PGR News from the Pacific

Posted 4:24 PM by Luigi

Protecting kava from kava dieback disease

Dr Richard Davis, the SPC virologist will be interviewed for the "In the Loop" programme of Radio Australia. Below is the information he provided. Richard will be going on air at 12.40 Fiji time on Tuesday July 26.

Kava

Kava is a crop of enormous cultural and economic significance in the Pacific Islands. There is a huge potential export market for kava, which may immediately take off again, following the recent lifting of a ban on kava sales in Europe.

Kava dieback

Kava dieback disease is a devastating problem. Affected plants develop a black soft rot, and ‘melt down’ rapidly. It spreads quickly and can destroy entire plantings.

It was first reported in Fiji in 1932. It then became the principal kava production constraint in the Pacific, especially in Fiji, Tonga, Samoa, and Vanuatu. In Fiji islands today, annual losses to kava dieback are estimated to average 40%.

In Fiji Islands, kava dieback reached serious national epidemic proportions in the late 1990s. This is because production intensity driven by high export prices, became very high. The threat today is that this story will be repeated if poorly planned rapid expansion of kava production occurs again.

The cause of kava dieback disease

The cause of kava dieback remained a deep mystery over decades of investigation until the early 1990s when an Australian (ACIAR) funded research project brought together workers from Tonga, Fiji, Vanuatu and Samoa. At last, progress was made: a plant infecting virus called Cucumber mosaic virus (CMV) was implicated. However, we know today that it is not such a simple story. Latest thinking is that dieback results from a complex of interactions of kava with environmental and other factors with CMV at its centre. Exactly what is involved probably varies in different places and at different times. However, one thing is crystal clear: take CMV out of the picture and you do not have dieback any more.

Tackling the problem

Controlling CMV is not easy. There is no ‘silver bullet’ answer for kava farmers. No suitable disease resistant varieties of kava have yet been found. There are no chemical sprays available which kill the virus in infected plants. Spraying to kill the insects which spread the disease from plant to plant does not give effective control either. All this is made worse by the fact that CMV is very common and can infect an extremely broad range of other plants.

Since the mid 1990s, no further research was undertaken on kava dieback until late 2002 when the Fijian Ministry of Agriculture, Sugar and Land Resettlement (MASLR) and the Secretariat of the Pacific Community (SPC) started work together. Funding was provided by the European Union’s Plant Protection in the Pacific (PPP) project, managed by SPC. As a first step, a major biotechnology upgrade at the Ministry’s Koronivia Research Station and at the University of the South Pacific was made.

Biotechnology, including the DNA analyses used in forensic police work, has now unlocked the door to understanding kava dieback. New breakthroughs have been made that provide the foundation for an integrated dieback disease management package. It will be based on a combination of simple actions growers can take that reduce the sources of the virus and suppress plant to plant spread - no pesticides involved, and all in an agroforestry context.

This package takes advantage of two principal weaknesses of CMV:

The virus is unable to completely infect and spread through all parts of kava plants
It is easily lost from the mouthparts of the insects that spread it when they feed on non hosts.

Details are now being finalised, but the package is basically:

1. Start with healthy plants

Growers must only use uninfected planting material. In the short term, this can be achieved to some extent by very carefully advised selection from what is currently available in the field. In the longer term, virus tested kava planting material should be made available, hopefully by commercial tissue culturing.

2. Slow the spread of the disease from plant to plant when it appears

If a kid has flu virus, the best thing to do is keep him or her out of the classroom, to prevent spread to the other kids. As plant diseases are like human ones, growers were first advised to destroy all diseased plants, before they infect their neighbours. This was never widely adopted because each plant is of high value and growers know that some new growth follows stem rot.
Since then, it has been discovered, using biotechnology, that many symptomless stems and new growth on infected plants are virus-free. This implies that vigilant removal of only kava stems showing early signs of disease could be an effective policy. How well this practice works is now being tested by both scientists and growers in Fiji and Tonga.

3. Smart cropping: use natural barriers to reduce the spread of the disease

Kava is best intercropped in early stages of growth and planting non-hosts between kava plants will reduce within plot spread of CMV. Studies to determine which key kava intercrops and weeds are alternative hosts for the dieback causing strain(s) of CMV are progressing well and definitive advice for growers is imminent.

4. Choose a good planting location

Dieback is much less of a problem when grown in the traditional way. That is in small and isolated plantings grown amongst natural vegetation and below a tree canopy. This is because many of these plants are not hosts to the disease. Because of this, they act as a buffer zone, protecting the kava from incoming insects carrying CMV. The more separated the plantings are from each other, the better this works.

Kava also seems to be less likely to develop dieback when CMV is around when it is growing vigorously. For this reason, growers should only plant in the right kinds of soils: well drained, fertile and high in organic matter.



