Arena Leisure and Northern Racing have been unable to extend the lease for Hereford from Herefordshire County Council and have subsequently decided to pull out of the venue.
Tony Kelly, managing director of Arena and Northern Racing, said: "Hereford is owned by Herefordshire County Council and run under a lease arrangement.
"Attempts to extend the lease, which has 17 years remaining, have been unsuccessful.
"Despite being unviable for several years we have supported the racecourse but much-needed investment, required to breathe new life into the racecourse, cannot be justified in the absence of a long-term future for the business."
Plans are afoot to cease trading at Folkestone at the end of the current season, subject to on-going negotiations with Shepway Council.
Kelly added: "Folkestone suffers from outdated facilities and has been the subject of detailed discussion between the previous management, Arena Leisure, and Shepway District Council for several years now.
"The proposal for the site incorporated significant residential development, which would have enabled a new racecourse to be constructed with much enhanced amenities.
"However, these plans have been delayed following the recent Examination in Public of the local plan.
"Discussions will continue with Shepway District Council in the hope that there will be approval of development plans which would secure the future of the racecourse.
"If they succeed, work to reconfigure the racecourse could commence in 2013."
Races currently scheduled for the two courses will now be rearranged for other courses run by Arena and Northern Racing.