Disease Note.

Lasiodiplodia theobromae and Fusarium proliferatum Causing Storage Rots of Taro on Guam. G. C. Wall, College of Agriculture & Life Sciences, University of Guam, Mangilao 96923. F. J. Cruz, College of Agriculture & Life Sciences, University of Guam, Mangilao 96923. Plant Dis. 75:1286. Accepted for publication 5 July 1991. Copyright 1991 The American Phytopathological Society. DOI: 10.1094/PD-75-1286D.

Taro (Colocasia esculenta (L.) Schott) corms normally last a month or more in storage at room temperature and 65-70% RH. Recently, entire lots have been spoiled in less than a week despite being stored at 22-24 C and 50% RH. Fusarium proliferatum (T. Matsushima) Nirenberg and Lasiodiplodia theobromae (Pat.) Griffon & Maubl. were isolated from infected corms. Koch's postulates were completed with both fungi by inoculating freshly harvested mature corms stored at 24 C and 50% RH; no infection developed in control corms. F. proliferatum (identified by P. E. Nelson and co-workers, Fusarium Research Center, Pennsylvania State University) produced a yellowish, spongy rot, sometimes found on the bottom of a freshly harvested corm. L. theobromae produced the most common symptoms observed only in storage, i.e., a brown, spongy rot starting near the bottom of a corm, progressing quickly upward, and eventually turning black, hence the common name spongy black rot. L. theobromae infected both mature corms and cormels by inoculation. This is the first report of taro storage rots caused by these fungi on Guam.