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Paraquat for Managing Weeds in Alfalfa (Medicago sativa)

Published online by Cambridge University Press:  12 June 2017

Albert E. Smith
Albert E. Smith*
Affiliation:
Agron. Dep., Univ. Ga., Griffin, GA 30223-1797
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Abstract

Experiments were conducted over 2 yr and at two locations in Central Georgia to determine the influence of paraquat applied for weed control in the spring and following first harvest on alfalfa yield and crown carbohydrate content. Paraquat at 0.28 and 0.56 kg ai ha-1 controlled most annual cool-season weeds at 20 d after March treatment. These rates controlled annual warm-season weeds when applied as early as 7 d after first harvest. Treatments applied during March and as late as 7 d after first harvest did not influence alfalfa production or crown carbohydrate content. However, paraquat applied 14 d after first harvest reduced alfalfa yield 40% and significantly decreased crown carbohydrate content at second harvest but the alfalfa had fully recovered by the third harvest. This indicates that alfalfa is resilient to chemical defoliation by paraquat applied for weed control.

Keywords

Paraquat, 1,1′-dimethyl-4,4′bipyridinium ionalfalfa, Medicago sativa L. ‘Apollo’Chemical defoliationherbicide injuryhay productiontotal available carbohydrates
Type
Research
Information
Weed Technology , Volume 5 , Issue 1 , March 1991 , pp. 181 - 184
Copyright
Copyright © 1990 by the Weed Science Society of America 

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References

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