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July 2004. A message from a farmer in Solomon Islands: Why is Alomae so persistent on taro in Solomons and couldn’t it be eradicated. Is there any taro variety elsewhere in the Pacific that is resistant to Alomae.
It was suggested that some of the lines from the Papua New Guinea breeding program should be introduced to Solomon Islands for testing. As to the other question about why Alomae is so persistent, there was a long reply from a member who has worked on the viruses involved.
It is very difficult to answer your question on persistence of Alomae simply because there is much we still do not know about this disease. Based on some research done about 30 years ago, Alomae was thought to be caused by infection with two viruses (Colocasia bobone disease virus (CBDV) and Taro bacilliform virus (TaBV). More recent research by QUT in Brisbane has resulted in the characterisation of five taro viruses and the development of sensitive diagnostic tests. These tests have been used to survey Pacific Islands countries for taro viruses and have also provided information on the cause of Alomae.
When Alomae plants were tested for viruses, it was found that at least three viruses seemed to be associated with the disease (CBDV, TaBV and Taro vein chlorosis virus (TaVCV)). However, this is really only circumstantial evidence – the only way to really show what is causing alomae is to do virus transmission tests. Unfortunately, this has been very difficult to do because little is known of the insect vectors responsible for transmitting the viruses, and the insects are also very difficult to work with.
However, ways of infecting taro plants with viruses without using insects are now available and it is hoped to use these methods to determine the exact cause of Alomae. Hopefully, this information will allow the development of effective control strategies. For the time being, the best way to control Alomae is by removing infected plants and making sure the plot (garden) is kept free of weeds (since insects which transmit viruses can breed on weeds and then transmit the virus when they move onto the taro to feed). When removing infected plants, it is important to spray the plants first with something that immediately kills any insects on the plant (something like kerosene). If this is not done, any insects on the infected plant will fly off on to neighbouring plants and transmit the disease. Then the infected plants should be buried or burnt.
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