Identification

Glossy, long, hairless, narrow leaves and stems.The stem colours can range from green toredish/purplish. Waterhemp can grow to be5-8 feet tall.

Habitat

Habitat

Waterhemp is an aggressive annual broadleaf weed found in southernOntario and Western Quebec, typically in disturbed habitats such asditches, fields, etc. Its primary habitat is wet, low-lying areas but isalso well adapted to reduced and no-till situations.

Reproduction

Reproduction

A single female plant can produce anywhere from 35,000to 1,200,000 seeds. Waterhemp is dioecious, meaning themale and female flowers occur on separate plants. It onlyreproduces by seed, and once established, populations canspread as rapidly as other pigweeds. Seeds can remainviable in the soil for 4 years and can produce a strongseed bank.

Yield Loss

Yield Loss

In soybeans, waterhemp interference can result in yield losses of up to 73%.1 In corn, waterhemp interference can result in yield losses of up to 38%.2 The dioecious nature of waterhemp increases the diversity within populations,increasing the potential to spread resistance and other survival genes to subsequent generations.

subsequent generations

How to Outsmart Waterhemp

  • Scout early and often.
  • Control before it reaches 4 inches.
  • Start Clean with a residual herbicide PRE for extended control.
  • Always use two effective modes of action on the targetweeds to help reducde resistance selection pressure.
  • Stay Clean with a POST tank mixfor in-crop applications.

Sources:

1 Vyn, J.D., Swanton, C.J., Weaver, S.E., and Sikkema, P.H. 2006. Common waterhemp control in soybeans. Department of Plant Agriculture, University of Guelph, Ridgetown College; Department of Plant Agriculture, University of Guelph; Harrow Research Station, Agriculture and Agri-Food Canada.

2 Vyn, J.D., Swanton, C.J., Weaver, S.E., and Sikkema, P.H. 2006. Control of common waterhemp (Amaranthus tuberculatus var. rudis with pre and post-emergence herbicides in maize (Zea mays L.) Ridgetown College, University of Guelph; Department of Plant Agriculture, University of Guelph;Agriculture and Agri-Food Canada.