Harrington points way to Ryder Cup success
The issue has risen because more top European players are spending time on the US Tour, making it hard for them to schedule enough events on the continent.
Harrington is at St Leot-Rot near Heidelberg to defend his Deutsche Bank Tournament Players Championship of Europe, having spent a couple of weeks in Asia where he tied for fifth in the Macau Open and a disappointing 60th in his defence of the Asian Open in China.