January 2009. A team of IPM CRSP scientists reported the cause of a virus disease outbreak in yardlong beans in Indonesia. Yardlong is a native of southeast Asia; it is known as kacang panjang in Indonesia and it produces delicious edible pods and beans that are popular for delicate flavor and nutritional value.
A severe epidemic of a plant virus disease emerged during 2008, devastating yardlong bean production in Bogor and West, Central, and Eastern Java. According to Drs Aunu Rauf and Tri Damayanti, Faculty of Agriculture, Bogor Agricultural University, Jl. Kamper, Darmaga Campus, Bogor, this was the first time the epidemic occurred in the country. Losses upwards of 80% occurred.
Plants showed bright yellow mosaic symptoms with malformed leaves. Some plants produced no pods; where they were produced they were twisted and had mosaic symptoms. Trifoliate leaves of young seedlings (10-14 day old) showed bright chlorotic spots and bright yellow mosaic symptoms.
Bean common mosaic virus (BCMV) was found in plants with symptoms.
BCMV has a wide host range and its occurrence has been documented in many countries around the world. It is likely that BCMV was introduced into Indonesia through imported yardlong seeds and secondary spread occurred by resident aphids, e.g., Aphis craccivora, leading to an epidemic.
This information has implications to yardlong bean production in countries around the world, since exotic strains of BCMV introduced through imported yardlong bean seed can spread to other legumes, like soyabeans, cowpea and beans.
The IPM CRSP project on insect-transmitted virus diseases in South and Southeast Asia funded by USAID is joining forces with Indonesian colleagues to develop science-based disease management strategies to prevent the outbreaks of BCMV in Indonesia.