Full Length Research Paper

Current status of bacterial -speck and -spot diseases of tomato in three tomato-growing regions of Tanzania

K. C. Shenge¹*, R. B. Mabagala² and C. N. Mortensen³

¹Department of Crop Protection, Ahmadu Bello University, P.M.B. 1044 Zaria, Nigeria.

²Department of Crop Science and Production, Sokoine University of Agriculture, P.O. Box 3005, Morogoro, Tanzania.

³Danish Seed Health Centre for Developing countries, Department of Plant Biology, Plant Pathology Section, The Royal Veterinary and Agricultural University, Thorvaldsensvej40, Frederiksberg C, DK-1871, Copenhagen, Denmark.

*Corresponding author. E-mail: kcshenge@yahoo.co.uk , kcshenge@abu.edu.ng.

Tel: +234 806 764 7583.

Accepted 5 March, 2010

 Abstract

Disease surveys were conducted in Arusha, Dodoma, Iringa and Morogoro regions in Tanzania in 2004 and 2005, to establish the current status of bacterial -speck and -spot diseases of tomato. The surveys also aimed at assessing the effect of cultural practices on the two diseases, with the aim of determining suitable management options. Information was also collected through oral interviews on the sanitary conditions of the fields, land use intensity, source of seeds, and chemical application. Results of the surveys indicated that bacterial -speck and -spot were widespread in farmers’ fields throughout the study area. All the farmers interviewed applied pesticides to control tomato diseases. Data collected showed a positive correlation between field weediness and disease occurrence, indicating that field sanitation would be an effective way of reducing the two tomato diseases. There was a positive correlation between tomato variety and disease, and the locally available varieties were all susceptible to bacterial -speck and -spot. Of 104 tomato disease samples collected, 65 were found to be affected by the bacterial speck pathogen (Pseudomonas syringae pv. tomato), and 39 fruit samples were found to be affected by the bacterial spot organism (Xanthomonas campestris pv. vesicatoria). Screening of tomato seeds procured from the open market showed that they were not infected with P. syringae pv. tomato and X. campestris pv. vesicatoria.

Key words: Bacterial speck, Pseudomonas syringae pv. tomato, bacterial spot, Xanthomonas campestris pv. vesicatoria, management options.