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Plant virology in sub-Saharan Africa 62% have been reported (Estelitta et al. 1996). The virus is currently considered an emerging threat to the cultivation of banana in Kerala, India, especially where cucur-bitaceous vegetables are cultivated as intercrops in banana (Estelitta et al. 1996). It is especially important to control CM V where mass propagation of in vitro banana materiał is employed, as levels of CMV in these plantings can be high.

While considered worldwide in its distribution, CMV and CMV strains have been reported for the first time on bananas in a number of developing countries recently, prob-ably due to the availability of efficient detection and identification methods (Doon 1991; Zambolim et al. 1994; Castano et al. 1994; Rivera et al. 1992; Osei 1995; Srivastava et al. 1995; Allam et al. 1995; Li et al. 1996; Pietersen et al. 1998).

To control CMV, it is essential to ensure that source plants used for propagation are free of virus. Highly reliable diagnostic techniąues exist which allow this to be accomplished. Elimination of weed hosts from plantations and surrounding areas also help to control the virus. Furthermore, banana plantations should not be close to crop hosts of CMV (e.g., cucurbits, tomatoes, and tobacco).

Banana mi Id mosaic virus (BanMMV)

Recently, previously uncharacterized filamentous virus particles have been noted in bananas from Africa, the Americas, southeast Asia, and Australia (Lockhart 1995; Thomas et al. 2000). Recent evidence suggests that the same virus is present in all these areas (Thomas et al. 2000). The virus is widespread within international germplasm collections (Thomas, Iskra-Caruana, and Pietersen unpublished). The widespread naturę of the virus, soon after being detected for the first time, suggests that it may be worldwide in its distribution. The virus has not been associated with a specific disease of banana thus far, but appears to increase the severity of the symptoms of BSV when it co-infects plants (Tushmereirwe et al. 1996). The economic impact of the virus thus far is unknown. The virions of BanMMV are flexuous filaments about 580 nm long and 14 nm wide. An isolate of the virus from cv. Ducasse has been sequenced and although related to Potex-, Carla-, and Foveaviruses, it appears distinct from all previously described virus genera (Gambley and Thomas 2001).

Banana bract mosaic virus (BBrMV)

Banana bract mosaic disease was first noted in 1979 in the Philippines, at Davao on the Island of Mindanao (Thomas and Magnaye 1996). It has subseąuently been shown to be widespread in the Philippines, India, and Sri Lanka (Rodoni et al. 1997; Thomas et al. 1997). A potyvirus has been isolated from infected plants and is assumed to be the causal agent (Thomas and Magnaye 1996). Yield losses of up to 40% have been recorded in the Philippines on cv. Cardaba and cv. Lakatan (Magnaye 1994). The disease

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