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Serving: IN

Meet the Weed Enemies Here, Not In Your Fields

Meet the Weed Enemies Here, Not In Your Fields
Palmer amaranth is already here in various parts of Indiana; it's time to learn how to identify it.

If you're a farmer and you believe in the old adage, "Wait for a battle worth fighting for and a hill worth dying on," this might be it. Palmer amaranth is not your normal weed. If it gets a good foothold in your field, those who have battled it say you'll feel like David from The Bible going up against Goliath.

One way to avoid having to face Palmer amaranth on a "hill" in your field is to learn to identify it, and work out a management plan to stop it from getting a foothold.

Long petiole: Note the long, slender extension, called a petiole, on this leaf. You find it on Palmer amaranth, but not waterhemp.

Identification is important, notes Bill Johnson, a Purdue University weed control Extension specialist, because it is similar in appearance to tall waterhemp and both redroot and smooth pigweed, the species of the amaranth family that have been in Indiana fields for a long time, and that are typically controlled with normal herbicide programs.

Controls for waterhemp and Palmer are similar, but Palmer grows much faster and if it reaches the seed reproduction stage, can produce more seeds than other species in this family.

When the plant is small, Palmer amaranth forms a rosette shape when viewed from above. It almost resembles a poinsettia rosette formation. Waterhemp when viewed from above doesn't have the rosette appearance to the same degree.

Related: How to Identify Palmer Amaranth

The best way to identify Palmer from the other species is that it has a long petiole. This is the distance between the leaf and the main stem. Normally, you can double back the petiole and it will reach the tip of the leaf blade. You can't do that with waterhemp or redroot pigweed.

There are other methods but they're not as useful because not every Palmer plant has that characteristic. When some do and some don't it becomes more difficult to know for sure which species it is.

Plan on identifying them while they're young, Johnson says. Once the plants are four inches tall, there are very few options for stopping them post-emergence. The key is to use residual herbicides with burndowns and stop them early.

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