Scientists discover new abaca viral disease

LEGAZPI CITY -- Scientists from the Fiber Industry Development Authority (FIDA) and Australia have discovered a new viral disease called abaca bract mosaic which has infected thousands of hectares of abaca plantation in Bicol and Eastern Visayas.

The two FIDA scientists are Remedios Villa Juan-Abgona from FIDA Crop Research Division , Central Office; Emma O. Oloteo, a senior agriculturist, Albay Diagnostic laboratory; Dr. John E. Thomas, principal plant virologist of the Queensland Horticulture Institute, Australia; Murray Sharman and Cherie F. Gambley, technical researchers of the Department of Primary Industries (DPI), Australia.

They jointly published their findings in an article -- "First record of natural infection of abaca (Musa textilis) with banana bract mosaic potyvirus" in the Australian Journal of Plant Pathology.

Abaca is an important natural fiber crop and is closely related to edible banana and plantains.

FIDA regional director Ramon T. Borromeo said that the country produces an average of 65,000 metric tons of fibers from 1991 to 1998, generating an estimated export revenues of P2-billion annually and supplies 85 percent of the world demand.

But the abaca bunchy-top and abaca mosaic diseases have caused a significant decline in the production of abaca in Bicol and in Eastern Visayas. The abaca mosaic virus is caused by abaca mosaic potyvirus which is closely related to sugarcane mosaic potyvirus.

Bunchy-top is indicated by the malformations of the leaves and pseudostem's yellowish or whitish streaks on the abaca leaves, causing stunting of the infected abaca plants. In the advance stage of the disease, the leaves become mottled stiff, curl inward, fear along the margin and dry up eventually become shorter and narrower until it is almost devoid of leafblade.

The abaca mosaic disease, on the other hand, is characterized by the change of color of the leaves from dark green to light green or yellowish with spindle-shaped cholorotic streaks measuring 20 to 30 mm long by two to three mm wide running parallel to the leafveins and from the midrib to the leaf magins. Here, the streaks may have a rusty color on the blade, midrib and petiole of the leaf.

FIDA estimates 17, 411.81 hectares of abaca or 33 percent are infected of the total 52,664.0 hectares planted with abaca based on the recent abaca disease mapping last year.

The new abaca disease-the bract mosaic -- was thought to be caused by another strain of abaca mosaic virus.