With oilseed rape prices up at £820/tonne in late April, it’s crucial to keep the plant as healthy as possible to reach its full yield potential, which includes the health of the stem.

Stem health is an area that is often overlooked and can have a serious impact on gross output. The stem-based diseases of Light Leaf Spot (LLS), Phoma and Verticillium Stem Stripe, can all have a serious impact on oilseed rape yields and oil quality. A flat crop is of no use to anyone.

Phoma

LLS is one of the biggest disease threats to the UK OSR crop. Previously considered a disease of the north, milder winter weather causing mutations and a reduction in azole efficacy, means LLS is spreading across the UK.

Phoma has become less of a problem with the use of resistant varieties and verticillium stem stripe is a more sporadic disease, closely linked to region, weather and crop factors.

Cylindrosporium is the stem-based stage of LLS, a disease caused by the pathogen Pyrenopeziza brassicae. LLS is a polycyclic disease, producing more than one infection cycle per season, and Cylindrosporium concentricum is its asexual stage.

Light Leaf Spot

However, the AHDB Recommended List offers good LLS disease resistance ratings based on the scoring of leaves, not on the stem. This means varieties with similar LLS scores on the AHDB RL, in reality have very different stem health scores.

Stem health is a key focus for the Limagrain European Breeding Programme, that selects plants with good strong stems that stand well.

All of the varieties currently on the RL have been scored for Cylindrosporium in our own trials, as well as for LLS in the RL Programme.

In 2020, we evaluated the stem health of several varieties that held the same LLS score of 7 on the AHDB RL (1= clean, through to 9 which was fully diseased.)

Aurelia scored an excellent 2 for overall stem health, Ambassador and LG Aviron scored a very good 3, but one competitor variety only scored a 6 despite also holding an LLS rating of 7.

Stem Canker     

The important message is to look behind the headline scores and
don’t assume that a good overall LLS score translates into a good stem health score.

Now in its 7th generation of bringing trait loaded hybrids to the marketplace, the Limagrain Breeding Programme has made ‘stem health’ a key focus.
The next generation of Limagrain lines are looking really clean for all the major stem-based diseases. These will begin to appear on the UK market this autumn, and will be more widely available in 2023.   

Limagrain Establishment Survey

To help mitigate the financial impact of an oilseed rape crop failing to establish, in 2021 Limagrain set up an Establishment Scheme with partners in the seed trade, says William Charlton, Arable Marketing Manager.

This provided an extremely useful insight into when crops are drilled, which we have tracked against weather at the time.

The scheme accounted for 19,000 ha of OSR planted in 2021, representing 8.3% of the total hybrid area and 6.2% of the total certified area.

The data showed:

• Where drilling was carried out in dry conditions, subsequent crop loss was closely correlated.
• Where there was rainfall on or around the two weeks from drilling, plant survival was much more likely.
• This reinforces the need for moisture for successful establishment of oilseed rape, to allow the crop to germinate and grow up and away from CSFB.
• Drill for conditions, not calendar date and choose a variety with adaptability that can cope with this.

Vigorous hybrids such as LG Aviron, LG Antigua, Ambassador or Aurelia, give growers the flexibility to wait for the right conditions.