Growing Green: Proper Use of Garden Insecticides
The warm, humid days of summer have finally arrived, and with them come a variety of insects that threaten our gardens. Colorado potato beetles, aphids, leaf hoppers, cucumber beetles and numerous others are very active this time of year, and many home owners choose to use insecticides to rid themselves of these pests and the damage they wreak.
If you go out to your garden and discover an insect invasion, the first thing you need to do is identify the invader in question. There are many beneficial insects in Minnesota, and you don’t want to destroy these populations. (Beneficial insects are any of a number of species of insects that perform valued services like pollination and pest control.) Honey bees, lacewings, a variety of beetles, syrphid flies, spechid wasps and ambush bugs are all beneficial insects we want to keep in our gardens. To identify your garden pests, try out the “What Insect is this?” diagnostic tool at http://www.extension.umn.edu/gardeninfo/insectgallery.
If you have an insect pest, chose a product that states it is effective against that insect. Also, consider the type of plant to which you will be applying the insecticide. If you are applying an insecticide to a food producing plant, make sure that the product states that it is safe to use on food crops. I can’t tell you how often I have had to disappoint a gardener who had selected the wrong chemical with the advice: “Don’t harvest and eat the veggies on the plants you have sprayed!” Read and understand all label instructions before purchasing the product. If you have questions, ask the specialist in your store, or call the Extension office before bringing the product home.
When using the product, follow application instructions precisely. MORE IS NOT BETTER! The directions are your contract with the producer that you will apply it correctly. Incorrect application of insecticides can kill the plants to which they are applied, or can make you ill. Be very careful in application and accurate in measuring and mixing chemicals. To be on the safe side, try ready-to-use chemicals instead of concentrates.Fortunately, you have many organic and synthetic choices available. Pesticides such as insecticidal soaps, Bt (Bacillus thuringiensis), NEEM, horticultural oils, pyrethrins and rotenone are all organically derived. This does not mean that they are not toxic to humans and wildlife. Read the label to familiarize yourself with the hazards of using any product you select, and the precautions you must take in their use.
For more in depth information, consult the Homeowner’s Guide to Integrated Pest Management (IPM) in Minnesota at the Minnesota Department of Agriculture website: http://www.mda.state.mn.us/plants/pestmanagement/ipm/homeipmguide.aspx
Robin Trott is a Horticulture Educator with University of Minnesota Extension.