Extension

Courtney DeKalb-Myers, Assistant Extension Specialist in Consumer Horticulture

Late summer can be a difficult time for gardeners. Not only has persistent heat worn down the garden, insects and weeds have settled in and taken up what feels like a permanent residency. There is a lot of information online on how to handle these problems, including how to create homemade pesticides. The recipes are usually straightforward and consist of familiar household products, like dish soap, vinegar, salt, boric acid, and vegetable oil. It can be tempting to give these recipes a try when their ingredients are so readily available. However, their safety and effectiveness are not confirmed.

Most pesticide products purchased from box stores or garden centers are registered by the EPA. These products have undergone evaluation for their intended uses and come with a pesticide label that provides specific directions for application. This can include when to apply, what it can be applied to, what protective equipment might be needed, the appropriate weather conditions for application, post-harvest intervals, storage, disposal, and many other instructions on how to use the product with minimal risk to oneself and the environment. Home recipes do not come with a set of registered, verified instructions.

One common suggestion online is to use dish or antibacterial soap for insect control. Many of these products contain detergents, degreasers, fragrances, and other additives that can damage plant tissue. These products have also not been evaluated or labeled for use as pesticides. It is not recommended to use these products for insect control. A good alternative is to use insecticidal soap. While chemically similar to some dish soaps, these products are specifically designed to control insects and lower potential plant injury.

Homemade vinegar herbicides, mixed with dish soap and salt, circulate online as well. This mixture may kill contacted vegetation above the soil, but vinegar acts primarily as a contact herbicide and generally does not control the roots of established perennial weeds. Over time, salinity can build up and create a difficult environment for any plant growth, including desirable plants. It’s also important to note that household vinegar is usually around 5% acetic acid. Labeled herbicidal vinegar is available, but usually at a much higher concentration. Products containing higher concentrations of acetic acid can cause serious skin and eye injury, so it’s critical to read and follow the label directions. Wear the required personal protective equipment to prevent injury.

Before making the decision to apply a pesticide, it is critical to identify the pest and determine whether control is necessary. Some pest populations can be managed without treatment, and when treatment is necessary, choose a product labeled for the specific target pest and site. Gardeners who prefer organic approaches can look for OMRI (Organic Materials Review Institute) Listed products. When it comes to managing garden pests, familiar household ingredients are not necessarily safer. Careful label use goes a long way toward protecting gardeners, plants, and the environment.