1k. Discovery that Ramularia collo cygni causes leaf spotting in barley and development of a diagnostic to target fungicide use, saving the industry £5.4M per annum
Submitting InstitutionsUniversity of Edinburgh,
Unit of AssessmentAgriculture, Veterinary and Food Science
Summary Impact TypeEnvironmental
Research Subject Area(s)
Biological Sciences: Genetics, Plant Biology
Agricultural and Veterinary Sciences: Crop and Pasture Production
Summary of the impact
Impact: Economic: The first fungicide-based control schemes
minimising UK barley yield losses (saving approx. 516K tonnes / £95.1M per
annum). A risk assessment method, which minimised pesticide usage.
Significance: Barley is the second most popular cereal crop grown
in the UK — in 2012, 5.52 million tonnes of barley were grown (market
value £1.02 billion). The research led to savings to the UK farming
industry of ~£5.4 million per annum
Beneficiaries: Farmers, malting and brewing industries, UK tax
Attribution: Drs. Oxley, Havis, Hughes, Fountaine, and Burnett
(SRUC) identified the pathogen and produced a field test for early
identification of infestation.
Reach: Barley growing, malting and brewing sectors, seed and
agrochemical industries UK-wide and in Ireland.
In 1998 barley crops in the north of the UK suffered from an unknown
disease, which caused extensive premature leaf death and resulted in poor
yields and low quality. Although a similar problem had affected crops in
Germany and Ireland the previous year, there was little information on the
cause, the economic importance, or on methods to manage the problem. As
barley is the main cereal crop grown in Scotland, and the most valuable,
it was vital this new disease threat was managed.
- We began researching the disease in 1998 (the team included Drs. Oxley
(Senior Researcher, employed 1985-onwards), Havis (Researcher, employed
1996-onwards), Hughes (Researcher, employed 2003-2008), Fountaine (Plant
Microbial Ecologist, employed 2007-onwards), and Burnett (Team Leader,
employed 1992-onwards) identified the pathogen and produced a field test
for early identification of infestation), and initial work was funded by
the Home-Grown Cereals Authority (HGCA). This first project led to the
discovery that Ramularia collo-cygni (Rcc) was the main biotic
factor involved in leaf spotting in barley, causing a disease now called
Ramularia Leaf Spotting (RLS) [3.1].
- A subsequent three-year HGCA-funded project focused on the effect of
oxidative stress on the barley crop and the most effective chemical
control for RLS. It developed the first fungicide programmes aimed at
controlling RLS in barley crops.
- This initial research was followed by a three-year project, funded by
the Scottish Government (SG; 2000-3), which aimed to design a test that
would detect the fungus before symptoms appeared on the plant.
- The first diagnostic for the pathogen [3.2] was developed by the
research team and this nested PCR test was able to detect the fungus at
a molecular level. Field experiments showed that the test enabled the
detection of the fungus in the leaves two to four weeks before the crop
appeared to be affected. These findings demonstrated the importance of
applying fungicides to protect crops that had no visible disease
- Subsequent SG funded work (2005-2011) indicated that seed-borne
infection is the most important source of Rcc infection in crops. A new
PCR test developed and validated in our laboratories [3.3] indicated
widespread contamination of seed stocks throughout the UK.
- The fungus was found to be situated deep within seed tissue and
therefore not easily controlled by commercial seed treatments. Current
research projects are examining options for eliminating or reducing
pathogen inoculum in barley seed. Joint studies with the James Hutton
Institute, which involved genetic transformation of the fungus with
fluorescent tags [3.4], greatly aided study of the movement and
localisation of the pathogen in the plant.
- A joint PhD with John Innes Centre led to establishment of a reliable
method for inoculating plants with Rcc enabling experimental infection
studies. The same study showed that the appearance of Rcc was not
related to the introduction of lines resistant to the pathogen Blumeria
graminis f.sp. hordei [3.5]. This allowed breeders
to continue to use this genetic material in crossing studies aimed at
identifying resistance to RLS.
- Since 2007, joint research with HGCA has been directed towards control
of RLS through varietal resistance, seed health and forecasting.
