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Raise, Grow, Harvest, Eat, Repeat

A blog for growers, consumers, and backyard gardeners to grow, eat, and connect in the local food system.

Pest of the Week- Colorado Potato Beetle


To kick off Pest of the Week , let's talk about a pest that you may be seeing. This past week I visited a grower that while we were looking at their potato plants we came across juveniles of the Colorado Potato Beetle (CPB).

Source: NC State University

It's a reddish, cream striped beetle seen here in the provided photo that can do substantial defoliation if allowed for populations to increase. It feeds on leave tissue and in some cases can defoliate the whole plant. While you may not have yet seen it in your garden, you should also be looking for the eggs of this beetle (pictured below). They are orange and fairly easy to identify. The juveniles may also be present too. If you see either of these, you should go ahead and either a) remove them and destroy or b) be prepared for the adults.

Source: Purdue

So what then are some solutions for control of these pests? Your first step as with any integrated pest management plan (IPM) is to do a beetle count. Going out into the rows and counting the adults can give you an idea if you need to take any sort of action other than hand removal. This is what we call an insect threshold. If you reach a "Number of insects per number of plants", spray recommendations are in order if you so choose. An insect threshold may also be combined with defoliation of the plant (typically a percent). For instance with CPB, a recommendation for spraying is when there are 25 adult CPB/50 plants or 10% defoliation. Easy enough, right? But you know yourself what you are capable of and you might have 20 plants with much more than 25 adults on them.

What I typically recommend is hand removal if you have a small potato planting. While walking down this grower's potato patch of about 50 plants in one row, I only found 3 juveniles. The adults are fairly easy to remove especially in the morning and then killed. For larger plantings, there are numerous pesticides on the market that are available for use including some for organic production (known as OMRI).

More information can be found at this handy guide from UMass (https://extension.umass.edu/vegetable/articles/managing-colorado-potato-beetle).

Grant



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