VIEW ARTICLE

Bacterial Blight of Soybeans: Epidemiology of Blight Outbreaks. Gilbert C. Daft, Former Research Associate, Ohio Agricultural Research and Development Center, Wooster 44691; Curt Leben, Professor, The Ohio State University, Columbus, 43210. Phytopathology 62:57-62. Accepted for publication 22 July 1971. DOI: 10.1094/Phyto-62-57.

The relationship of wind-rain storms to the initiation of bacterial blight outbreaks incited by Pseudomonas glycinea on leaves of soybean (Glycine max) was investigated. Initiation of outbreaks on young leaves occurred during three wind-rain storms. Lesions were often associated with obviously injured areas. Even though inoculum was present, little disease was initiated in the absence of storms or during rain without wind. Inoculum was transferred from plants with leaves showing lesions to healthy leaves of the same and adjacent plants during simulated and natural storms. This was shown by the development of new lesions and the presence of the pathogen in leaf surface water. The wind component of storms was an essential factor in disease initiation. When closely grouped greenhouse and field plants were agitated by wind and immediately subjected to inoculum in the form of gently falling mist, abundant blight developed on leaves. During natural or simulated wind-rain storms, lesions were not initiated on all leaves; only one to two of the youngest open leaves of a plant were infected.