Five years of OSR grower benchmarking confirms hybrid value

Hybrid varieties have stood out as noticeably more resilient in five years of national crop benchmarking with 900 growers across the country responsible for over 93,000ha of winter oilseed rape, with the most robust hybrids having a useful edge. The Dekalb studies run by Bayer each April since 2020 show an average 80% of plantings have been considered worth taking through to harvest by growers. This has ranged from 72% with conventional pure line varieties to 84% with comparable mainstream ‘double low’ hybrids.

This rises to 85% with Ex hybrids which have long had a reputation for robustness against 83% for other mainstream double low hybrids (Figure 1).

Figure 1: Average Crop Success by Variety Type

Source: Dekalb National OSR Benchmarking Studies 2020 - 2024; Bayer, June 2024

Further analysis suggests the resilience advantage of hybrids, in general, and Dekalb Ex hybrids, in particular, is associated with both better establishment and noticeably lower levels of CSFB larvae in the spring. “The differences in resilience between varieties have been most marked where crops have suffered the greatest challenges from CSFB,” notes Bayer national account seed manager, Sarah Bebb. “In these cases, growers have reported markedly lower larval scores in hybrid crops. At the same time, much higher proportions of hybrid plantings have been taken to harvest where larval levels are high (Figure 2).

Figure 2: Average Crop Success by Larval Score

Source: Dekalb National OSR Benchmarking Studies 2022 -2024; Bayer, June 2024

“It’s impossible to say whether the lower larval levels growers have seen in hybrid varieties is a real effect or more related to their better spring branching, crop development or compensation abilities,” she adds.

“However, the superior compensation abilities of hybrid varieties is crystal clear when we assess crop success at different larval levels. The proportion of hybrid plantings taken to harvest over the years is higher than pure lines at almost every level of CSFB larval pressure. But the gap between the two variety types really widens as larval levels go beyond 6 or 7 on the 0-10 scale.

“Our 2024 study reveals the average establishment score of this season’s crop is actually lower than the last really bad cabbage stem flea beetle season of 2019/20,” observes Sarah Bebb. “Interestingly, however, the proportion of plantings taken to harvest this season is well above that year.

“Better crop growth and development in the milder, wetter winter may have something to do with this, together with the notably lower levels of flea beetle larvae reported by growers. In both respects, this could well reflect the much wider use of hybrids – almost 60% of all main ‘double low’ varieties compared to less than 40% in 2019/20.”