The last-eight clash at the ITF Pro Circuit tournament was the standout match of the day but Watson was able to complete only four games, reportedly because of food poisoning.
The result means Konta will hold on to her British number two position and is close to being ranked highly enough for direct entry into the Australian Open in January.
Watson, meanwhile, faces having to qualify for a grand slam for the first time since the French Open in 2012.
It has nevertheless been an encouraging end to a very difficult season for Watson, who has struggled since being diagnosed with glandular fever in the spring.
The 21-year-old won three matches in a row for the first time all season in Poitiers last week to begin what she hopes will be a rapid climb back into the top 100.
Konta will play Russian Marta Sirotkina in the semi-finals while Britain's other representative in the last eight, Naomi Broady, lost 6-4 6-3 to top seed Annika Beck of Germany.