bees, or caterpillars.
Why are pesticides used?
There are many reasons people reach for pesticides, some include:
- The pest has lost its natural predator or check
- The environment has become favorable to the pest
- The pest grows or reproduces faster than it can be controlled by other means
- The area is too large to control with other measures
- Other methods of control are cost prohibitive
- The organism has been incorrectly identified as a pest
What is IPM?
Integrated Pest Management is an environmentally sensitive approach to managing pests using knowledge about the pest’s life cycle to use the least toxic means to effectively manage or control it.
The US Environmental Protection Agency defines four steps to IPM:
Set Action Thresholds
Before taking any pest control action, IPM first sets an action threshold, a point at which pest populations or environmental conditions indicate that pest control action must be taken. Sighting a single pest does not always mean control is needed. The level at which pests will either become an economic threat is critical to guide future pest control decisions.
Monitor and Identify Pests
Not all insects, weeds, and other living organisms require control. Many organisms are innocuous, and some are even beneficial. IPM programs work to monitor for pests and identify them accurately, so that appropriate control decisions can be made in conjunction with action thresholds. This monitoring and identification removes the possibility that pesticides will be used when they are not really needed or that the wrong kind of pesticide will be used.
As a first line of pest control, IPM programs work to manage the [landscape], crop, lawn, or indoor space to prevent pests from becoming a threat. In an agricultural crop, this may mean using cultural methods, such as rotating between different crops, selecting pest-resistant varieties, and planting pest-free rootstock. These control methods can be very effective and cost-efficient and present little to no risk to people or the environment.
Once monitoring, identification, and action thresholds indicate that pest control is required, and preventive methods are no longer effective or available, IPM programs then evaluate the proper control method both for effectiveness and risk. Effective, less risky pest controls are chosen first, including highly targeted chemicals, such as pheromones to disrupt pest mating, or mechanical control, such as trapping or weeding. If further monitoring, identifications and action thresholds indicate that less risky controls are not working, then additional pest control methods would be employed, such as targeted spraying of pesticides. Broadcast spraying of non-specific pesticides is a last resort.
Some insect pests are not treatable with contact pesticide during certain stages of their lives when they form a protective barrier, such as bagworms and armored scale. Any pesticide used during those stages is wasted.
Alternatively, with herbicides, some herbicides are best used during certain stages of their life. For example, herbicides are most effective on Japanese Knotweed and Phragmites in the fall when the plants are actively transporting energy into their root systems and the herbicide can be moved faster.
Tips for using pesticides
- Select the least toxic pesticide appropriate; consider natural or biological controls before synthetic controls
- Use the most selective or targeted pesticide available
- Read and follow all label directions
- Wear appropriate clothing (at minimum long pants, closed toe shoes, gloves)
- Consider nearby water sources and only use pesticides that are approved for use near water
- Apply pesticides when weather conditions are favorable (i.e.: low wind, dry, appropriate temperature, or as label directs- some may recommend application when overcast or before precipitation.)
- Apply at the lowest functional rate; do not assume that more product is more effective; a pest can’t be more dead
- Wash exposed skin and clothing when finished making applications
- Store remaining pesticide in the original container with original label and at the appropriate temperature; if pesticide has been moved to a new container, mark accordingly, including the signal word on the label
- Clean all containers using the triple-rinse method prior to adding a new pesticide to the container; residual water should be used on appropriate pests
Besides the target pest, pesticides may have an impact on humans, pets, water quality, soil quality, air quality, or non-target organisms, including beneficial soil organisms. The non-target impact the pesticide has varies among pesticides and concentrations applied.
Pesticides range in toxicity which is noted on their labels. The signal words caution, warning, and danger or danger/poison indicate increasingly toxic substances. Pesticides without a signal word are considered very low toxicity.
Additionally, the amount of time a pesticide remains in the environment before it degrades is referred to as “persistence”. Persistence is not necessarily good or bad, but should be considered when working in the area after application. Persistence may affect non-target organisms too, although, some may not.
Although not required for homeowners, any one who applies pesticides for a fee is required to be a certified pesticide applicator. Certified pesticide applicators must take extensive tests and earn continuing education credits to retain their license. At this time GreenWeaver Landscapes employees four certified pesticide applicators and two registered technicians. We encourage all employees to earn this certification whether they will use pesticides or not because the knowledge learned from studying is so valuable.
So you now see that best practices for using pesticides in the landscape require intelligent consideration of not only what the pest is, but why the pest exists and how it is problematic. If next time you notice a weed or insect in your landscape that doesn’t seem right, do a little research about it first and then follow the steps to IPM before reaching for a pesticide.