Effect of crop rotation pattern on soil bacterial wilt (Ralstonia solanacearum) population and potato (Solanum tuberusum l.) yield in Njoro, Kenya

Abstract

Poor soil fertility and high disease incidences particularly BW are the main constraints to potato production in Njoro, Kenya. Reduction of potato yield of between 30 – 70% has been attributed to bacterial wilt alone. Against this back drop, a trial was conducted in 2012 as part of a short-term crop rotation experiment (2 years) to investigate the effect of crop-rotation on soil bacterial wilt population and potato yield. The experiment was set up in a randomized complete block design (RCBD) with six crop rotation treatments and replicated four times. Four vegetables commonly grown in Njoro area, namely Garden Pea (GP), Carrot(C), Cabbage (CB), and Kales (K) were selected for the crop rotation sequence. These were rotated in a four season-experiment as follows: CB-P-K-P, K-P-CB-P, C-P-C-P, GP-P-GP-P, K-P-K-P and P-P-P-P a no rotation control treatment of continuous potato. Data collected included selected soil chemical properties, soil BW pathogen count, BW incidence, plant growth and crop yield. The parameters measured in soil properties were pH, N, P K, and soil organic matter. Soil BW pathogen count and B.wilted plant were the biological parameters considered. Finally the stem heights at bulking and fresh potato weight at harvest were the parameters for plant vigor and yield. The results collected at the end of fourth season showed that crop rotation pattern at (p < 0.05) had effect on soil pH and available P in the control rotation pattern P-P-P-P. BW count was found to be below infection level (30 cfu g-1) which does not cause infection. There was also significant effect of crop rotation sequence at p < 0.05 on BW incidence, plant vigor and potato yield compared to the control treatment P-P-P-P. Crop rotation therefore remains the most effective way of managing and controlling effect BW pathogen in potato production. Keywords: Bacterial wilt, Crop rotation sequence, Bacterial wilt incidence