ABACA Activities in the Philippines - Unido

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Ref. No. CFC/FIGHF/09 CFC/UNIDO/FIDA 32 1. Rationale Abaca (Musa textilis Nee) of the family Musaceae is indigenous to the Philippines. It is planted mainly as a source of fiber either raw, pulp or use for cordage and fibercraft. The Philippines supplies about 84% of the world requirement while Ecuador supplies 16% (FIDA, 2003). This major agricultural crop is planted to 121, 839 hectares with a production of 62,796 metric tons on which more than 1.5 million Filipinos, with an average of 2.5 hectares farm size, depend for a living, both directly and indirectly (FIDA, 2002). The recent fiber production has declined from year 2000 which could be attributed to the prevalence of the viral diseases which affected major abaca-growing areas. As of February 2003, a total of 22,518 hectares are affected by the disease with a slight to severe disease incidence. Bunchy-top was first reported in 1915 in Silang, Cavite (Ocfemia, 1924). It wiped out a total of 12,000 hectares in the provinces of Laguna, Batangas and Cavite and spread to nearby towns in the Bicol Region until Sorsogon Province. Bunchy-top was reported existing in Davao area in 1937 at a time when large plantations of abaca were under the control of the Japanese. It had slowly reached the areas of Eastern Visayas and affected several barangays. It was undoubtedly the most important disease which affected abaca from the time it was reported until now. Similar scenario was observed for abaca mosaic and bract mosaic diseases which also affected several farms in Albay, Sorsogon, Leyte and Samar areas and reached until Agusar Sur. Unless a new abaca variety is developed through unconventional means like genetic engineering and become available, it is important and practical alternative to identify which among our present varieties can continuously produce a profitable harvest even in the presence of these diseases. Thus, the Fiber Industry Development Authority (FIDA) with the additional financial support from the Common Fund for Commodities (CFC) through United Nations Industrial Development Organization (UNIDO) implemented this project to address this problem. 2. Objectives To identify which among the high-yielding abaca varieties possess some degree of resistance to abaca bunchy-top and abaca mosaic diseases and to determine the stability of resistance when planted in three different locations 3. Methodology Selection of Varieties All varieties deemed suited for commercial planting were identified but only 40 varieties passed the high yield criteria of 800 kg/hectare/year. The performance of the 40 varieties were evaluated based on the primary data generated in previously conducted agronomic trials (Catiempo & Macarayan, 2000; Lomerio & Oloteo, 2000; Romero et al. 2000). Field Testing of Varieties The protocol followed in the screening trials developed by Dr. Avelino D. Raymundo is an alternative methodology of screening for reaction of abaca germplasm to bunchy-top and mosaic viruses (1998). It is a quantitative approach to screening in a system where the disease is systemic and where resistance appears elusive and seemingly non-existent, as in abaca bunchy-top top disease. 3.1 Regional screening trials Selection of sites The trials were undertaken in the field where “hot spot” was well-chosen. A “hot spot” is a concentration of high inoculum which should sustain at least 50% disease incidence. Diseased plants were transferred to the area when needed. When the incidence was above 50%, the population of the diseased
Ref. No. CFC/FIGHF/09 CFC/UNIDO/FIDA 33 plants were reduced in order to maintain uniformity of the inoculum throughout the area. The test sites for the regional screening trials are abaca-growing areas in Albay where two sites were chosen, one for bunchy-top and one for mosaic; in Leyte, one site for mosaic only while in Davao, two sites, one for bunchy-top and one for mosaic. The experiment was laid-out in randomized complete block design (RCBD) with 4 replications, planted at a distance of 1 m x 1 m. Data were gathered from 20 samples from each replicate. Good agronomic practices, such as fertilization and ringweeding were followed except spraying of insecticide. As soon as shoots/suckers were observed, it was made sure that vectors were present in the infected sources of inoculum and the area was disturbed from time to time to induce movement of vectors. Disease measurement The varieties were assessed based on the following parameters observed and measured for a period of 8–15 months from emergence. 1. Incubation time –the time from estimated transfer of inoculum by vector to appearance of visual disease symptoms 2. Kinds of symptoms – yellowing, stunting, bunching – top, leaf curling, etc. 3. Stage of plant growth when specific symptoms appeared – developmental stages of the abaca plant will be monitored 4. Percentage disease incidence at weekly interval – the number of diseased plant relative to the total number of plants being tested 5. Area under the disease-progress-curve –representing the cumulative amount of disease at the end of a specified period computed as: A = Σ1/2 (X 1 – X i-1 ) where X i = amount of disease at one point 6. Infection rate – estimated by the equation r = (1/t 2 – t 1 ) (1n(x 2 /1- x 2 )- (1n(x 1 /1- x 1 ); it is an indication of the speed of disease development The varieties were rated based on the analyses. In general, a variety with lower infection rate, smaller AUDPC, flatter disease progress curve, longer incubation time was considered more resistant. Virus indexing of selected varieties for the national screening Indexing of selected entries by enzyme-linked immunosorbent assay (ELISA) in FIDA diagnostic laboratories in Albay, Leyte and Davao was undertaken before "exchange of planting materials" and transporting them to respective regions. Entries were indexed for the three viruses specifically bunchy-top virus (BTV in abaca), abaca mosaic virus (AbaMV) and bract mosaic virus (BrMV in abaca). 3.2 National Screening Trials Based on the results of the regional screening, the top three to four varieties per region were identified and subjected to national screening to determine the stability of the resistant varieties. It was also assumed that different virus strain might exist in each test location. Three varieties were identified for the Bicol Region namely Abuab, Lausigon and Musa tex 51; three for the Visayas namely Linawaan, Laguis and Inosa; and four for the Mindanao area namely Tangongon, Maguindanao, Kaunayan and Kutay-kutay. Unfortunately, varieties Kaunayan and Kutay-kutay were not included in the trial due to political crisis in the area during the time of exchange, thus only eight varieties were multiplied, indexed by enzyme-linked immunosorbent assay (ELISA) and included in the regional exchange. The national screening trials were located in a hotspot area as earlier defined also established in similar locations; Albay : two sites, one for bunchy-top and one for mosaic; Leyte: one site for mosaic; Davao: two sites, one for bunchy-top and one for mosaic. The experiments were laid out in RCBD with 4 replications, planted at 2.5 x 2.5 distance between hills and observed 20 samples per replicate. Initial disease observation was undertaken as in regional screening and continuously done at monthly intervals to ascertain the tolerance/resistance of the varieties based on their reaction to the virus. In addition, the following parameters were also considered;
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ABACA Activities in the Philippines - Unido

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