Bud rot and crown rot diseases along with fruit rot (mahali or kole roga) disease have resurfaced in some arecanut plantations in Dakshina Kannada.
At present, the diseases have been reported from Kadaba and Moodbidri taluks.
A three-member team of scientists from the Vitla regional station of the Central Plantation Crops Research Institute (CPCRI) visited one of the affected plantations at Idala under Perabe village in Kadaba taluk on Tuesday to study and recommend disease control measures to the plantation owner Suresh.
According to CPCRI, the three diseases are caused by the Phytophthora fungus. It attacks adult areca palms during south-west monsoon causing fruit rot (mahali or kole roga). The fungus also attacks the growing bud and the crown resulting in bud and crown rots, respectively.
“The later two diseases (bud and crown rots) are fatal if they are not noticed and treated in time,” one of the team members scientist Bhavishya told The Hindu .
In case of fruit rot (mahali or kole roga), only the crop is lost. Whereas in case of severe bud and crown rots, the palm itself is lost. Hence, farmers should notice early symptoms, when leaves and the outermost leaf sheath turn yellow, of the latter two diseases carefully and report them to farm scientists and take disease control measures suggested, he said.
The scientist recalled that an arecanut grower in Bantwal taluk lost about 70 % of palms in his plantation about four years ago to bud and crown rots as he either failed to notice the symptoms early or had ignored them till the infection became severe.
Mr. Bhavishya said that about two weeks ago, two more farmers from Moodbidri area contacted CPCRI seeking disease control measures.
He said that in case of the plantation in Perabe village, the symptoms of the diseases were noticed in 2018. But the farmer concerned did not take any disease control measure. Now, it has resurfaced to the full extent. The farmer told the team that the diseases were noticed this July itself.
The scientist said that in many plantations, the fungus may remain in dormant state. It becomes active when weather and atmosphere becomes conducive.
The other team members which visited Perabe comprised scientists Nagaraja N.R. and Thawa Prakas Pandian.
General Secretary of All India Areca Growers Association Puttur Mahesh Puchchappady, who accompanied the team, said that there are every chance of many farmers not reporting the symptoms of bud and crown rots to farm scientists or the Horticulture Department. They should report the symptoms to prevent the spread of the diseases to a vast track of plantations in the region.
The diseases explained
Fruit rot disease is characterised by rotting and heavy shedding of immature nuts.
In case of bud rot, the fungus can attack the bunch stalk or the tender portion of the stem. It can enter directly through the outer leaf sheath into the tender growing point leading to crown rot.
Bud rot and crown rot can occur frequently in fruit rot-affected palms either independently or following severe fruit rot.
Bud rot is characterised by rotting of growing bud and the surrounding tissues. The initial visible symptom is yellowing of the spindle leaf. The affected spindle loses its natural green colour and in the advanced stages, turn to yellow and can be drawn out with a gentle pull. When the infection becomes severe and spreads to adjacent leaves, they turn yellow, droop and drop off ultimately leaving a bare stem.
In case of crown rot, infection initiates from the base of outermost leaf sheath or from the stalk ends of infected areca bunches or developing inflorescence and slowly spread to the internal tissues of the stem.
The first visible symptom is yellowing of the outermost leaf sheath. When the infection becomes severe, internal tissues of the crown rots, leaves turn yellow and finally, the palm dies.
( Source: Arecanut, book published by the Central Plantation Crops Research Institute, Kasaragod, Kerala .)
