• Potatoes are a leading Scottish product with an estimated sector value of around £170 million.

• Scotland is one of Europe’s largest potato seed produces with a value of around £80-100 million.

• 75% of UK seed is produced in Scotland and 80% of UK seed exports are from Scotland.

• Scotland exports over 300,000t of seed (ca £72m), including to EU (ca £44m) and to over 25 non-EU countries (a record breaking year for non-EU exports in 2015/16) (ca £28m).

• Potato blackleg, caused mainly by Pectobacterium atrosepticum, is one of the most significant bacterial diseases affecting potato production in Scotland and is the main cause of seed failure and downgrading (up to 9% in 2011-12).

• In this study we used controlled environment experiments to quantify the disease-severity risk of blackleg under different temperature regimes.

• A model was developed and fitted to data for three Pectobacterium strains and one Dickeya strain.

• The model was used to project the future risk of crop damage due to blackleg for a range of time periods and CO2 emissions scenarios.

• We found that projected increases in temperature will result in increased risk of blackleg caused by P. atrosepticum in Scotland.

• Conditions are expected to favour P. atrosepticum over the other isolates investigated, therefore P. atrosepticum is expected to continue to dominate in Scotland unless new populations evolve that are better adapted to warmer conditions.