VIEW ARTICLE

Resistance to Verticillium Wilt in Collections of Wild Helianthus in North America. J. A. Hoes, Plant Pathologist, Research Station, Research Branch, Canada Department of Agriculture, Morden, Manitoba; E. D. Putt(2), and Henry Enns(3). (2)(3)Plant Breeders, Research Station, Research Branch, Canada Department of Agriculture, Morden, Manitoba. Phytopathology 63:1517-1520. Accepted for publication 20 June 1973. DOI: 10.1094/Phyto-63-1517.

Resistance to Verticillium wilt caused by Verticillium dahliae occurred in all 46 collections of wild Helianthus tested. Six collections of H. annuus were from Manitoba and Saskatchewan in Canada, and 34 collections of H. annus plus 6 collections of H. petiolaris were from 12 states in the United States. Resistance was confirmed in F₁, F₂, and F₃ populations of crosses of resistant wild plants with a susceptible inbred. H. petiolaris was generally more resistant than H. annuus. Collections of H. annuus from Manitoba, Saskatchewan, and North Dakota were generally less resistant than those from more southern latitudes. A center of resistance is postulated to exist in the central and southern Great Plains, which coincides with the hypothetical center of origin of H. annuus and H. petiolaris. Frequency distributions of F₁, F₂, and F₃ populations suggested dominance of resistance, and recessiveness or lack or dominance of resistance.