Encyclopedia
Ramularia leaf spot (RLS), caused by the fungus Ramularia collo-cygni, has recently become widespread in Europe. Succinate dehydrogenase inhibitor (SDHI) and demethylation inhibitor (DMI) fungicides are mainly applied for disease control on barley fields, but pathogen isolates with a reduced sensitivity can cause difficulties. There is an urgent need for new spring barley cultivars that are more resistant to RLS development and can inhibit R. collo-cygni epidemics.
- Ramularia leaf spot
- fungicide target proteins
- CYP51
- azoles
- SDHI
- mlo gene
Barley (Hordeum vulgare L.) is one of the most important cereal crops grown in temperate regions worldwide [1]. Among the various pests and diseases that threaten sustainable barley cultivation [2], Ramularia leaf spot (RLS)—caused by an ascomycete, Ramularia collo-cygni—has become a new threat to barley cultivation. The first reported case of the disease dates back to 1893 in northern Italy and was identified by a notable botanist, Fridiano Cavara. For a century, RLS was a minor disease and did not cause any serious problems in barley cultivation, but the majority of R. collo-cygni outbreaks have been reported in the last few decades. The first official records in Germany, the UK, Ireland, and New Zealand are from the 1990s. In Finland, Sweden, Denmark, and France, the first records are from the 2000s, and in Estonia, Spain, and Australia, the first records are after 2010 [3]. Since the beginning of 2000, RLS has been considered to be an emerging disease of barley in Europe, South America, and New Zealand [2][4][5]. It is possible that RLS can lead to moderate barley yield losses of 5–20% or greater. Although the trigger of these increasing RLS epidemics is still under debate, R. collo-cygni adaptation to widely distributed RLS-susceptible barley cultivars and fungicides along with heat stress under global climate change will lead to a risk of future RLS epidemics [3][6].
References
- Newton, A.C.; Flavell, A.J.; George, T.; Leat, P.; Mullholland, B.; Ramsay, L.; Revoredo-Giha, C.; Russell, J.; Steffenson, B.J.; Swanston, J.S.; et al. Crops that feed the world 4. Barley: A resilient crop? Strengths and weaknesses in the context of food security. Food Secur. 2011, 3, 141–178.
- Walters, D.R.; Havis, N.D.; Oxley, S.J. Ramularia collo-cygni: The biology of an emerging pathogen of barley. FEMS Microbiol. Lett. 2008, 279, 1–7.
- Dussart, F.; Creissen, H.E.; Havis, N.D. Ramularia collo-cygni—An Enemy in Waiting. In eLS; 2020; pp. 1–8. Available online: https://pure.sruc.ac.uk/en/publications/riamularia-collo-cygnii-an-enemy-in-waiting (accessed on 13 October 2021).
- Havis, N.; Brown, J.K.M.; Clemente, G.; Frei, P.; Jedryczka, M.; Kaczmarek, J.; Kaczmarek, M.; Matusinsky, P.; McGrann, G.; Pereyra, S.; et al. Ramularia collo-cygni—An Emerging Pathogen of Barley Crops. Phytopathology 2015, 105, 895–904.
- McGrann, G.D.; Havis, N. Ramularia Leaf Spot: A Newly Important Threat to Barley Production. Outlooks Pest Manag. 2017, 28, 65–69.
- West, J.S.; Townsend, J.A.; Stevens, M.; Fitt, B.D.L. Comparative biology of different plant pathogens to estimate effects of climate change on crop diseases in Europe. Eur. J. Plant Pathol. 2012, 133, 315–331.
