Weed Control Comparisons in Spring Wheat and Barley Under Organic and Conventional Management

Hans G. Nass and Jerry A. Ivany

The main strategy for weed control in organic systems is maintaining a balance between the crop and the weed species. Cultural methods, proper crop nutrition, crop rotation, intercropping, and the use of cover crops or mulches are considered the most effective methods for keeping weed numbers below threshold levels. However, even with the most effective prevention strategies there will still be weed problems to deal with, and weed control remains one of the major challenges facing organic crop producers. Chemical control is not an option for certified organic crop production, and farmers must rely on other strategies for controlling weeds when numbers exceed acceptable levels. Mechanical weeding using a finger weeder (tined harrow) may offer organic farmers adequate control and reduce problems with weeds in organic cereal production. However, there is limited information on the most effective strategies for using a finger weeder in cereals.

To provide more information on the effectiveness of finger weeding as a weed control strategy, researchers at the AAFC Crops and Livestock Research Centre in Charlottetown have established a two-year trial at the Harrington Research Farm, PEI. The trial will compare four weed control methods:

1) Finger weeding once, 5-7 days after seeding;
2) Finger weeding twice, at seeding and again 15 days after seeding;
3) Herbicide (Refine-Extra + MCPA); and
4) No weed control.

The weed control methods will be evaluated on four varieties of barley (Chapais, AC Westech, AC Queens, and Belmore) and four varieties of spring wheat (AC Walton, Belvedere, Glenlea, and AC Helena). The criteria for evaluating the effectiveness of the weeding strategies are weed number, weed biomass (weight), and the performance of the spring wheat and barley varieties.

The trial was established in 2002, and data on weed biomass and weed number, as well as on grain yield, have been collected for the initial year. So far the results suggest that finger weeding twice reduced the number and biomass of all weeds much more than finger weeding only once. However, the timing of the second finger weeding may need to be altered to cater to species differences in barley versus spring wheat. Preliminary results indicate that finger weeding barley two times had a negative effect on grain yield, as compared to finger weeding only once. In contrast, finger weeding spring wheat two times had a positive effect on grain yields, which were close those of wheat treated with herbicide. One barley variety (AC Westech) was particularly sensitive to finger weeding, and grain yields for this variety were less with finger weeding than with no weed control at all.


Related Links:
Further information on mechanical and flame weeding strategies for organic systems can be found at:

Mechanical Weed Control in Organic Systems
Av Singh, Organic Agriculture Centre of Canada


Researchers:
Hans G. Nass and Jerry A. Ivany
Crops and Livestock Research Centre
Agriculture and Agri-Food Canada,
440 University Ave,
Charlottetown, PEI, C1A 4N6
E-mail Contact: nassh@agr.gc.ca


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