- Our research showed that although most spore dispersal coincided with
leaf wetness late in the growing season, epidemic severity was strongly
correlated with sustained periods of leaf wetness earlier in the
development of the crop. This important discovery was used to produce a
- Testing of archive barley samples from Rothamsted Research revealed
that Rcc in barley crops in England increased greatly after 1998, while
resistance to a major group of fungicides, the strobilurins, could be
detected from 2001 onwards (3.5).
- The rapid appearance of resistance to this group of fungicides in Rcc
has led to new work in the area. Thus, two PhD students, funded by
agrochemical companies, are now examining the development of resistance
to fungicides and the method of reproduction of the fungus.
References to the research
3.1 Havis, N. D., Oxley, S. J. P., Piper, S. R. and Langrell, S. R. H.
(2006). Rapid nested PCR-based detection of Ramularia collo-cygni
direct from barley (Hordeum vulgare). FEMS Microbiology Letters.
256: 217-223. http://dx.doi.org/10.1111/j.1574-6968.2006.00121.x
3.2 Taylor, J. M. G., Paterson, L. and Havis, N. D. (2010). A
quantitative real-time PCR assay for the detection of Ramularia
collo-cygni from barley (Hordeum vulgare). Letters in Applied
Microbiology. 50: 493-499. http://dx.doi.org/10.1111/j.1472-765X.2010.02826.x
3.3 Thirugnana Sambandam, A., Wright, K. M., Havis, N. D. and Newton, A.
C. (2010). Agrobacterium-mediated transformation of regenerated
protoplasts of the barley pathogen Ramularia collo-cygni with
fluorescent marker tags. Plant Pathology. 60: 929-937. http://dx.doi.org/10.1111/j.1365-3059.2011.02440.x
3.4 Makepeace, J. C., Oxley, S. J. P., Havis, N. D., Hackett, R., Burke,
J. I. and Brown, J. K. M. (2007). Associations between fungal and abiotic
leaf spotting and the presence of mlo alleles in barley. Plant Pathology
56: 934-942. http://dx.doi.org/10.1111/j.1365-3059.2007.01680.x
3.5 Fountaine, J. M. and Fraaije, B. A. (2009). Development of QoI
resistant alleles in populations of Ramularia collo-cygni. The
second European Ramularia Workshop — A New Disease and challenge in barley
production. Aspects of Applied Biology. 92: 123-126. (Copy available on
Details of the impact
Impact on the Economy
Malting and brewing are very important to the UK economy with 1.65 million
tonnes and 53,000 tonnes of barley used for these purposes respectively in
2012. Premiums for grain of a quality suitable for malting can be valued
at an additional £5/tonne. Prior to 1998 RLS was not a significant disease
problem in the UK but now it is regarded as the second most destructive
foliar pathogen in the North and West of the UK. With a sudden, rapid
increase in the incidence of the disease in the country's barley crops,
especially in Scotland, there was an urgent need for information on the
disease and how to control it. The first HGCA-funded research quickly
provided growers with the first fungicide programmes aimed at controlling
RLS in barley crops, saving the industry an estimated £5.4 million per
annum from 2001 onwards.
Impact on Disease Control
The development of the first PCR diagnostic allowed the fungus to be
detected in leaves two to four weeks before symptoms appeared. This
enabled growers to target fungicide application, providing protection to
crops that had not yet developed visible disease symptoms. In Scotland the
area protected from Ramularia by an effective fungicide rose from 4,000 ha
to over 160,000 ha in just two years and more than trebled in the entire
UK to just over 350,000 ha. Identification of seed as a major inoculum
source enabled seed health schemes and treatments to be developed, aimed
at reducing or eliminating Rcc in barley seed stocks.
