VIEW ARTICLE

The Increase of Cercospora Leaf Spot in Sugar Beets and Periodicity of Spore Release. Jack R. Wallin, Research Plant Pathologist, Plant Science Research Division, ARS, USDA, Iowa State University, Ames 50010; Daniel V. Loonan, Research Technician, Plant Science Research Division, ARS, USDA, Iowa State University, Ames 50010. Phytopathology 62:570-572. Accepted for publication 30 December 1971. DOI: 10.1094/Phyto-62-570.

An exponential increase in the Cercospora leaf spot disease occurred over 18 days in August. Disease spread was fastest downwind from the inoculated row. Spore release increased sharply at 0800 hr, 1 hour after dew “burn off” was well underway and relative humidity had dropped below 90%, and was greatest at 1100 hr. Long nocturnal dew periods resulted in few spores aloft at night and more spores over the sugar beets the next day.