Objectives
- To assess the tolerance of flax to potential new herbicides that could improve wild oat and/or cleavers management in flax crops.
- To determine the effects on flax production of stacking multiple agronomic factors together to develop best management practices for high-yield flax production.
- To determine the effects of including winter annual crops, perennial crops, and silage crops on integrated weed management in flax over the long term.
Project Description
Improving weed management in flax is critical to improving the overall value and adoptability of this crop in Western Canada. This project was carried out with the objectives of discovering short-term (herbicides, fertilizer, fungicide and cultural practices) and long-term (cropping systems) on yield and weed management. After completion of the project (three experiments), following results were identified. For the short-term approaches, experiment 1 found that herbicides fluthiacet-methyl, pyroxasulfone, and topramezone all have the potentials to be utilized in flax production for both PRE and POST weed control. From experiment 2, it was identified that by combining higher seeding rates with narrow row spacing, 1.3X nitrogen fertilizer, and using a fungicide, flax yield was increased by 26% (313 kg ha-1). Fungicide had the greatest impact on flax yield out of the four factors evaluated in this study. Under the long-term approach, experiment 3 identified that diversifying crop rotations with a three-year alfalfa crop found to be the most consistent and effective in controlling wild oat and cleavers in flax. Diversification with winter crops in the rotation showed some promise in managing weeds but depended on their winter survival. Crop diversification with silage was not effective in managing either weed. The least diverse rotation (with three flax crops in rotation within five years) was the most ineffective in managing weeds. Importantly, flax yield under alfalfa rotation was comparative or even greater than most other rotations allowing its adoption in cropping systems for better weed management. Overall, this project identified that diversifying herbicides, intensifying inputs (fertilizer, fungicide), optimum cultural strategies (narrow row spacing and high-density planting) and diversifying crop rotations can provide better weed management and increased crop yields in flax.
Grower Benefits
From the outcome of this project, we can recommend farmers to diversify the herbicides used in current flax cropping systems with fluthiacet-methyl, pyroxasulfone, and topramezone as both PRE and POST emergence herbicides either using as alone or tank-mixed with other registered herbicides in the market. Diversifying herbicides by using these new herbicides can be the best precaution to reduce the development of herbicide resistant weeds in flax.
At the same time, we recommend integrating 900 seeds m-2 planting density, 20-cm row spacing, 1.3X nitrogen fertilizer rate and application of fungicide (fluxapyroxad and pyraclostrobin) to increase flax yield. Finally, we recommend using a more diverse crop rotation strategy (particularly including a perennial forage crop) in order to manage wild oat and cleavers when it is becoming a problem. Overall, we recommend practicing all these three strategies (diversifying herbicides+ stacking agronomy + diversifying crop rotations) for sustainable flax crop production in the prairies.
