Thursday, November 24, 2011

United Nations warns of virus attack on cassava in PNG


UNITED Nations scientists are warning that a virus is attacking the cassava plant, a staple food in Papua New Guinea which is also gaining commercial momentum in the eastern coastal region of Central province, The National reports.
The virus is currently rampant in parts of Africa where it is nearing an epidemic but in PNG authorities have indicate that they were aware of its spread there and were taking measures to prevent its introduction to PNG.
It is known as the cassava brown streak disease (CBSD).
Cassava is one of the world’s most-important crops providing up to a third of the calorie intake for many people not only in Africa but also in PNG because it does well on poor soils with low rainfall.
According to BBC World Service last week, the Food and Agriculture Organisation (FAO) of the UN said the African situation was urgent and was calling for an increase in funding for surveillance.
CBSD shows up late in the production cycle as when harvesting.
Farmers may think their affected crop is healthy only to find when the tuber is harvested that the crop is bad.
The symptoms can be recognised on leaves, stem and storage roots of cassava plants.
On leaves it appears to as patches of yellow areas mixed with normal green colour.
The yellow patches are more prominent on mature leaves than on young leaves. The damage leaves do not become distorted in shape.
On the stems, the disease appears as dark brown streaks with dead spots on leaf scars.
These streaks are most prominent on upper, green portions of the stems.
The disease plants may show shoot tip die-back.
Cassava brown streak distorts the shape of the storage roots and may cause cracks and discolourisation in the storage roots.
An officer with Changhae Tapioka (PNG) Ltd, the South Korean firm initiating a multi-million kina cassava bio-fuel project in Central, said this week they were aware of CBSD.
He said the most common way this disease was spread was by planting of stem cuttings from diseased plants.
The virus is also believed to be spread by insects.
 It is not known to have attacked other crops.
The disease can be managed by controlling planting materials in a well-kept nursery thereby increasing high chance of healthy planting material.
Another method is to use integrated pest management practices which include site selection, soil improvement practices, selection of appropriate varieties and planting materials.
The best practice to manage the spread of disease is to burn all infected crops. Chemicals and pesticides can be used but in large quantity they can affect the surrounding environment.
The officers said, not all hybrids are effective as control measures and more research is needed in this area.
In preventing cassava viruses reaching PNG, strict quarantine measures must be taken.
The National Agriculture Quarantine Inspection Authority (NAQIA) is responsible for all imported plant materials.
The National Agriculture Research Institute (NARI) is responsible for all research into plants diseases in PNG.
These are important institutions in PNG, including Department of Environment and Conservation, which are responsible for enforcing good management practices of developers.
The officer said that at the Changhae Tapioka (PNG) Ltd cassava plantation, pest and disease spread was managed mainly through application of chemical, biological and burning.
Imported varieties from Indonesia are monitored closely for first signs of disease and pest.
He said all imported varieties of cassava were to produce high starch content as compared to our local varieties.
All imported varieties are restricted to the plantation and are not for distribution to locals.
The company wishes to only promote local varieties through its out-growers programme.
There are nine varieties of cassava, the local varieties, as well as the imported.
The company has been working closely with NAQIA and NARI for its agro-business in PNG.
In the future the company will look into developing and exploiting virus resistance and effective methods of phytosanitation (removing infected or infested plants).
The common diseases of cassava are cassava mosaic disease, cassava bacterial blight, cassava anthracnose disease, cassava bud necrosis, and root rots.
Some of these disease attacked leaves and steams of cassava plants while others attacked the storage roots.
Common leaf and stem diseases include cassava mosaic disease, cassava bacterial blight.
Cassava anthracnose disease, cassava bud necrosis and brown steak disease affect the storage roots.
According to BBC, the FAO found that none of the varieties of cassava being distributed to farmers in Africa appeared to be resistant to the CBSD virus.
FAO said that like many crops it was threatened by a number of pests and diseases that hindered its production. Viral infections have periodically wiped out the crop in some regions leading to famine, it added.
The scientists said CBSD was on the verge of becoming an epidemic. It first appeared in Uganda in 2006 but in the past few months had been found in Burundi and the Democratic Republic of Congo for the first time, BBC reported.
The FAO scientists say they are in a race against time with this particular strain of virus. They are calling for a rapid increase in funding to improve surveillance. They also want to improve training for farmers and they want to ban the distribution of infected plants between districts.
Some eight varieties of the crop are under development by the International Institute of Tropical Agriculture which show some level of resistance to CBSD.
It is hoped that these varieties could be made widely available within two years.

1 comment:

  1. Matthew 24:7 For nation shall rise against nation, and kingdom against kingdom: and there shall be famines, and pestilences, and earthquakes, in divers places.