Jensma, J. R.
During the year 1956 we tested 42 strains on their resistance to late blight (Phytophtora infestans). The strains were received from scientific workers engaged in breeding for resistance.
Growing was carried out in the open and the plants were left to natural infection, which occurred in a heavy degree, partly due to the very rainy summer we had.
None of the strains showed the slightest degree of resistance. Most likely a different physiologic race of Phytophtora is prevailing in the Netherlands.
Thanks are due to the following persons, who kindly supplied us with the seeds: Currence, Minnesota; Odland, Pennsylvania; Raleigh, North Carolina; Walter, Florida; Conover, Florida; Galleghy, West Virginia; Schroeder, New York; Ferguson, Canada.