Septoria tritici update

The resistance of various wheat varieties to the Cougar race of Septoria tritici was raised by Lee Bennett during the variety plot tour at the open day.

Cougar, a highly resistant wheat variety in its day, has played an important role as a parent and is present in the background of many wheat varieties on the current Recommended List.

However, many of these varieties were infected more than expected by S tritici last season, leading the AHDB to put out an addition table of resistance scores for RL varieties, based on last season’s results, alongside the standard three-year table.

These tables clearly indicate that not all varieties have been equally affected, and some, including RAGT’s RL material, held up very well.

“There was a lot of noise last year about the Cougar race of S tritici,” said RAGT managing director Lee Bennett. “It wasn’t that new to us as it was first discovered in 2015 in Ireland.

“Last year varieties with Cougar in their background came under pressure, taking a bit more tritici than we would normally expect.

“However, the climatic conditions of 2021 were completely different to this season and Septoria per se has not presented the same levels of concern in any varieties.”

Three-way Cougar crosses fared better than straight Cougar crosses in 2021, including RAGT’s three RL newcomers, RGT Bairstow, RGT Stokes and RGT Rashid, which have continued to excel this season.

“As a business we continue to be impressed by how our three-way Cougar crosses are presenting themselves this year and they are carrying far less disease than many other varieties with any Cougar in their pedigree,” said Lee.

All have retained one-year S tritici resistance scores above 6 and strong three-year scores (see table). RGT Rashid, a new Group 3 wheat, has the highest S tritici rating of all RL soft wheats, just pipping RGT Stokes, which tops the Group 4 soft sector, with RGT Bairstow following a close second.

The trio created plenty of interest on the day. RGT Bairstow is one of the UK’s most consistent varieties, whether as a first or second wheat or on light or heavy soils, regardless of season or region.

It is a high-tillering variety with good autumn vigour, and is quick to get away in the spring. RGT Bairstow has a long grain-filling period that helps produce exceptional yields.

RGT Stokes is suitable for early drilling but can also be sown up to the end of January. The variety is recommended for the UK and excels in the north and west.

It has the highest alcohol yield of the 2021 set and is rated positive for distilling (SWRI report 2021).

RGT Rashid has the best and good resistance to rusts and fusarium. Relatively late to mature, it has good straw strength and can be pushed for yield.

It is the highest yielding Group 3 for the East and is well suited to southern regions and up the eastern side of England. It has performed well in RAGT early drilled (September) trials but can be sown to the end of January.

S tritici resistance scores


One-year score

Three-year score

RGT Bairstow



​RGT Stokes



RGT Rashid



Discover more about the resistance of various wheat varieties to the Cougar race of Septoria tritici and more here.

Source: AHDB RL 2022/23

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