Can crop disease control cope with climate change?

Crop yields need to increase by at least 70% over the next 35 years in order to meet the global demands for food due to the increasing population and changing dietary preferences towards meat and dairy products in developing nations. Climate change threatens food security because pests and diseases that limit crop productivity are all sensitive to climate change and especially to more frequent extreme weather events. A more variable climate will mean greater uncertainty for crop yields because crop development stages, e.g. when reproductive organs such as flowers and seeds are produced, are especially vulnerable to short periods of extreme temperature or drought. For instance, Europe experienced an extreme climate event during the summer of 2003 when temperatures were ca. 6°C higher and rainfall was ca. 300 mm less than the long-term mean values. One impact of this summer was a record crop yield decrease of ca. 36% below average yield in Italy for maizePeer reviewedFinal Accepted Versio

Effects of root-infecting fungi on transport of metabolites in wheat

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Importance of Leptosphaeria biglobosa as a cause of phoma stem canker on winter oilseed rape in the UK

Phoma stem canker is a major disease of oilseed rape in the UK, leading to annual yield losses worth more than £100M. The disease is caused by two closely related species, Leptosphaeria maculans and L. biglobosa. L. maculans is generally considered more damaging, causing stem base canker; L. biglobosa is generally less damaging, causing upper stem lesions. Therefore, previous work has mainly focused on L. maculans and there has been little work on L. biglobosa. This work investigated the contribution of L. biglobosa to stem canker epidemics by assessing the amounts of DNA of L. maculans and L. biglobosa in upper stem lesions or stem base cankers on winter oilseed rape cultivars with different types of resistance against L. mac ulans. Diseased upper stem and stem base samples were collected from nine oilseed rape cultivars in a 2011/2012 field experiment at Rothamsted. The presence of L. maculans or L. biglobosa in each stem sample was detected by speciesspecific PCR. The abundance of L. maculans or L. biglobosa in each stem sample was measured by quantification of L. maculans DNA and L. biglobosa DNA using quantitative PCR (qPCR). The amounts of L. biglobosa DNA were greater than those of L. maculans DNA in both upper stem and stem base samples. These results suggest that the severe upper stem lesions and stem base cankers in the 2011/2012 cropping season were mainly caused by L. biglobosa, suggesting that L. biglobosa can sometimes cause considerable yield loss in the UK. There were differences between cultivars in the amounts of L. maculans DNA and L. biglobosa DNA, with the susceptible cultivar Drakkar having more L. maculans DNA than L. biglobosa DNA while resistant cultivars had less L. maculans DNA than L. biglobosa DNA. These results suggest that L. biglobosa can be an important cause of phoma stem canker on oilseed rape in the UK.Peer reviewedFinal Published versio

Identification, Molecular Characterization, and Biology of a Novel Quadrivirus Infecting the Phytopathogenic Fungus Leptosphaeria biglobosa.

Here we report the molecular characterisation of a novel dsRNA virus isolated from the filamentous, plant pathogenic fungus Leptosphaeria biglobosa and known to cause significant alterations to fungal pigmentation and growth and to result in hypervirulence, as illustrated by comparisons between virus-infected and-cured isogenic fungal strains. The virus forms isometric particles approximately 40–45 nm in diameter and has a quadripartite dsRNA genome structure with size ranges of 4.9 to 4 kbp, each possessing a single ORF. Sequence analysis of the putative proteins encoded by dsRNAs 1–4, termed P1–P4, respectively, revealed modest similarities to the amino acid sequences of equivalent proteins predicted from the nucleotide sequences of known and suspected members of the family Quadriviridae and for that reason the virus was nominated Leptosphaeria biglobosa quadrivirus-1 (LbQV-1). Sequence and phylogenetic analysis using the P3 sequence, which encodes an RdRP, revealed that LbQV-1 was most closely related to known and suspected quadriviruses and monopartite totiviruses rather than other quadripartite mycoviruses including chrysoviruses and alternaviruses. Of the remaining encoded proteins, LbQV-1 P2 and P4 are structural proteins but the function of P1 is unknown. We propose that LbQV-1 is a novel member of the family Quadriviridae.Peer reviewe

Management of Diseases and Pests of Oilseed Rape

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Effectiveness of Rlm7 resistance against Leptosphaeria maculans (phoma stem canker) in UK winter oilseed rape cultivars

© 2018 The Authors. Plant Pathology published by John Wiley & Sons Ltd on behalf of British Society for Plant Pathology. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.The Rlm7 gene in Brassica napus is an important source of resistance for control of phoma stem canker on oilseed rape caused by the fungus Leptosphaeria maculans. This study shows the first report of L. maculans isolates virulent against Rlm7 in the UK. Leptosphaeria maculans isolates virulent against Rlm7 represented 3% of the pathogen population when cultivars with the Rlm7 gene represented 5% of the UK oilseed rape area in 2012/13. However, the Rlm7 gene has been widely used since then, representing >15% of the UK oilseed rape area in 2015/16. Winter oilseed rape field experiments included cultivars with the Rlm7 gene, with the Rlm4 gene or without Rlm genes and took place at five sites in the UK over four cropping seasons. An increase in phoma leaf spotting severity on Rlm7 cultivars in successive seasons was observed. Major resistance genes played a role in preventing severe phoma leaf spotting at the beginning of the cropping season and, in addition, quantitative resistance (QR) in the cultivars examined made an important contribution to control of phoma stem canker development at the end of the cropping season. Deployment of the Rlm7 resistance gene against L. maculans in cultivars with QR in combination with sustainable disease management practices will prolong the use of this gene for effective control of phoma stem canker epidemics.Peer reviewe

Control of arable crop pathogens; climate change mitigation, impacts and adaptation

