Objectives
The objective of this project was to demonstrate the response of flax to fungicide at varying row spacing levels and to better understand the sensitivity of flax to wider row spacing.
Project Description
Focusing on fungicides, the results from this project are consistent with previous research showing substantial benefits to spraying when pasmo pressure is sufficiently high but no benefits in the absence of disease. For this reason, careful scouting and monitoring of weather conditions is recommended to get the maximum benefit out of fungicide applications on a year-to-year basis. This disease moves progressively up the plant starting on the bottom leaves and the distinct banded stem lesions do not typically appear until relatively late in the season. Scouting should begin as soon the crop starts to flower and optimal fungicide application is normally about 7-10 days after the initiation of flowering. Later applications may be more beneficial if disease does not appear until relatively late during flowering. In the current project, fungicides only significantly increased yields in 1/3 years but the overall average yield increase of annual preventative applications (3-years) was 6%.
As for row spacing, flax appears to be quite sensitive to increasing row spacing when compared to other crops such as oats, wheat, canola and soybeans. Apart from 2014 where overall densities were lower and there was no effect of row spacing, flax populations declined as row spacing was increased. That said, the minimum recommended threshold of 300 plants/m2 was achieved with normal seeding rates in all cases, even 2014 at 61 cm row spacing. In 2015-16, plant densities declined by 37% when row spacing was increased from 25 cm to 61 cm. This suggests that the potential for higher morality should potentially be taken into consideration when seeding flax at wider row spacing. Yields also declined linearly with increasing row spacing and the results were remarkably consistent across years, despite the wide range of overall flax yield potential. The observed yield loss was 28% from 25 cm (10”) spacing to 61 cm (24”) spacing, or 2% for every 2.5 cm (1”) increase in row spacing. While the observed yield loss may be partly attributable to reduced competitiveness with weeds, even where weed pressure was relatively low, full canopy closure was still not achieved with wider row spacing, even at maturity (Fig. 1-5, Appendices). While these results do not by any means suggest that growing flax at row spacing wider than 25 cm is not a viable option for producers, they clearly show that this crop is better-suited to narrower rows and yield losses can be expected as row spacing is increased. Notably, there were no agronomically important interactions between foliar fungicide applications and row spacing for flax. Despite the hypothesis that wider row spacing may result in a more open canopy and subsequently less disease and potential benefit to fungicides, there was no evidence of this actually occurring. Yield increases with fungicide (or the lack thereof) were consistent across row spacing levels on average and within individual years. Similarly, the observed row spacing effects were consistent regardless of whether fungicide was applied
