Crop & Pest Report


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Waterhemp has Emerged in 2017 (5/18/17)

Waterhemp has emerged in Minnesota and North Dakota.

Waterhemp has Emerged in 2017

Waterhemp has emerged in Minnesota and North Dakota. First confirmed fields with waterhemp were near Willmar and Breckenridge, MN on May 9, 2017. Emergence date tracked closely with first confirmed sighting in fields in 2016.

Waterhemp is a member of the pigweed family including redroot pigweed and palmer amaranth. Distinguishing different pigweed species is challenging, especially in the seedling stage. Waterhemp cotyledons are more egg-shaped than the narrow, linear cotyledons of redroot pigweed. First true leaves are generally longer and more lanceolate than redroot pigweed (see image). Seedlings are free of hairs with leaves that are dark green with a waxy or glossy sheen.

Waterhemp is common in southern Minnesota and in western MN and eastern ND to the Canada border. Waterhemp thrives in wet areas of fields, but has adapted to a variety of conditions. Waterhemp germinates and emerges in mid-May and continues to emerge following precipitation well into August. We have seen evidence waterhemp will emerge following small grains harvest and produce viable seed if not properly managed.

There is great genetic diversity with waterhemp that has led to herbicide resistance including ALS inhibitors (SOA2), photosystem II inhibitors (SOA5), PPO inhibitors (SOA14), and glyphosate (SOA9).


Tom Peters

Extension Sugarbeet Agronomist

NDSU & U of MN

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