What is that? – Waterhemp

Posted: August 14, 2019

Why control weeds?

“Plants out of place” is a phrase often used to describe weeds. In farm fields, weeds steal nutrients, water, and sunlight from crops. This leads to poor crop yields, or less grain harvested per acre. Uncontrolled weeds may cause other problems, too:

  • Machinery damage during harvest
  • Contamination of harvested grain
  • Larger weed infestations in following years as the plants spread more seed

What is waterhemp?

Waterhemp is a major agricultural weed ranging from three to six feet tall. Seen from the edge of a field, waterhemp is a skinny, bristly, yellowish-green, and sometimes reddish-green plant. It is especially noticeable in soybean fields where it may be twice as tall as the crop.

Waterhemp grows quickly, blocking sunlight from crops. Rather than appearing just in spring or early summer like many other weeds, it continues to emerge (sprout from seed) throughout spring and summer. Even when removed by tillage or herbicide, more new waterhemp plants can keep sprouting.

Waterhemp seeds are round, dark brown, and a little bigger than a poppy seed. One waterhemp plant can produce anywhere from 250,000 to over 1 million seeds! All those seeds have another advantage: they can remain viable (able to sprout and grow) for at least a few years.

Adding to the challenges it presents to farmers, waterhemp evolves quickly. In some places, it is resistant to more than one herbicide (weed killer). Using mechanical tillage instead of herbicides isn’t practical in no-till fields or where the crops have grown too large to allow tillage equipment. If the weedy area is small enough, hand-pulling waterhemp may be the only way to control it.


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