Yard and garden products to treat insect and disease problems, simplified

In today's "Growing Together" column, Don Kinzler says if gardeners are familiar with a handful of products, they can treat most issues — and having everything on hand makes early treatment easy.

Home gardeners have many choices for controlling insects and diseases. David Samson / The Forum
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Do you know what you get when two peas fight? Black-eyed peas.

Even if vegetables can’t fight, there’s plenty of tension around the yard and garden from insects and diseases. Insects have been out in full force during this hot, dry year. In years with abundant moisture, diseases are even more prevalent.

When bugs chew holes in leaves, and blights threaten to take our plants under, most of us search for a remedy. Standing in the aisle at the garden center or hardware store can be confusing, as most shelves are lined with a multitude of products. Which to choose?

Luckily, if we’re familiar with a handful of products, they can be used to treat most insect and disease problems. Having several of the products on hand makes early treatment easy.

The following are products that will control most yard and garden insects and diseases.


Disease control

  • Most diseases around the yard and garden are caused by fungi. The most common active ingredient in disease-controlling fungicides is chlorothalonil, which can be found in fine print on the front of labels. Many products listed for vegetable, flower and fruit disease control contain the ingredient, and some combine it with an insecticide and package it as rose dust or fruit tree spray.
  • Copper, which is one of the oldest fungicide ingredients, is often used where an organic material is desired.
  • It’s important to note that fungicides are most effective as preventatives, and any of these products should be applied at the very earliest sign of disease to prevent the disease’s spread to healthy foliage. Always read and follow the label instructions.

Insect control

Holes caused by cabbage worms can be prevented with insecticides. David Samson / The Forum

  • Pyrethrin: One of the earliest insecticides, it’s derived from a species of chrysanthemum. Although it gives a quick knockdown of insects, pyrethrin breaks down rapidly, leaving little or no residual control. It's one of the most common organic insecticides.
  • Permethrin: Sold under brand names such as Eight, this synthetic insecticide is composed of the same chemical structure as pyrethrin, but it has a longer residual control. It's especially useful for vegetable gardens because it controls most major pests and has a short interval between application and safe harvest.
  • Carbaryl: This is the active ingredient in some products marketed as Sevin, although newer forms of Sevin contain synthetic pyrethrin. It's effective against many yard and garden insects.
  • Malathion: First introduced in the 1950s, it controls a wide spectrum of insects on a wide variety of plants. It's useful in a rotation on berry and fruit crops because the interval between application and safe harvest is only one to three days, depending on the crop.
  • Spinosad: A relatively new insecticide that is proving highly successful for control of many insects. It’s derived from a soil-dwelling bacterium that was first discovered near an abandoned rum distillery, and it's cleared for many organic uses. Because of the short interval between application and safe harvest, it’s a good choice for berry and fruit crops.
  • Bacillus thuringiensis: Abbreviated BT, these bacteria-based insecticides are an effective organic way to control caterpillars, such as the green worms that attack cabbage, broccoli and cauliflower. It must be applied when caterpillars are young, as it has little effect on older insects.
  • Insecticidal soap, neem oil, horticultural oil: Relatively safe to beneficial insects, these products can control soft-bodied pests like aphids, mealybugs, thrips, whiteflies, mites and scales. Because these products work when contacting the insects, an effective application must coat both the upper and lower leaf surfaces and stems. Repeat applications are often necessary.
  • When using any of the insecticides listed above, always read and follow the label instructions to determine the type of insects controlled and the proper rate and method of application.

Don Kinzler, a lifelong gardener, is the horticulturist with North Dakota State University Extension for Cass County. Readers can reach him at

Don Kinzler column mug.jpg
Don Kinzler, "Growing Together" and "Fielding Questions" columnist.

Don Kinzler, a lifelong gardener, is the horticulturist with North Dakota State University Extension for Cass County. Readers can reach him at
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