Managing viral diseases in black pepper
M.J. PRABU
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The infestation is severe in nurseries as the seedlings are closely placed
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DISEASE SYMPTOMS: Affected vines exhibit stunted growth and the leaves have mosaic like patterns on them. — Photo: IISR
VIRAL DISEASE of black pepper, which is also known as stunted disease, is prevalent in major black pepper cultivating regions of Karnataka and Kerala.
Affected leaves exhibit mosaic like patterns and sickle shaped appearance. In advanced stages of infection the internodes of vines become abnormally short, leading to stunted growth.
Viruses responsible
Investigations carried out at the Indian Institute of Spices Research (IISR), Calicut, have proved that two viruses namely, Cucumber mosaic virus (CMV) and Piper yellow mottle virus (PYMV) are responsible for the spread of the infection.
"Both these viruses spread mainly through infected stem cuttings. When infected cuttings are used as source of planting material, the new plants also get infected," said Dr. A. Ishwara Bhat, senior scientist of the institute.
"Adequate care should also be taken to plant healthy, virus-free cuttings especially in new areas where the incidence of the disease is not observed."
"The proven method to control these infestations would be to plant virus-free cuttings," he said. Once a healthy, virus-free plant is identified, it must be kept under observation in virus-free and insect-proof conditions, according to him.
"Cuttings or tissue culture raised plants obtained from these virus-free stocks are then developed on a large scale where re-infection is minimal or absent.
These stocks are then used for commercial planting," explained Dr. Bhat.
Detection methods
"The institute has developed its own advanced virus detection methods for the detecting both these viruses affecting black pepper," said Dr. S. Devasahayam, principal scientist of the institute. "These methods are useful for detection of virus infection in plants that do not show any visible symptoms," he said.
"Once healthy plants are identified by these methods, they can be protected and used for further multiplication through healthy cuttings," said Dr. Devasahayam.
Preventing infection
Removal of infected plants at periodical intervals and replanting with healthy ones should be resorted to, to prevent the spread of this infection, according to him.
"Infected stem cuttings, insects such as aphids and mealy bugs also transmit the disease to healthy plants both in the field and in the nurseries," said Dr. Bhat.
The infestation is severe in nurseries as the seedlings are closely placed, according to him.
Pest management
"Spraying insecticides such as 5 per cent dimethoate or monocrotophos solution diluted in one litre of water may help in the control of the infestation in the nurseries," Dr. Bhat explained.
For more information readers may contact the Head, Division of Crop Protection, Indian Institute of Spices Research (IISR), Marikunnu P.O, Kozhikkode - 673 012 Kerala, Phone: 0495 2731410 (ext) 200, email: ishwarabhat@iisr.org
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