VIEW ARTICLE

Ecology and Epidemiology

Persistence of Pseudomonas solanacearum (Race 1) in a Naturally Infested Soil in Costa Rica. M. T. Jackson, Horticulturist, International Potato Center, c/o CATIE, Turrialba, Costa Rica, Present address of senior author: Dept. of Plant Biology, University of Birmingham, P.O. Box 363, Birmingham, England, B15 2TT; L. C. González, plant pathologist, Facultad de Agronomía, Universidad de Costa Rica, San José, Costa Rica. Phytopathology 71:690-693. Accepted for publication 21 November 1980. Copyright The American Phytopathological Society. DOI: 10.1094/Phyto-71-690.

The persistence of Pseudomonas solanacearum in an inceptisol was studied at Turrialba (600 m above sea level) in Costa Rica. The relative inoculum level in the soil after different crop rotations and weed management practices was determined indirectly by an assay based on the percentage of wilted plants of bacterial wilt-susceptible and tolerant potato clones growing in this soil. Cultivar Atzimba was highly susceptible, whereas clone MS 35-22 had a high level of tolerance in trials in which maize, sweet potatoes, and kudzu were used in the rotations. No crop significantly reduced the relative inoculum potential. No effect could be demonstrated in other crop rotations in which maize, cowpeas, wilt-resistant tomatoes, and sweet potatoes were used. The severity of the disease on potato was significantly reduced only in plots in which weeds had been eliminated by a contact herbicide. In this case, the surface of the soil was exposed for 4 mo in contrast to those plots in which weeds either were controlled through tillage or allowed to grow in a weed fallow treatment.