Research reports on blackleg and soft rot in potatoes

AHDB research has included surveys of the bacteria causing blackleg and studies of when and how the bacteria enter early generation seed crops. Other projects have addressed the management of blackleg, including the impact of haulm destruction methods on disease.
The projects have been categorised according to the topics covered, to allow readers to identify the most relevant report(s).

Click on a project title below to access more information on the project and download the final report

Surveys of the bacteria causing blackleg in potatoes

Blackleg survey – English and Welsh seed crops (2010-2015)

  • samples of blackleg-infected plants, seen during seed classification inspections of potato crops in England and Wales, were tested to identify the bacteria causing the symptoms

 R437 Investigating the biology and appropriate control of Dickeya species affecting GB potatoes (2010-2013)

At the time there was increasing concern about the risks to potato production in GB posed by Dickeya solani. The project included:

  • comparison of the amount of disease caused by D. solani at different temperatures
  • assessment of the factors involved in the persistence and/or spread of D. solani in the field
  • evaluation of the effects of disinfectants on the survival of D. solani

 R290 Revised investigation of Erwinia chrysanthemi (Dickeya dianthicola and other Dickeya species) able to infect potatoes (2007-2008)

  • molecular methods were used to assess the distribution of Dickeya dianthicola and other Dickeya species
  • tested tubers, samples from watercourses and river weeds for Dickeya species
  • assessed whether the diagnostic methods available at the time were suitable for the detection, identification and enumeration of Dickeya species


How blackleg-causing bacteria get into early generation seed crops

R475 Routes of Pectobacterium atrosepticum (Pba) contamination of high-grade seed potatoes (2013-2016)

  • intensive monitoring of Pre-Basic crops over several years
  • experimental trials to monitor the spread of Pba from infected plots
  • monitoring systemic infection on different cultivars in greenhouse trials
  • modelling studies using Scottish seed crops data to investigate whether blackleg is a random event, or shows patterns / geographical clusters
  • field trials to compare the effectiveness of sulphuric acid with the haulm desiccation programmes that were possible at the time

 11120048 Application of machine learning to improve the prediction of blackleg (Pectobacterium atrosepticum) disease risk in potatoes (2019 -2022)

  • mining large datasets to identify patterns, and causal factors, in the occurrence of blackleg in seed crops in Scotland


 Management of blackleg and soft rot

11120031 Improved seed management to minimise losses due to Pectobacterium species (2017-2020)

  • review of how storage conditions affect the numbers of bacteria on tubers
  • testing mini-tubers for Pba
  • pot trials to understand the relative importance of soil vs aerial routes of contamination of seed crops
  • studying seed crops grown in isolation (on Orkney)
  • monitoring Pre-Basic stocks for Pba during storage, handling and transport
  • the toxicity of salt to Pectobacterium species in lab conditions

Investigating the importance of latent infection in causing potato tuber breakdown during storage and transit (2017-2020)

  • effect of transit and post-export conditions on disease development including soft rot

 R453 Evaluating the impact of haulm destruction method on development of disease in seed crops (2011-2012)

  • replicated field trials and large scale field comparisons of the effect of haulm destruction method on the contamination of progeny tubers by Pba
  • measurements of pit rot incidence and severity
  • measurements of Phoma species stem disease incidence and gangrene

R431 Haulm destruction and blackleg in seed production (2009-2011)

  • field trial to compare haulm pulverisation vs haulm desiccation with diquat on tuber contamination with Pba
  • testing for the presence of Pba in weeds in and around two fields with high levels of blackleg

R298 Effect of atmospheric components in potato storage on tuber characteristics (2007-2009)

  • effects of high carbon dioxide concentrations on disease risk in stored tubers

Diagnostics and disease management

11140009 Early Detection of Potato Storage Diseases by Gas Analysis (2012-2016)

  • efficacy of pre-symptomatic detection and monitoring of soft rot using gas analysis

R427 Reducing wastage and increasing shelf life of root vegetables during washing, packing and retailing (2009-2011)

  • feasibility of using antibody or DNA-based techniques in packhouses to rapidly quantify the numbers of soft rotting bacteria on tubers at intake and/or after washing
  • risk rotting categories (numbers of bacteria/tuber) developed

 R253 Improving decision making for the management of potato diseases using real-time predictive diagnostics (2004-2008)

  • sampling tubers from boxes in store
  • high throughput detection, quantification and identification of Pectobacterium and Dickeya populations on potato tuber stocks
  • relationship between Pba levels on seed and on progeny tubers

 807/224 Application of developments in Erwinia diagnostics for a better understanding of the biology of seed stock contamination and blackleg control (2001-2004)

  • interpreting diagnostic results for the selection and management of seed stocks
  • effect of irrigation and level of bacterial seed tuber contamination on blackleg levels
  • effect of seed tuber bacterial contamination on crop growth, emergence, ground cover, physiological aging, yield and tuber number
  • effect of roguing on development of blackleg and contamination of daughter tubers
  • storage conditions and bacterial tuber contamination


Novel control options

R419 Low molecular weight inhibitors of virulence factor production by Pba (2009-2012)