STUDIES ON SUNFLOWER RUST: I. SOME SOURCES OF RUST RESISTANCE

Abstract

Sunflowers (Helianthus annuus L.) and sunflower rust (Puccinia helianthi Schw.) are both apparently native to North America. Although sunflowers were used by North American Indians, they were first grown on a large scale as a source of edible oil in Russia. Their cultivation has since spread throughout the world, with the largest acreages in eastern Europe and South America. The rust is present wherever the crop is grown, and has been a limiting factor in production in some areas.Beacon, the first rust-resistant sunflower variety to be grown commercially, was produced in Manitoba and released to growers in 1955. It was derived from a single resistant plant which originated from a natural cross with wild sunflowers near Renner, Texas. Resistant plants have since been found in four other accessions from the Renner area, and in one from College Station, Texas. Varying degrees of rust resistance occur in selections from these sources, which have been carried through several selfed generations. Crossing studies have shown that resistance is dominant. Tests in South America indicate that lines derived from the Canadian material are resistant to rust in Peru and Argentina.