Know What’s Bugging You (or your plants, more specifically)

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Posted on August 20, 2010 by rhallberg

Integrated pest management involves using the right control for the right pest at the right time. A can of Raid intended for ants will not generally be useful against a colony of wasps. Control of insects, weeds and diseases requires knowing what the problem is before reaching for the nearest pesticide.

So why can’t you just buy a general insecticide or herbicide and just spray it on the insect that’s eating your roses or the weed that’s taken over your garden? Imagine going to the hardware store and buying a general insecticide that costs $20. You bring it home and spray it on the insects that are on your roses (whatever they are). This gives rise to a few scenarios:

The insects slow down a little but in a few days there are actually more of them on the plant than there were before you sprayed. What happened? It’s possible that the insecticide was meant for another insect, or the insect was hiding in a covering that allowed it to protect itself from the spray until it was safe to start eating the plant again.
The insects died, but a few days later you notice hundreds of different insects on the plant, with holes in the leaves or several leaves missing. What happened? You may have killed a beneficial insect that was keeping this other insect away from your plant, but since the beneficial insect is now gone, the pest insect has free reign on your plant.

In both of these cases, we are assuming that you have read the label on the pesticide and that the pesticide can legally be used on roses.

In my garden, I ask myself many questions when I see what I think is a pest. Is that a good bug or a bad bug? Is there anything I can do to get rid of this bug other than apply a pesticide? Is that weed going to be a problem, and should I pull it immediately now that it’s young, or can I let it go for a few days until the weekend is here?

Being able to identify weeds can also help you avoid some serious rashes if you’re pulling weeds. Knowing that you’re about to touch a bunch of poison ivy will help you avoid a bath in calamine lotion later.

Understanding what disease symptoms look like can help you decide whether to use an insecticide or a fungicide. In some cases, insects can do damage that will turn leaves brown—making it look like you have a disease when you don’t. In other cases, some diseases look like an insect has poked holes in the leaves, leading you to purchase an insecticide that will do nothing more than waste your money (unless you can use it somewhere else in your yard on something that it will kill).

But how do you know what insect or disease you need to treat? Or figure out what weed is appearing in your vegetable garden? Below we have provided a very short (with an emphasis on VERY) primer on some common insects, weeds and disease symptoms you may see in your yard. However, chances are that you will find an insect, weed or disease that is not in this list. Don’t fret, because every state has dozens of people that can help you—in your state Extension program. If you own a small farm, call your state Extension agency. If you are a homeowner, call your state Extension Master Gardeners program. If you work in a school system, go to www.sripmc.org/schoolipm and find a person on our Members list.

Simple Identification Primer: Insects, Diseases, and Weeds

Insects