The potential of crop rotation in the management of bacterial wilt of potato in southwestern Uganda

Abstract

Bacterial wilt (BW) of potato (Solanum tuberosum) caused by Ralstonia solanacearum, is a major constraint to potato production in southwestern Uganda. It is a recalcitrant disease and one of the plausable management options is crop rotation. However, the suitable crops to be incorporated in a crop rotation regime with a view to reduce BW inoculum levels have not been systematically identified. Studies to identify crop(s) that would in the subsequent season delay on-set of wilt, reduce wilt incidence, lower latent infection, reduce Ralstonia solanacearum populations in the soil and increase tuber yield were conducted at Kachwekano Agricultural Research and Development Centre. Trials were carried out for three consecutive seasons during 2000A, 2000B, and 2001A in wilt-infested plots using the randomised complete block design. In 2000A and 2001A all study plots were under potato. The rotation crops (Sorghum bicolor, Triticum aestivum, Zea mays, Eleusine carocana, Ipomea batatas L., Daucus carota, Phaseolus vulgaris and Solanum tuberosum L.) were planted in the same plots during 2000B. Rotation with Sorghum bicolor, Triticum aestivum, Zea mays, Eleusine carocana, delayed on-set of wilt incidence, reduced wilt incidence and latent wilt infestation, and gave higher marketable tuber yield than the other rotation crops evaluated in the study. One-season rotation crops improved the shelf-life of consumption potatoes but not of seed tubers because of latent infections that were detected after subjecting the tubers to incubation at high temperature and indirect enzyme-linked immunosorbent assay on nitrocellulose membrane (NCM-ELISA).

Using any one of the evaluated rotation crops was assessed to reduce BW inoculum and was thus better than continuous cultivation of potato.