Disease threatens Pacific coconut gene bank | Pacific Beat

Disease threatens Pacific coconut gene bank

Disease threatens Pacific coconut gene bank

Updated 14 November 2012, 10:46 AEDT

The international collection of the South Pacific's coconut palms is under threat from a disease outbreak close to the gene bank in Papua New Guinea.

Bogia Coconut Syndrome is threatening the survival of a gene bank of region's most important tree.

The gene bank holds 32,000 trees representing almost 60 varieties of coconut.

Dr Richard Markham is a research programme manager for the Australian Centre for International Agricultural Research.

He is one of the people working to save the gene bank, and says the current threat to it is serious.

Presenter: Geraldine Coutts

Speaker: Dr Richard Markham, research programme manager, Australian Centre for International Agricultural Research


MARKHAM: This is the best collection of coconuts in this whole region by far and coconuts are most important probably for smallholders throughout the Pacific Islands. So at one level it's a very serious threat. On the otherhand, I mean we have to take a measured response that this disease has been around for quite a long time. We've known about it for approximately 20 years. It hasn't moved very fast. It's been at this site called Bogia, about 50 kilometres from the collection for quite a long time.
What's caused a certain amount of anxiety in the research involvement community is that just recently, a couple of years ago, it's jumped to a village very close to the town of Madang. Now this isn't actually that much closer to the gene bank. It's about 35 kilometres on the otherside of the gene bank, so it's actually jumped past the gene bank. But what worries us about this new outbreak is that it's very close to the commercial centre of Madang. It's only about five kilometres from Madang and that's a really busy market centre with lots of agricultural activity. And we're worried about the disease then spreading in normal, if you like, normal commercial traffic from Madang, more widely in Papua New Guinea.
COUTTS: Well, the bacteria, better known as Lethal Yellowing Disease or similar to or distinct from the Lethal Yellowing Disease. Is it controlled, can you eradicate it and save this gene bank?
MARKHAM: Well, we couldn't eradicate the disease. I think it's really important to say that we believe that Bogia Coconut Syndrome is different from Lethal Yellowing. 
Lethal Yellowing is a disease that's also caused by one of these special bacteria called phytoplasma. This has really caused severe problems in the Caribbean Islands, in Central America. It's also been very destructive in Africa, spreading steadily, and really knocking out large swaths of coconut production.
Now this one in Madang, the molecular biologist tell us it's a similar phytoplasma, but the key is we don't know what insect transmits it. These things are not casually transmitted by cane knife cuts and things like that. They have to be transmitted by an insect that's very closely adapted to the disease and for the Papua New Guinea one, we don't know what the insect vector is, the insect that transmits it and that's what we're focusing on at the moment, because the rate at which something spreads depends critically on what the insect is and what it's behaviour is.
COUTTS: Well, PNG ironically was selected for the site for the gene bank in the 1990s as the country was relatively free of coconut pests and diseases. So does it suggest that this one's been brought in?
MARKHAM: No, as I say, we believe that this one's been there for a good 20 or more years. 
What tends to happen, these diseases are quite widespread in different palms, they're not very well known or understood, but we suspect that it probably came from a wild palm species and possibly transmitted by the insects associated by it.
And that's another of the things that concerns us about the new outbreak near Madang. For the previous 20 years, this disease seems to have been entirely in coconut palms, whereas the new outbreak in Madang is also affecting Areca Nut Palms and also sago and is also affecting really an unrelated plant which is the banana, and all these palms are actually economically important for people in Papua New Guinea, they're part of their livelihoods and we're facing really a dual threat. One is to the livelihoods of smallholders and then there's this other distinct threat to the gene bank, so we've really got to tackle both aspects of the problem.
COUTTS: Well, that's a tricky one, isn't it, because I'm presuming it's contagious and there are a lot of trees. So how do you go about fixing it, because you've got to isolate them within the gene bank and you can't take them outside presumably to quarantine them there? So how do you go about the cleanup?
MARKHAM: What's happening is they've put a little bit of the cote de santetare around the affected village, which is called Foran, which is nearer to Madang, than to the gene bank. You mentioned the word contagious. I mean that implies that the disease is easily transmitted. What I was saying about this one is it's actually not that easily transmitted. It has to have this insect carry it. So really basically what we need to do is to find out what the insect is. It's obviously not flying or migrating very vigorously or the disease would be all over the place. It seems to just travel locally from an outbreak and we believe that this jump that happened from Bogia to Foran, Madang area, was by we think we've identified the people who carried it. They carried it infected seed, coconuts from Bogia to Foran. So that's the kind of movement we have to stop. We're trying to discourage people from moving coconuts and that's how we'll protect the collection and at the moment, as I say, it's still a good 35 kilometres from the collection itself. So what we do is the normal clean movement procedures. People can't bring plant material onto the station without inspection and so on, so we'll continue the normal sort of routine measures to protect the gene bank. But I think in the long term, the important thing about a gene bank is that it should be able to receive and then also disseminate plants and materials for people to us in development activities and so that's why we're talking actually about trying to duplicate the collection which in fact means going out to the different islands and collecting some of these key varieties all over again and setting them up in safe places elsewhere.

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