A Method for Determining Stem Canker Resistance in Soybean

Stem canker disease of soybean is caused by the fungus, Diaporthe phaseolorum var. caulivora, and at present there are no soybean varieties known to be highly resistant to this disease. Stem canker takes its name from the resemblance of the discolored area of an infected stem to a canker. As the infected area on a stem enlarges, the stem is girdled and the portion of the plant above the girdled area is killed. Stem canker seriously affects soybeans in the northcentral region of the United States and has been reported to cause heavy losses (Athow and Caldwell, 1954; and Dunleavy, 1954, 1955). A description of the disease and the casual organism has been published by Welch and Gilman (1948) and Athow and Caldwell (1954). Differences in varietal susceptibility have been reported by Hildebrand (1953a) and Beeson and Probst (1955)