New potato varieties

Summary

Breeding potatoes for disease resistance is being emphasized in the cooperative potato-breeding program which is carried on between the United States Department of Agriculture and a number of the State Experiment Stations.

A large number of varieties have been produced that are resistant to one of the commonest virous diseases known as mild mosaic. Two of these have been named and are being distributed. One seedling at least is resistant to another virus, latent mosaic. An effort is being made to combine the resistance to the mild and to the latent mosaic in a single variety.

Tests of a large number of varieties and seedlings are being conducted to find varieties which show resistance to two other virous diseases—leaf-roll and spindle tuber.

Several varieties and seedlings are available which showed resistance to late-blight during the blight epidemic year of 1932. Comparatively no blight developed in 1933 and as a result the field test for late blight resistance was a failure. None of the seedlings apparently resistant to late blight are very promising from the commercial standpoint but the best of them are being used as parents in the work of breeding for blight resistance.