The Philippines, being the world’s leading producer of abaca fiber, has been reported to supply about 84 % of the global abaca requirement followed by Ecuador which supplies about 16 % fiber requirement (FIDA 2009). The abaca industry has been found to maintain a stronghold in both national/domestic and international markets since 1989 as the demand for raw abaca fibers or processed products has grown to a great extent and is expected to grow further with the advancement in technology and scientific formulations which will ultimately boost the Philippine economy. Moreover, with the availability of new international markets, the demand of abaca fibers (raw) or the processed products has increased to a great extent which is reflective of the marginal increase in its export. As per the reports, the export volume of abaca products has registered a growth rate of 121.4 % per year (Lalusin

2010) . The growing concern for environment protection or forest conservation is an important reason of ever-increasing demand for natural fibers, so is the case with abaca and there is an expectation that the demand will continue to increase keeping in view the potential of the fiber and its processed products. Despite the increasing demand and higher market prize, the production of abaca has not been found to keep pace with the demand. The main reasons for this gap between demand and supply are the low yield and low fiber quality (Moreno 2001) . Moreover, low — income generation from abaca farming, the laborious process of fiber extraction and availability of less human resources (who prefer jobs than traditional farming) is also responsible for its reduced productivity. Furthermore, the old typhoon dam­aged or disease-infected plantations (Sharman et al. 2000a, b; Villajuan-Abgona et al. 2001) add to the problem. Banana bunchy top virus (BBTV), Banana bract mosaic virus (BBrMV), Abaca mosaic virus (AMV), and Cucumber mosaic virus (CMV) are the four main viruses which have been found to infect abaca plants (Bajet and Magnaye 2002; Furuya et al. 2006; Pietersen and Thomas 2001; Pinili et al. 2011; Sharman et al. 2000a, b) of which BBTV (transmitted by banana aphid; Pentalonia nigronervosa Coq) has been reported to contribute to huge economic loss and resulted in destruction of many abaca plantations in Philippines (Calinisan 1939; Raymundo and Bajet 2000). Recently, the mutation breeding program has been initiated to produce virus-resistant (BBTV and BBrMV) abaca cultivars by using gamma irradiation (Cobalt 60) in two abaca cultivars Tangongon (TG) and Tinawagan Pula (TP) (Dizon et al. 2012).