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Namanda S.,International Potato Center Uganda | Gibson R.,International Potato Center Uganda | Gibson R.,Natural Health Group | Sindi K.,CIP Sub Saharan Regional Office
Journal of Sustainable Agriculture | Year: 2011

Surveys were made of the seed systems used in Uganda, Tanzania, and Rwanda and to investigate the reasons underlying them. Along the equator in Uganda, where rainy seasons are evenly spaced and occur twice a year, vine cuttings from mature plants only are used as planting material. Where there is a long dry season, the seed system includes a diversity of means of conservation: the passive production of volunteer plants from groundkeeper roots sprouting when the rains come; small-scale propagation of plants in the shade or backyard production using waste domestic water; and relatively large-scale propagation in wetlands or irrigated land. The last is the only means of obtaining sufficient quantity for sales, but is also the most expensive. Volunteers only produce planting material one or two months after the start of the rains and tend to be regarded as common property; nevertheless, they are an important source of planting material for poorer farmers. Although farmers perceive multiple benefits from planting early, planting material is in short supply at the beginning of the rains and mainly larger scale farmers gain these benefits. Farmers select carefully to avoid using plants with symptoms of virus disease as planting material and may also remove any diseased plants from crops. © 2011 Copyright Taylor and Francis Group, LLC.

Namanda S.,International Potato Center Uganda | Amour R.,Lake Zone Agricultural Research and Development Institute Ukiriguru | Gibson R.W.,International Potato Center Uganda | Gibson R.W.,Natural Resource Institute
Journal of Crop Improvement | Year: 2013

Ugandan farmers preferred vine cuttings from sweet potato (Ipomoea batatas (L) Lam.) plants maintained during the dry season in a swamp or by irrigation as planting material rather than cuttings from volunteer plants growing from unharvested roots. The latter were late and weevil-infested, though readily available. To improve their earliness, roots planted 5, 10, 15, or 25 cm below ground at the start of the dry season were watered from 5 or 10 weeks before the start of the rains. Only those planted 10 cm deep emerged satisfactorily; those watered for 10 weeks produced more vines. To improve survival, roots were stored under various conditions before planting and watering: roots stored in dry sand in a roofed building survived especially well and sprouted prolifically, producing many cuttings. This method of producing vine cuttings, called the Triple S method, was validated by farmers in the Lake Zone of Tanzania, which has a harsher climate than Uganda. In addition to providing farmers with ample early and healthy planting material for little and infrequent watering, it provided convenience and ownership. We would like to thank the many farmers and extension agents that supported us in Uganda and Tanzania but particularly Mr. Ekinyu and Mr. Sois. We also thank the Reaching End Users Project of HarvestPlus and the Sweet Potato Action for Security and Health in Africa Project of the International Potato Center. Dr. Ricardo Labarta assisted us with the design of the survey instrument. © 2013 Copyright Taylor & Francis Group, LLC.

Kakuhenzire R.,International Potato Center Uganda | Lemaga B.,International Potato Center Uganda | Kashaija I.,Kachwekano ZARDI | Ortiz O.,International Potato Center | Mateeka B.,Kachwekano ZARDI
Biopesticides International | Year: 2013

Potato (Solanum tuberosum Lin.) in tropical highlands (TH) is threatened by bacterial wilt (BW) caused by Ralstonia solanacearum (Rs). Technologies for reducing soilborne Rs are imperative in order to maintain supply of BW-free seed for sustainable high potato yield. Thus, experiments were conducted in S.W. Uganda in a BW endemically-infested field at 2200 m above sea level to test the effect of Crotalaria falcata as a component of crop rotation practice, soil fertility improvement and fallowing as a means of reducing or eliminating Rs inoculum in open fields for production of clean potato tubers. A one-year C. falcata fallow reduced BW incidence by > 85% compared to beans (43.9%), maize (37.6%) or natural fallow (27.0%). More than 97% of tubers from plots previously infested with Rs and cropped with C. falcata for 6-12 months had no visible BW symptoms compared with < 50% of tubers from plots continuously planted with potato. Apparently healthy tubers from plots previously planted with C. falcata were free from latent Rs infection but not tubers from plots formally kept under natural fallow for two years, or alternately planted with maize, beans, cabbage and onion. The effects of C. falcata on suppression of foliage BW and latent Rs infection in tubers were evident and profound. Crotalaria falcata can, therefore be included in the crop rotation and land fallowing practice for effective prevention of both visible and latent Rs infection in seed and sustaining high ware potato yield among small holder farmers in tropical highlands. © 2013 (KRF).

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