Why Intrepid has use restrictions and advice for complying

In some Michigan counties, growers need to know what wild plants grow in their area in order to use Intrepid insecticide.

Intrepid is an insecticide labeled for use in many fruit, vegetable and field crops in Michigan. Intrepid is an insect growth regulator and a reduced-risk product. This means it poses less of an environmental risk than broad spectrum insecticides. Intrepid is very effective against moth larvae. It must be ingested (eaten) to be effective. It causes the affected larvae to try and molt. This can be fatal if the caterpillar is not ready to molt.

The Intrepid label has an Endangered Species section that states that for users in Allegan, Monroe, Montcalm, Muskegon, Newaygo and Oceana counties, you must follow the “Endanger Species Protection Bulletin” for the county where you are applying Intrepid and for the month you are applying the material. With Intrepid, the Endangered Species Protection Bulletin is for the Karner Blue Butterfly. The Karner Blue is found around the Great Lakes in Indiana, Michigan, Minnesota, New York, Ohio and Wisconsin. The restriction states, “Do not apply this product within one mile of sandy habitats that support wild lupine plants.” Michigan State University Extension recommends that if you farm in these counties, you go to the Endangered Species Protection Bulletin website and print off the bulletin for your county for the month that you plan to apply Intrepid. You need to learn to identify wild lupine and the dry sandy areas where it grows. These bulletins are part of pesticide label and must be followed to legally apply Intrepid.

Wild lupine
A wild lupine in Idaho. Photo credit: Mark Longstroth, MSU Extension

When I share this with growers, many give me a puzzled look and ask, “What is a lupine?” They have never seen or heard of it before. Lupines are a large genus in the pea family with many species in North America. Lupines are distinct and easily recognized. They have distinct palmate leaves and the flowers are born on upright spikes. The flowers are easily recognized as pea flowers. Flower color is violet, blue or even pink or white and the fruit are short, fuzzy pea pods.

Lupinus perennis L. is the lupine that is native to Michigan. Michigan’s wild lupines are found primarily on dry, sandy soils in open or partially shaded habitats. Many of the areas where the lupine grows are oak savanna and pine or oak barrens. Lupines may also grow in power line right-of-ways, and other open areas that are maintained as early successional landscapes by suppressing the growth of shrubs and trees. Without natural or artificial disturbance, savanna and barrens communities develop into shrub or forest communities. In shaded habitat, lupines may survive, but with poor vigor and without flowering.

So why are we protecting a plant if we are worried about a butterfly? The Karner Blue butterfly larvae feed on the lupine and nothing else. Counties that do not have the restriction are counties where the lupine has not been found. If you do have sandy habitats that support wild lupine within one mile of your fields, you should choose another insect control option. Intrepid is the only product with this restriction, and the similar product Confirm has no such restrictions.

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