1. Müller, K. O., and Börger, H., Arb. Biol. Reichenstalt Landu Forstwirtsch., 23, 189 (1940).
2. Yarwood, C. E., Phytopathology, 46, 540 (1956).
3. Bennett, C. W., US Dept Agric. Tech. Bull., 1218, 63 (1960).
4. Lovrekovich, L., and Farkas, G. L., Nature, 205, 823 (1965).
5. Schnathorst, W. C., and Mathre, D. E., Phytopathology, 56, 1204 (1966).