Weed suppression by alfalfa (Medicago sativa) in subsequent cereal crops: a comparative survey

P. D. Ominski, M. H. Entz and N. Kenkel

Abstract
A survey was conducted in Manitoba, Canada, in 1993 and 1994 to investigate weed populations in commercial cereal fields that had been preceded by either M. sativa [alfalfa] hay or cereal grain crops.

A total of 117 fields were surveyed; approximately half from each field type. Principle component analysis indicated that the inclusion of M. sativa in crop rotations resulted in weed communities different from those of continuous cereal fields.

Naturally occurring populations of Avena fatua, Cirsium arvense, Brassica kaber and Galium aparine were lower in cereal fields that had previously contained M. sativa than in cereal fields that had been preceded by a cereal crop. Lower field uniformity values for C. arvense and Avena fatua indicated that these weeds were also more patchy in the M. sativa rotations. Population differences between field types were non-significant for Amaranthus retroflexus, Chenopodium album and Polygonum convolvulus [Fallopia convolvulus], whereas populations of Taraxacum officinale and Thlaspi arvense were greater in M. sativa/cereal fields than in continuous cereal crops. No consistent effect of field type on Setaria viridis populations was observed.

These results show that M. sativa effectively suppressed some, but not all, of the weeds found in the study area. Including M. sativa hay crops in crop rotations can be part of an integrated weed management strategy for weeds such as A. fatua, B. kaber and C. arvense.


Source
Weed Science (1999) 47: 282-290


Author Locations and Affiliations
Department of Plant Science, University of Manitoba Winnipeg, Manitoba, R3T 2N2, Canada


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Posted September 2007