VIEW ARTICLE

Ecology and Epidemiology

Effect of Simulated Dew and Postinoculation Moist Periods on Infection of Soybean by Septoria glycines. J. P. Ross, Plant pathologist, U.S. Department of Agriculture, Science and Education Administration, Agriculture Research, and Department of Plant Pathology, North Carolina State University, Raleigh 27650; Phytopathology 72:236-238. Accepted for publication 3 June 1981. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1982. DOI: 10.1094/Phyto-72-236.

Experiments were conducted to determine if misting soybean foliage at night to simulate dew formation would affect the severity of brown spot disease. Soybean plants (cultivar Essex) were grown outside in 20-cm-diameter pots and inoculated at flowering with pycnidiospores of Septoria glycines. In 1979, lesions induced by S. glycines on plants exposed to a 44-hr postinoculation moist period (PMP) were compared to those on plants not exposed to the moist period. Daily simulated dews during the latent infection period caused increased infections on plants not exposed to the PMP. Dews every third or fourth day resulted in increased numbers of lesions on plants exposed to PMP. In 1980, treatments included PMP of various durations, two inoculum levels, and dews daily and every second or third day. Dew exposures again resulted in increased numbers of lesions; increasing the duration of PMP to more than 6 hr occasionally resulted in decreased numbers of lesions.