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For the second year in a row, growers across the country have found hybrid oilseed rape better at dealing with the cabbage stem flea beetle challenge than conventionally-bred varieties.

Despite noticeably lower pressures from the pest and better moisture conditions at establishment last autumn, the nearly 200 growers involved in the second national CSFB management study conducted Bayer with ADAS and NIAB reported both noticeably lower levels of larvae and better larval recovery from hybrid varieties (Figure 1).

Figure 1: Crop Success by Variety Type (2020/21)


Crop Establishment (0= crop lost: 10 = perfect establishment)
Larval Level (0= no larvae or scar: 10 = more than 30 larvae/plant or multiple scars on all petioles & stems)
Larval Recovery (0=crop written off: 10 = no impact on normal crop growth & development)

Source: Bayer National CSFB Management Study 2021

This underlines the findings of the inaugural national study in the much more challenging 2019/20 establishment season.

Interestingly, like the previous year, there was not much to choose between hybrids and conventional varieties in immediate establishment terms. And, as one might expect, all three indicators of success – establishment, larval level and larval recovery – showed a clear improvement on autumn 2019.  Once again, though, hybrids proved better able to deal with CSFB larvae – both in limiting their apparent level and in recovering from any damage.

“Successful establishment is much more about having sufficient moisture at drilling and preserving it through the most vulnerable cotyledon stage until rooting is well enough developed than it is about breeding or, indeed, seed size,” points out Dekalb OSR breeder, Matthew Clarke.

“Our trials and field experience suggest the main cabbage stem flea beetle management value of hybrids lies in their superior ability to grow away from the pest.  But we also know that hybrids vary quite widely in their ability to do this, depending on their particular growth habit.

“Those with a relatively fast speed of autumn development are better able to make-up for any early leaf damage ahead of winter. We’ve also found hybrids that take-off earlier or more rapidly in the spring better at compensating for larval damage. In both cases, we’ve seen noticeably lower levels of main raceme loss and plant stunting from varieties with these traits.

“The all-round reliability we have long concentrated on building into our hybrids by breeding for key yield-protecting traits followed by selection in completed untreated plots under high stress situations is, we believe, an essential element in the integrated management of CSFB and other pests.”

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