Merrimack: A new variety of potato resistant to late blight and ring rot and adapted to New Hampshire

Abstract

Merrimack is a variety of potato bred by the United States Department of Agriculture and tested in New Hampshire. Maine, and elsewhere as part of the work of the National Potato-Breeding Program. Merrimack competed favorably with standard varieties in New Hampshire. It produced satisfactory yields of potatoes, with a relatively high dry-matter content from which excellent chips and french fries were made. In the Maine tests it did not yield as well as some of the standard varieties but in tests it was found to be highly resistant to, if not immune from, the common race of the late blight fungus in both vines and tubers. It is moderately resistant also to early blight, and was apparently fieldimmune from virus A and highly resistant to net necrosis. Its vines are very susceptible to leaf roll virus. Merrimack is not only highly resistant to ring rot but is the first variety released that is highly resistant to both late blight and ring rot. Its multiple-disease resistance should make it valuable, especially to growers who find it difficult to control late blight and ring rot in standard varieties.