An interspecific hybrid in Allium

Abstract does not appear. First page follows.

Introduction

Porter and Jones,⁽⁵⁾ testing several varieties of Allium cepa L. and other species of the same genus, found that the Nebuka, a type of A. fistulosum, was markedly resistant to pinkroot, caused by Phoma terrestris Hansen, and showed no indication of injury when grown continuously for several years in heavily infested soil. Felix⁽²⁾ has also reported that varieties of A. fistulosum, namely Winterhecke and White Welsh as well as different strains of Nebuka (Natsu-negi Nebuka, Sinju negi Nebuka, Tokyo-Nebuka, Itwatsuki), are resistant to pinkroot. In addition, he states that the different strains of Nebuka are highly resistant to smut, caused by Urocystis cepulae Frost: although under favorable conditions, infection frequently averaged 10 to 20 per cent in the cotyledon stage, it always fell to 0.5 per cent or less in later counts. Anderson⁽¹⁾ also reports that the variety Winterhecke is resistant to smut. In a letter dated December 6, 1932, Professor A. G. Newhall of Cornell University states that seedlings from Nebuka seed grown at Davis, California, were practically immune to smut.

In a recent paper, Jones, Bailey, and Emsweller⁽⁴⁾ have shown that the Nebuka onion is also resistant to thrips, having a smaller number per plant than any other onion variety except White Persian, which it somewhat resembles in foliage characters, especially the circular leaves, spreading habit of growth, and long sheath region.