Reaction of varieties and strains of winter wheat in loose smut

Two hundred and eighty-eight varieties and strains of winter wheat have been tested for resistance to loose smut by artificial inoculation in one or more years at one or more of the experiment stations at Denton, Tex., Manhattan, Kans., and Urbana, Ill. At the first two locations the tests were carried out under field conditions with bulk inoculum collected in nearby wheat-growing areas of each state, respectively, while at Urbana, collections from a wider area were used. Inoculation was effected with a hypodermic needle, using a water suspension of spores at Urbana. At Manhattan, the Moore vacuum spore suspension method was used. At Denton, the vacuum method was used the first five seasons, but during the last two seasons a hypodermic needle attached to a rubber bulb was used to inject dry spores into the spikelet. Pawnee is the only resistant variety of commercial hard red winter wheat available. The rust-resistant strains Kanred X Hope (C. I. 11976) and Hope X Turkey (C. I. 11964) showed low infection percentages at Denton, Tex., two seasons. Several Kawvale-Marquillo X Kawvale-Tenmarq strains were highly resistant at Manhattan and offer considerable promise because they also are resistant to rusts and to hessian fly. Among the soft red winter wheat varieties, the highest resistance was found in Currell, Kawvale (semihard), Leap, Thorne, and Trumbull. These varieties showed high resistance at all three locations. Many other varieties were resistant at one or more of the three stations and may offer possibilities as parental material resistant to certain races of loose smut. A number of Mediterranean X Hope strains, resistant to leaf and stem rust as well as loose smut, are valuable for breeding work in the Texas area. These include the named variety Austin. It is suggested that the most valuable parental material for breeding loose smut resistant varieties include the varieties Pawnee, Kawvale, Currell, Leap, Thorne, and Trumbull. The unnamed strains from the cross of Kawvale-Marquillo X Kawvale-Tenmarq appear of value because they combine resistance to loose smut with resistance to leaf and stem rust and to hessian fly. Likewise, the Kanred X Hope (C. I. 11976), Hope X Turkey (C. I. 11964), and the Mediterranean X Hope strains combine the Hope resistance to loose smut with good leaf and stem resistance. Differences in reaction of varieties at the several locations indicate physiologic race differences in the various inocula used. This suggests that caution should be used in the transfer of infected seed from one wheat-growing area to another to avoid the introduction of physiologic races not previously present there.