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DIVA-GIS	Monday, July 25, 2005 Posted 4:24 PM by Luigi Protecting kava from kava dieback disease Dr Richard Davis, the SPC virologist will be interviewed for the "In the Loop" programme of Radio Australia. Below is the information he provided. Richard will be going on air at 12.40 Fiji time on Tuesday July 26. Kava Kava is a crop of enormous cultural and economic significance in the Pacific Islands. There is a huge potential export market for kava, which may immediately take off again, following the recent lifting of a ban on kava sales in Europe. Kava dieback Kava dieback disease is a devastating problem. Affected plants develop a black soft rot, and ‘melt down’ rapidly. It spreads quickly and can destroy entire plantings. It was first reported in Fiji in 1932. It then became the principal kava production constraint in the Pacific, especially in Fiji, Tonga, Samoa, and Vanuatu. In Fiji islands today, annual losses to kava dieback are estimated to average 40%. In Fiji Islands, kava dieback reached serious national epidemic proportions in the late 1990s. This is because production intensity driven by high export prices, became very high. The threat today is that this story will be repeated if poorly planned rapid expansion of kava production occurs again. The cause of kava dieback disease The cause of kava dieback remained a deep mystery over decades of investigation until the early 1990s when an Australian (ACIAR) funded research project brought together workers from Tonga, Fiji, Vanuatu and Samoa. At last, progress was made: a plant infecting virus called Cucumber mosaic virus (CMV) was implicated. However, we know today that it is not such a simple story. Latest thinking is that dieback results from a complex of interactions of kava with environmental and other factors with CMV at its centre. Exactly what is involved probably varies in different places and at different times. However, one thing is crystal clear: take CMV out of the picture and you do not have dieback any more. Tackling the problem Controlling CMV is not easy. There is no ‘silver bullet’ answer for kava farmers. No suitable disease resistant varieties of kava have yet been found. There are no chemical sprays available which kill the virus in infected plants. Spraying to kill the insects which spread the disease from plant to plant does not give effective control either. All this is made worse by the fact that CMV is very common and can infect an extremely broad range of other plants. Since the mid 1990s, no further research was undertaken on kava dieback until late 2002 when the Fijian Ministry of Agriculture, Sugar and Land Resettlement (MASLR) and the Secretariat of the Pacific Community (SPC) started work together. Funding was provided by the European Union’s Plant Protection in the Pacific (PPP) project, managed by SPC. As a first step, a major biotechnology upgrade at the Ministry’s Koronivia Research Station and at the University of the South Pacific was made. Biotechnology, including the DNA analyses used in forensic police work, has now unlocked the door to understanding kava dieback. New breakthroughs have been made that provide the foundation for an integrated dieback disease management package. It will be based on a combination of simple actions growers can take that reduce the sources of the virus and suppress plant to plant spread - no pesticides involved, and all in an agroforestry context. This package takes advantage of two principal weaknesses of CMV: The virus is unable to completely infect and spread through all parts of kava plants It is easily lost from the mouthparts of the insects that spread it when they feed on non hosts. Details are now being finalised, but the package is basically: 1. Start with healthy plants Growers must only use uninfected planting material. In the short term, this can be achieved to some extent by very carefully advised selection from what is currently available in the field. In the longer term, virus tested kava planting material should be made available, hopefully by commercial tissue culturing. 2. Slow the spread of the disease from plant to plant when it appears If a kid has flu virus, the best thing to do is keep him or her out of the classroom, to prevent spread to the other kids. As plant diseases are like human ones, growers were first advised to destroy all diseased plants, before they infect their neighbours. This was never widely adopted because each plant is of high value and growers know that some new growth follows stem rot. Since then, it has been discovered, using biotechnology, that many symptomless stems and new growth on infected plants are virus-free. This implies that vigilant removal of only kava stems showing early signs of disease could be an effective policy. How well this practice works is now being tested by both scientists and growers in Fiji and Tonga. 3. Smart cropping: use natural barriers to reduce the spread of the disease Kava is best intercropped in early stages of growth and planting non-hosts between kava plants will reduce within plot spread of CMV. Studies to determine which key kava intercrops and weeds are alternative hosts for the dieback causing strain(s) of CMV are progressing well and definitive advice for growers is imminent. 4. Choose a good planting location Dieback is much less of a problem when grown in the traditional way. That is in small and isolated plantings grown amongst natural vegetation and below a tree canopy. This is because many of these plants are not hosts to the disease. Because of this, they act as a buffer zone, protecting the kava from incoming insects carrying CMV. The more separated the plantings are from each other, the better this works. Kava also seems to be less likely to develop dieback when CMV is around when it is growing vigorously. For this reason, growers should only plant in the right kinds of soils: well drained, fertile and high in organic matter. * Comments: Post a Comment	Archive October 2002 November 2002 December 2002 January 2003 February 2003 March 2003 April 2003 May 2003 June 2003 July 2003 August 2003 September 2003 October 2003 November 2003 December 2003 January 2004 February 2004 March 2004 April 2004 May 2004 June 2004 July 2004 August 2004 September 2004 October 2004 November 2004 December 2004 January 2005 February 2005 March 2005 April 2005 May 2005 June 2005 July 2005 August 2005 September 2005 October 2005 November 2005 December 2005 January 2006 February 2006 March 2006 April 2006 May 2006 June 2006 July 2006 August 2006 September 2006 October 2006 November 2006 December 2006 January 2007 February 2007 March 2007 April 2007 May 2007 June 2007 July 2007 August 2007 September 2007 October 2007 November 2007 December 2007 January 2008 February 2008 March 2008 April 2008 May 2008 June 2008 July 2008 August 2008 September 2008 October 2008 November 2008 December 2008 January 2009 February 2009 March 2009 April 2009 May 2009 June 2009 July 2009 August 2009 September 2009 October 2009 November 2009 January 2010 RSS Feed Alternative feed Contact Tevita Something new: Agrobiodiversity Weblog: For discussions of conservation and sustainable use of the genetic resources of crops, livestock and their wild relatives. 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