Mystery ‘dwarfing’ disease

In News: Scientists track cause of mystery paddy dwarfing in Punjab and Haryana

• Scientists at the Indian Agricultural Research Institute (IARI),collected samples of plants from farmers’ fields – which showed symptoms of stunting and yellowing and have undertaken electron microscopy analysis and DNA isolation through PCR (polymerase chain reaction) technique.
• Agriculture scientists have narrowed down the cause of a mystery disease causing “dwarfing” of rice plants in Punjab and Haryana to either grassy stunt virus or phytoplasma bacteria.
• The vector responsible for their transmission is the brown plant hopper, an insect pest that sucks sap from the stems and leaves of rice plants.
• Preliminary laboratory analysis indicates the “phytoreovirus” or rice grassy stunt virus as the source of infection.
• This virus, which induces stunting and yellowing of rice plants, is transmitted by brown plant hopper.
• The second possible source is phytoplasma, a bacterial pathogen that is spread by both brown plant hopper and green leaf hopper sucking insect pests.

Many farmers in Punjab, Haryana and even parts of western Uttar Pradesh and Uttarakhand have, for the past fortnight or more, been reporting stunting of paddy plants in their fields.

Such stunting has taken place typically 30-35 days after transplanting or direct seeding of rice. Initially, all plants register uniform growth. But at a later stage, some stop growing while others continue.

The proportion of dwarfed plants has been generally reported at 10 to 25 per cent, even exceeding 40 per cent in some cases.

Source: Indian Express