Autotoxicity in Alfalfa
An autotoxic chemical is a “self-poison.” Alfalfa autotoxicity occurs due to the production of a chemical by the alfalfa plant that is toxic to alfalfa seeds and seedlings grown in close proximity to established alfalfa. Autotoxicity may have developed in alfalfa as a way to decrease resource competition.
Roots of alfalfa planted two weeks after a previous alfalfa crop was tilled (left) compared to roots of alfalfa planted 18 months after a previous alfalfa crop was tilled (right). Note lack of taproot on the leftmost roots.
John Jennings
Alfalfa planted two weeks after a previous alfalfa crop was tilled showing the impacts of autotoxicity (left) compared to alfalfa planted 18 months after a previous crop was tilled (right).
John Jennings
Do not plant alfalfa immediately after another alfalfa crop as growth inhibiting toxins may still be present in the soil from the former plants. Interseeding new alfalfa seeds into an established stand should also be avoided.
Prepared by the Alfalfa Pest Management Working Group.
Roots of alfalfa planted two weeks after a previous alfalfa crop was tilled (left) compared to roots of alfalfa planted 18 months after a previous alfalfa crop was tilled (right). Note lack of taproot on the leftmost roots. John Jennings.
Alfalfa planted two weeks after a previous alfalfa crop was tilled showing the impacts of autotoxicity (left) compared to alfalfa planted 18 months after a previous crop was tilled (right). John Jennings.
Gallery images courtesy John Jennings.
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