Impact on the Agricultural Industry
The increasing importance of RLS in spring and winter barley led to its
inclusion in the list of pathogens examined in HGCA-funded research into
Appropriate Fungicide Doses (2001-onwards). As a result, RLS is now
considered to be a major pathogen by the Chemical Regulation Directorate
and agrochemical companies must now screen for activity in new chemicals
used against the pathogen. Ongoing developments will have an impact on
reducing the current £57 million annual yield loss in UK barley
Subsequent HGCA-funded work allowed determination of resistance ratings
for Ramularia leaf spot in commercial UK barley varieties. Official
resistance ratings for Ramularia in spring barley varieties were published
for the first time in 2013. This is a significant step, as this
information, along with all project summaries, is sent out to 26,000
barley growers in the UK (over 3,000 of them in Scotland) and is used when
selecting the most appropriate varieties to grow. This reduces reliance on
pesticides and has environmental as well as economic benefits.
A forecasting scheme, based on leaf wetness at a key period in early crop
development was developed in 2010. The risk scheme allows farmers to
adjust fungicide programmes if they are located in a low or high-risk
region. The scheme has been publicised for 3 growing seasons via our Crop
Protection Report (http://www.sruc.ac.uk/info/120118/crop_clinic/500/crop_protection_report)
which received over 2,000 web page hits a month at the relevant publishing
dates, and through 600 Crop Protection Report subscriptions.
Providing practical information to the industry (farming, malting and
brewing, seed and agrochemical) has been an integral part of research
undertaken in the past 14 years. Our research findings are disseminated in
a number of ways; via press releases and articles, the SRUC website, SRUC
Crop Protection Reports and Advisory Newsletters, Open Days (approx. 250
attendees at each) and winter disease roadshows (approx. 200 attendees at
each) and farmer meetings (approx. 150 attendees at each). Feedback from
Open Days indicates that 95 to 100% of respondents are happy with the
findings presented and are confident it can make a positive impact on
their production systems. New scientific information has been disseminated
through peer reviewed papers and European and international scientific
conferences and workshops. We have promoted the research at two European
workshops organised specifically on RLS.
At the outset of this research, losses due to RLS in Scotland were
calculated to be £13M on an annual basis. Our research led to targeted and
effective fungicide programmes for growers offering major reductions in
yield losses due to RLS. By 2012, 98% of Scottish barley crops received
fungicides with the major products used highly active against RLS. The
pathogen decreases both yield and grain quality.
Sources to corroborate the impact
5.1) Professor James Brown, JIC. http://tinyurl.com/p4oy3rg
5.2) Dr Vicky Foster, HGCA (letter of support available on request). http://tinyurl.com/qfcjljk
5.3) Davies, D. H. K., Evans, E. A. and Oxley, S. J. P (2008). Changes in
pests weeds and disease in Scotland over the past 20 years Proceedings
Crop Protection in Northern Britain 2008. 12-22. http://tinyurl.com/pe5ynam
5.4) Pesticide usage survey-Arable crops SASA. This reference
corroborates the increase in fungicide usage described in the text. http://tinyurl.com/noy4xpn
5.5) Oxley, S. J. P., Havis, N. D., Sutherland, K. G. and Nuttall, M.
(2002). Development of a rationale to identify the causal of necrotic
lesions in spring barley and to identify control mechanisms. HGCA Project
Report No 282. http://tinyurl.com/nds4ag6
5.6) Oxley, S. J. P. and Hunter, A. E. (2005). Appropriate fungicide
doses on winter barley: producing dose-response data for a decision guide.
HGCA Project Report No. 366. http://tinyurl.com/n9gtew9
5.7) Oxley, S. J. P., Havis, N. D., Brown, J. K. M., Makepeace, J. C. and
Fountaine, J. (2008). Impact and interactions of Ramularia collo-cygni
and oxidative stress in barley (HGCA Project report 431 July 2008). http://tinyurl.com/pkptaym
5.8) Oxley, S. J. P. and Burnett, F. J. (2010). Barley Disease Control
Technical note TN611 ISBN 1 85482 867 3. http://tinyurl.com/ocx8kx4
5.9) Oxley, S. J. P. and Havis, N. D. (2010). Managing Ramularia
collo-cygni through varietal resistance, seed health and
forecasting. (HGCA Final Report 463 March 2010). http://tinyurl.com/pot5zla