Source: CFFN – Nov 11 2006
Reported By Dr Pramod Dhakal for Canada Forum for Nepal
Nov 11 2006 – Ottawa, Canada: Once again a hope has emerged for the great oranges of Pokhara Valley. This valley was extremely suited for growing great oranges because of its climatic conditions and soil properties, with due respect for other districts like Bhojpur, Dhankuta and more. However, a mysterious disease hit Nepal’s orange farming in such a fury that the oranges were essentially wiped out from the Pokhara Valley and many parts of Nepal. Nepal today relies on imported oranges to satisfy internal demands for consumption. The culprit was a disease later named as Citrus Greening Disease but it has eluded the scientists who wanted to conquer this to revive the orange farms of Nepal once again. That was until now, but today a new hope has emerged with the scientific discovery of a Nepalese agricultural scientist working in Canada.
Great citrus fruits like oranges, grapefruits, lemons, and limes are excellent source of both vitamin C and cash for Nepalese farmers. Not only they are full of fragrances, flavors and juice but they test sweet long after harvest. Their evergreen trees can be cultivated using varieties of ways, such as seed budding and grafting. However, these great trees are very susceptible to many diseases and pests. Diseases like Citrus Greening Disease, Citrus Canker, Citrus Variegated Chorosis and Tristeza are specifically bad. The Citrus Greening Disease in particular is one of the most devastating diseases causing extensive damage to citrus trees.
The dark side of these diseases is that they affect the fruit production, and consequently the harvest, but they do not show their devastating face for the first three to five years while the farmers are raising these trees with great expectations. This disease is detected after the tree bears the fruit, but by then it is too late for the farmer.
First discovered in 1968 at Pokhara, this disease has caused sharp decline in the production of citrus fruit in Nepal. Since then, Nepal has not been able to meet the internal citrus fruit demand. Nepalese government has launched many programs, namely National Citrus Development Program, Junar Development Project, Hill Fruit Development Program in the last several years to control this disease. Nevertheless, this has had little effect on the local production of the fruits.
Although the disease first manifests itself in the form of small and lopsided fruits that remain green in shaded side even when mature, the true culprit is a Gram-negative bacterium that grows in the tissue of citrus plants and causes the tree to die. No one has been able to culture the bacteria so far, hence there is no cure. Only way to stop this disease is to replace infected trees with brand new uninfected plantlets. But the farmers already incur huge loss and can’t earn money from their mature trees.
To complicate the matter further, those “disease free” plants are grown inside a laboratory, and are expensive and unaffordable to most farmers. Also, the disease-free tree has only a 25% survival rate on the field. Clearly, this is a highly inconvenient way of cultivating citrus fruits.
A Nepalese Canadian scientist Dr. Bhaju K Tamot has come up with an alternate method, which makes it possible for an early detection of this disease. This means that the farmer can now minimize the loss on his investment, and can quickly replace the disease plants with a seedling from his stock.
The detection method of Dr. Tamot involves a molecular technique called DNA Amplification Fingerprinting which was developed in collaboration with the University of Tennessee, and funded by National Science Foundation of USA. By using this technique, the infected citrus plants can be detected at any stage by analyzing a small part of the leaf vein. Farmers can reliably and affordably get the diagnosis by simply mailing a leaf by mail to the nearest testing facility. They could keep the farms disease free by annually sampling their trees and testing. With his invention, Dr. Tamot is confident that an “orange revolution” is in the immediate horizon for Nepalese citrus farmers.
Source: Dr Bahju Tamot, University of Guelph, Ontario, Canada – 2006 Nov 11