© Springer Science+Business Media New York 2016. This is the accepted manuscript version of an article which has been published in final form at https://doi.org/10.1007/978-1-4939-3536-9_3In the context of threats to global food security from impacts of damaging crop diseases and of climate change, this chapter describes three aspects of the interactions between climate change and diseases that reduce arable crop yields. It considers the role of crop disease control in climate change mitigation, by estimating consequences for greenhouse gas (GHG) emissions of crop management strategies to control diseases, using UK oilseed rape and barley crops as examples. In this chapter we conclude that good control of crop diseases, resulting in more efficient use of nitrogen fertiliser, can decrease UK GHG from crop production by c. 1.6 Mt CO2 eq. each year. Within the chapter we discuss impacts of climate change on incidence of crop diseases and their effects on crop yields, using UK oilseed rape phoma stem canker and wheat fusarium ear blight as examples. For both these diseases, it is estimated that global warming will increase the range and severity of epidemics. To make such estimates, it is emphasised that it is important to estimate impacts of climate on both crop growth and disease development. In response to such projections of impacts of climate change, within this chapter we assess strategies for adaptation to climate change of crop disease management to decrease arable crop losses related to climate change, for both policymakers and farmers.Peer reviewe

Diseases of winter linseed : occurrence, effects and importance

In 1998, a survey of the incidence and severity of diseases was carried out on 30 crops of winter linseed at early flowering and again at crop maturity. Five crops each were selected in south west, east, east Midlands, west Midlands and north of England and from Scotland. Crops were predominantly cv. Oliver (90% crops), grown from certified seed (83%) and sown in September (97%). Pasmo (Mycosphaerella) was the most important disease, affecting leaves of 73% crops at early flowering and 90% crops at maturity. Powdery mildew (70% crops), Alternaria (30% crops) on leaves and Botrytis on capsules (70% crops) were also common. Regional differences were apparent for powdery mildew, which was present in all regions except the southwest, whilst Alternaria predominated in the Midlands. Half of the crops surveyed had received fungicide sprays, but this appeared to have made limited impact on disease severity. Pasmo is a new threat to UK linseed crops and this raises concerns about the threat it poses to spring linsee

Evaluation of oilseed rape seed yield losses caused by Leptosphaeria biglobosa in central China

This document is the Accepted Manuscript version of the following article: Xiang Cai, Yongju Huang, Daohong Jiang, Bruce D. L. Fitt, Guoqing Li, and Long Yang, "Evaluation of oilseed rape seed yield losses caused by Leptosphaeria biglobosa in central China", European Journal of Plant Pathology, first published 9 June 2017. Under embargo. Embargo end date: 9 June 2018. The final publication is available at Springer via: http://dx.doi.org/10.1007/s10658-017-1266-x.Phoma stem canker of oilseed rape (Brassica napus), caused by Leptosphaeria maculans/L. biglobosa is a globally important disease. Severe phoma stem canker symptoms have been observed on winter oilseed rape in China but the seed yield loss caused by this disease remains unknown. In May 2012 and May 2013, 17 and 13 crops were surveyed, respectively, in seven counties of Hubei Province, central China. Stems with phoma stem canker disease symptoms were sampled for pathogen isolation and identification. Only L. biglobosa was identified by culture morphology and species-specific PCR; no L. maculans was found. To evaluate the yield losses, yield components (number of branches per plant, number of pods per plant, 1000-seed weight, number of seeds per pod) were assessed on healthy and diseased plants sampled from crops in four counties and on plants from inoculated pot experiments (plants of three cultivars were inoculated at the green bud stage by injecting L. biglobosa conidia into the stem between the first and second leaf scars). Results of the field surveys showed that diseased plants had 14–61% less branches and 32–83% less pods than healthy plants, respectively. The estimated seed yield loss varied from 10% to 21% and from 13% to 37% in 2012 and 2013, respectively. In the pot experiments, there were no differences in numbers of branches or pods but there were differences in number of seeds per pod between inoculated and control plants. For the three cultivars tested, the inoculated plants had yield losses of 29–56% compared with the control. This study indicates that L. biglobosa could cause substantial seed yield loss in China.Peer reviewedFinal Accepted Versio

Control of crop diseases through Integrated Crop Management to deliver climate-smart farming systems for low and high input crop production

© 2021 The Authors. Plant Pathology published by John Wiley & Sons Ltd on behalf of British Society for Plant Pathology. This is an open access article under the terms of the Creative Commons Attribution License. https://creativecommons.org/licenses/by/4.0/Crop diseases affect crop yield and quality and cause significant losses of total food production worldwide. With the ever‐increasing world population and decreasing land and water resources, there is a need not only to produce more food but also to reduce agricultural greenhouse gas (GHG) emissions to mitigate climate change and avoid land use change and biodiversity loss. Thus, alternative climate‐smart farming systems need to adapt to produce more food per hectare in a more sustainable way than conventional high‐input farming systems. In addition to breeding new high‐yielding cultivars adapted to future climates, there is a need to deploy Integrated Crop Management (ICM) strategies, relying less on synthetic inputs for fertilization and crop protection and less on fossil fuel‐powered machinery to decrease yield losses due to pest and pathogens and guarantee food security. In this review, we compare some low‐input farming systems to conventional agricultural systems with a focus on ICM solutions being developed to reduce synthetic inputs; these include crop genetic resistance to pathogens, intercropping, canopy architecture manipulation, and crop rotation. These techniques have potential to decrease crop disease frequency and severity by decreasing amounts and dispersal of pathogen inoculum and by producing microclimates that are less favourable for pathogen development, while decreasing GHG emissions and improving environmental sustainability. More research is needed to determine the best deployment of these ICM strategies in various cropping systems to maximize yield, crop protection, and other ecosystem services to address trade‐offs between climate change and food security.Peer reviewedFinal Published versio