The EAHB is susceptible to pests (nematodes, banana weevils) and diseases (black Sigatoka, banana streak virus) (Gold, 1998, 2000; Gold et al. 1998, 1999; Gold, Pena, and Karamura 2001). Traditionally, farmers replaced a diseased endemic cultivar by replanting suckers of the same cultivar obtained from their fellow farmers within or outside the community. Often, this process inadvertently contributed to the spread of the pests and diseases, because farmers did not recognize infested or diseased planting material or fully understand the life cycles and transfer mechanisms of pests and diseases, especially given continual evolution of new races and pathogens. In areas along the lake shores in Bukoba and Muleba districts of Tanzania, in particular, as a growing rural population intensified banana production to meet their food and
cash needs, the performance of endemic banana cultivars deteriorated substantially.
Mat numbers for some endemic cultivars diminished or they disappeared altogether from individual farms and/or communities.
The extension services of the Depart-ment of Agriculture in Tanzania were able to recognize banana production constraints and attempted to address them through empha-sizing good crop husbandry, including the uprooting of diseased banana plants and use of insecticides. The impacts of their efforts were not impressive, however, given the high cost of insecticides and the difficulty for farmers to understand pest and disease com-plexes. Legacies from the colonial era did not improve farmers’ trust in government recommendations. For example, farmers re-sisted the order of the colonial government to uproot all bananas infested by weevils, in part because of misunderstandings (Kabwoto 1974). Toward the end of the 1960s, an in-secticide (dieldrin) was recommended for the control of banana weevils. The Bukoba Co-operative Union (BCU) supplied insecti-cides free of charge and during that time, 60 percent of the farmers applied the insecticide (Rald and Rald 1975). According to Bosch et al. (1996), after dieldrin application, farm-ers reported that banana plants fell over more frequently than before and complained that the insecticides “killed” their bananas.
Most of the farmers have since been reluc-tant to apply chemical of any sort, including artificial fertilizers, in their banana groves (FSR 1989).
In Uganda, banana researchers identi-fied host-plant resistance as one of the most feasible alternatives to control these prob-lems (Ortíz and Vuylsteke 1994; Tushe-mereirwe et al. 2000), adopting a
combina-tion of short- and long-term strategies. The short-term strategy includes the assembly of endemic and nonendemic germplasm for evaluation and selection of resistant or toler-ant cultivars, including the importation of hybrids from other breeding centers, such as FHIA in Honduras and IITA in Ibadan, Nigeria. The long-term strategy includes breeding for resistance in the National Ba-nana Research Programme, NARO, Uganda.
The objectives of the overall approach are to develop and disseminate banana genotypes that are resistant to local pests and diseases, have good agronomic characteristics, and are acceptable to end users. A time line identifying key dates and junctures in the history of banana research in Uganda is shown in Table 4.1. <Table 4.1 near here>
In addition to work with germplasm, NARO has recommended improved banana-management practices. Bananas are pro-duced by propagation continuously on the same piece of land, and therefore demand intensive management to sustain their yields.
Both management of the natural resource base and those related with the crop itself are recommended. Natural resource manage-ment practices used in banana production include: (1) application of dry organic mulch (in the form of grass or crop residues), (2) manure (that is, animal waste and compost-ing of household refuse), and (3) soil and water conservation bands. Farmers are also advised to carry out a number of other crop management practices to ensure good sanita-tion in their plantasanita-tions so as to reduce pest and disease infestations and facilitate the management of their soil fertility. Sanitation practices include: (1) corm paring,1 (2) de-trashing (removal of dry leaves and sheath), (3) desuckering (removal of excess plants on
1 In the traditional farming system, banana plantations are established with suckers of about 1.5 m high. The planting material is usually uprooted with its roots and soil and taken for planting in a new field. This method has disadvantages, because such planting materials can transmit pests (nematodes and weevils) and soil-borne diseases, such as Fusarium wilt, to the new field. Farmers have been trained to clean banana planting material by corm paring. Through paring, one is able to see tunnels formed by weevil larvae and necrosis due to nematodes.
As an additional treatment, it was demonstrated to farmers that pared planting material can be dipped in hot water at a temperature between 52°C and 55°C for 20 minutes or in a pesticide solution to kill the deeply embedded pests (Gold et al. 1998; Tushemereirwe et al. 2003).
IMPROVED BANANA CULTIVARS AND MANAGEMENT PRACTICES 39
a mat), and (4) other residue management practices (such as stumping and corm re-moval). Splitting pseudostems and weevil trapping are also recommended. Details of the banana-management practices recom-mended to farmers are described in Tushe-mereirwe et al. (2003).
In Tanzania, although no formal plant breeding is undertaken, banana growers have also worked to counteract these pest and disease pressures by procuring new, clean planting material for endemic culti-vars within and outside their communities, exchanging new cultivars with other
farm-ers, and adopting banana cultivars intro-duced by public and private extension ser-vices. Furthermore, the extension service has sought to curb pest and disease pres-sures through training farmers on good ba-nana-management practices. In mid-1997, the government of Tanzania and the King-dom of Belgium cofinanced a major effort to propagate and diffuse superior banana cultivars under KCDP.
Selection and improvement strategies pursued by farmers, researchers, and exten-sion agents are described next, following by a summary of dissemination mechanisms.
Table 4.1 Key dates in the history of banana improvement in Uganda
Activity Institution Year
Germplasm collection started Kampala plantation 1920
KARI 1940
Establishment of tissure culture (micropropagation)
Makerere University (banana) 1991
KARI (coffee) 1993
Germplasm collection and evaluation re-established
Makerere University–Kabanyolo 1989 KARI 1989
Banana micropropagation KARI/IITA 1995
Germplasm characterization KARI 1995–98
Germplasm evaluation for female and male fertility
KARI/IITA 1996–98
Cross pollination KARI/IITA 1996
Banana embryo culture KARI/IITA 1996
Cell culture KARI 1998–2007
Taxonomic and screening for conventional breeding
KARI 2000
Field testing of plants from single cells (cell suspension)
KARI 2002–07
Biotechnology lab opened KARI 2003
Sources: NARO/IITA annual reports; Makerere University, Faculty of Agriculture reports.
Notes: IITA is the International Institute of Tropical Agriculture; KARI is the Kawanda Agricultural Research Institute.