To improve flax yield via improved agronomy and weed management by: i) assessing the tolerance of flax to potential new herbicides that could improve wild oats and/or cleavers management in flax crops, ii) to determine the effects on flax production of stacking mutiple agronomic factors together, iii) to determine the effects of including winter annual crops, perennial crops, and silage crops on integrated weed managment in flax over the long term
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 potential to be utilized in flax production for both PRE and POST weed control. From the experiment 2, it was identified that increasing the seeding rate from 450 to 900 seeds m2, reducing the row spacing from 40 to 20 cm and increasing the N rate to 130% did not have an individual impact on crop yields. However, when integrated, the two treatment combinations 900 plants m2-narrow row spacing-130% N-fungicide applied and 450 plants m2-narrow row spacing-130%N- fungicide applied increased yield by 26% (313 kg ha-1) compared to 900 plants m2-wide row spacing-65% N-no fingicde treatment. Fungicide application had the greatest impact on flax yield out of the four factors evaluated in this study. Under the long-term approach, the 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. This study was unable to identify any weed control benefit of having a silage crop in th e rotation compared to alfalfa rotation, but it was comparable to the least diverse rotation (three flax crops in rotation within five years) with full herbicide rates. Flax crop yields in the cropping systems study found to be considerably low due to poor growing conditions prevailed in 2019. Overall, this project identified that diversifying herbicides, intensifying inputs (fertilizer, fungicide), optimum cultural strategies (integrating cultural practices) and diversifying crop rotations can provide better weed management and increased crop yields in flax.
- Low yields (relative to other oilseed crops) and low weed control options due to the rise of herbicide-resistant weeds are the main constraints in the adoption of flax in the prairies.
- The three strategies identified in this project in order to address these issues were exploring the potential of new herbicides (diversifying herbicides) and diversifying crop rotations for the management of herbicide-resistant weeds, enhancing the crop yields by integrating best management practices (stacked agronomy).
- Herbicides currently not registered in flax such as fluthiacet-methyl, pyroxasulfone, and topramezone found to be effective in using as PRE and POST emergent herbicides as alone or as tank mixes with other standard herbicides.
- Moving from less diverse (frequently flax-based) crop rotations to more diverse (rotations with a perennial alfalfa crop) provided substantially greater wild oat (60-70%) and cleavers (50-60%) control compared to most other rotations without hampering crop yields.Increasing the seeding rate, reducing the row spacing and increasing the fertilizer rate had no individual effects on flax yields. The fungicide application is the predominant factor contributed to high yields in flax.
- The integrated approach of high seeding rates (900 seeds m-2), narrow row planting (20 cm), increased N fertilizer (1.3X) and using a fungicide Priaxor® 9 (fluxapyroxad and pyraclostrobin) increased crop yields by 26%.
- It is beneficial using all the above three strategies as possible in order to increase the sustainability of flax cropping systems. However, the potential new herbicides identified in this study needs to be registered in order to utilize them.