July 10, 2014
New Disease Surveillance Programme to Help Wheat Growers Across the Country
A new disease surveillance programme to help wheat growers across the country achieve the most cost-effective control of rusts and Septoria through the best-informed variety choice and fungicide use has been launched by research-led agronomy leader, Agrii this summer.
The Agrii National Cereal Disease Survey (ANCDS) complements and extends the UK Cereal Pathogen Virulence Survey (UKCPVS) and the HGCA Recommended List variety resistance ratings. It provides real-time seasonal disease development intelligence from untreated plots of key wheat varieties grown to the same protocol at a large number of locations from Aberdeen in the northeast to Truro in the south west.
Following piloting with 36 varieties across 14 sites in the current season, the survey is being extended and developed into an annual programme from this autumn to add to the company’s growing portfolio of decision-support tools.
“Recent experience reinforces just how rapidly variety disease resistance can be overcome by changes in a pathogen like yellow rust,” pointed out international wheat consultant, Bill Angus at the new programme’s launch. “What’s more, today’s very narrow genetic base arguably makes us more vulnerable to such changes than at any time since the disastrous Rothwell Perdix breakdown of 1967.
“Yes, we are growing a far wider range of varieties. But so many of them are so closely related that we are relying on perilously few yellow rust resistance genes. It only takes a quick glance at the pedigrees, for instance, to reveal that fully 58% of the Nabim Group 3 and Group 4 varieties on the current Recommended List have Robigus in their parentage.
Although inevitably historic and from a limited number of untreated sites, Bill Angus stressed that the RL disease resistance ratings from HGCA and diversification data from UKCPVS provide a vital information base for agronomists and growers.
With the extent of current genetic vulnerability and the scale as well as speed of recent pathogen change – not to mention ever-increasing pressures on agrochemical availability and efficacy – however, he is adamant that extra real-time disease development intelligence is essential these days.
That’s why he and consultant cereal pathologist and long-time UKCPVS project leader, Dr Rosemary Bayles have been working with the Agrii R&D team to establish and develop the new surveillance programme.
“It’s all about agronomic risk management,” explained Agrii northern R&D manager, Jim Carswell, setting out the programme. “Through ANCDS we will be providing our agronomists and growers with the most up-to-date in-season intelligence on the development of yellow and brown rust and Septoria tritici from their areas in the wheats they are growing.
“Information from our 14-plus disease tussock sites across the UK will provide an early warning system, enabling growers to keep ahead of disease development with the best possible fungicide programme planning and management. It will also ensure they have the very latest information on the resistance status of varieties they may be considering growing to inform their decision-making ahead of autumn planting.
“Yellow rust was something we didn’t really see in the north not so long ago,” he reported. “At the end of January this year, though, 68% of varieties in our Bishop Burton Technology Centre plots were showing infection. We’ve been recording big differences in infection levels between varieties in our Perth and Aberdeen plots too; and yellow rust is also becoming more evident at our south western sites. In just the same way, we’re seeing noticeably greater Septoria development in the eastern counties.
“Our regional network of monitoring plots will pick-up all these trends. By including a broad range of benchmark varieties with known sources of resistance we’ll also be monitoring changes in pathogen populations. In addition, virulence phenotyping by UKCPVS and genotyping at the Genome Analysis Centre will provide us with extra information on the genetic relationships between rust races.”
“These additional analyses will be particularly valuable in monitoring and predicting all-important pathogen changes,” said Rosemary Bayles. “Today’s yellow rust races are so much more virulent than those of the past. While the races of the 1970s were capable of overcoming three or four variety resistance factors, the Warrior race is virulent against 10.
“While genotyping clearly shows the Warrior race is quite different from previous UK races and originates from outside Europe as well as being more widely virulent, we have no evidence it is more aggressive than its predecessors in the UK, nor that it has a different life cycle with a sexual stage.
“Thankfully, the Warrior race has no virulence against some important current sources of resistance in our wheat varieties. However, we know it has several variants. So it’s only a matter of time before a variety that currently appears highly resistant to yellow rust ceases to be so. The fact that this breakdown could be very rapid indeed makes detailed monitoring essential if we are to avoid another Rothwell Perdix.
“The greater understanding we aim to gain of the very different ways in which susceptible varieties with similar breeding react to rust infection should also be invaluable in better informing agronomic planning as well as plant breeding.”