New Varieties of Wheat.

by B. B. BAYLES

MORE THAN 50 improved varieties of wheat have been distributed to American farmers in the past decade. They resist rust, smut, other diseases, drought, insects, or winterkilling, major hazards that threaten crops always in one place or another. They increased our total wheat production by more than 800 million bushels in the years 1942 to 1946.

Most of them were developed at State agricultural experiment stations in breeding and testing work in which the Department of Agriculture cooperated and which is closely coordinated in each of the four main wheat-growing regions—hard spring, hard red winter, soft red winter, and western. All varieties developed in these programs are carefully tested to determine where they are adapted for growing and to insure that the grain quality of those released is satisfactory.

Varieties resistant to stem rust, released for growing in the preceding decade, occupied more than 12 million acres of the 15,700,000 acres of hard red spring wheat grown in 1944. This class of wheat predominates in the northern Great Plains and Prairie States, where stem rust formerly caused losses as high as 100 million bushels in some years. Approximately two-thirds the total acreage was sown to varieties resistant to both stem and leaf rust in 1946. Some of them also resist stinking smut and loose smut and one of them withstands the hessian fly.

Thatcher, the first extensively grown hard red spring wheat that is highly resistant to stem rust, was developed in cooperation with the Minnesota Agricultural Experiment Station and released in 1934. Because of its spectacular performance during the stem rust epidemic of 1935, when other varieties were badly damaged, it increased rapidly. By 1939 it was grown on an estimated 14.5 million acres in the United States and Canada. The acreage continued to increase until it was partly replaced by varieties resistant to both stem and leaf rust. In 1944 the acreage of Thatcher in the United States had decreased to 4.5 million but had increased in Canada to nearly 17 million. Before the distribution of Thatcher, stem rust had caused such heavy losses to Marquis and later to Ceres, the susceptible varieties then grown, that the damage from leaf rust was scarcely apparent. But when the stem-rust-resistant but leafrust-susceptible Thatcher was grown on large acreages the plants undamaged by stem rust were attacked by leaf rust.

Wheat breeders had foreseen this possibility and had been developing adapted varieties that could also withstand leaf rust. The first of these—Renown, a beardless variety was developed at Canadian experiment stations and distributed in 1937. Pilot and Rival, two high-yielding bearded varieties, were distributed from the North Dakota Experiment Station in 1939. These are resistant to both stem and leaf rust as well as bunt; Pilot is also resistant to mildew. By 1944 Rival was grown on 4,050,000 acres and Pilot on 1,216,000 acres.

Regent, another beardless variety distributed in Canada in 1939, resists stem rust and bunt, and is fairly resistant to leaf rust. It was grown on about 1,334,000 acres in the United States in 1944.

Four other hard red spring varieties were distributed between 1944 and 1946. All merit special mention. They are Mida, in North Dakota; Newthatch, in Minnesota; Henry, in Wisconsin; and Cadet, in North Dakota. Mida is bearded, medium early, high-yielding, and highly resistant to stem rust, leaf rust, and bunt. It is also somewhat resistant to the hessian fly. It was extensively grown in 1946, but its tendency to shatter, susceptibility to loose smut, and the greater injury suffered by it during the late 1946 spring freeze may retard its increase. Newthatch resembles Thatcher, except that it has more resistance to leaf rust. Henry is resistant to stem rust and is more resistant to leaf rust than other commercial varieties. It is recommended for growing only in Wisconsin, because its milling characteristics differ in some respects from other recently developed, high-quality, hard red spring wheats. Cadet is an excellent beardless type that compares favorably with the other varieties in resistance to both stem and leaf rusts. It performed well in 1946.

Rescue, a still newer variety, was developed by breeders at the Swift Current Station in Saskatchewan to combat losses from the wheat stem sawfly in sections of Canada and Montana. It has shown promise in tests where the sawfly does damage, but it does not resist leaf rust, bunt, or mildew.

The stem rust susceptible Durum varieties, Kubanka and Mindum, are now being replaced by two new varieties, Carleton and Stewart, both highly resistant to stem rust. They have excellent grain quality and were first distributed in North Dakota in 1943.