Crops yields were not affected statistically significantly by fungicides. By extension, it means that under low levels of disease conditions, producers could avoid using fungicides without losing any yield potential while saving time, financial resources and the environment. For barely, daytime was the least effective application timing at all locations (Table 2). Dawn applications at Brooks were most effective (56% of the instances) for producing higher yields compared to the day and night times that both scored at 44%; Nighttime application was most effective at Lethbridge at (67% of the instances) compared to the day and dawn timings (scoring 50% each); Night applications also scored higher yields at Lacombe (83% of the instances) followed by the dawn time (67%) and day time (33%). Twinline was, in general, the most effective fungicide for barley (Table 2).
In case of wheat, no application timing seemed clearly effective, and there was lack of statistically significant differences in wheat yield for different treatments (Table 3). In general, the dawn time application was less effective than daytime or nighttime applications, both of which were equally effective. However, the differences were not statistically significant in terms of yield differences. For canola, daytime application was most frequently effective at Lethbridge and Brooks (78% and 67%, respectively) followed by the night and dawn times, respectively (daytime > nighttime > dawn time); Dawn time scored better at Falher in 56% of the instances compared to 44 and 33% for day and night times, respectively (Table 4). Quadris was, in general, the most effective fungicide for canola (Table 4).
In case of field peas, the dawn time and nighttime applications were more effective than day time applications. The trend of higher pea yield for dawn time and daytime applications was consistent across site-years; however, statistically significant differences in yield were observed only at the Falher site. The likely explanation of such diurnal trends of fungicide effectiveness may be that pea canopy structure and the diurnal folding of leaves in the absence of daylight allowed deeper fungicide penetration with increased fungicide residual activity within the bottom canopy. Priaxor was, in general, the most effective fungicide in case of peas (Table 5).
In general, our study results suggest that fungicides applied during the day, night or dawn time would be similarly effective on barley, wheat and canola, with some advantage of dawn or nighttime applications for peas. However, because of low disease pressure, the study could not maximize the differences between treatments.