Farmers have reported more cases of bud rot and crown rot diseases prevalent in arecanut plantations in Puttur and Bantwal taluks in addition to such incidences reported from Kadaba and Moodbidri taluks in Dakshina Kannada a few days ago.
A scientist at the Vitla Regional Station of the Central Plantation Crops Research Institute (CPCRI) Bhavishya told The Hindu that after media threw light on the diseases in an arecanut garden at Perabe village in Kadaba taluk, more farmers from Puttur and Bantwal have informed him about the diseases prevailing in their plantations.
The scientist, who is among a three-member team of CPCRI scientists that visited one of the affected plantations in Kadaba taluk on Tuesday last, said that the diseases, including fruit rot, could be prevalent in more number of plantations. But farmers have not reported them yet.
He said that unless rain continues, the chances of the diseases spreading to a vast track of plantations are less. But it will depend on the intensity of rainfall during September.
The scientist said that this year these diseases have been spotted early. It might be because certain tracks have been experiencing rainfall since this April.
Fruit rot disease/Mahali/Koleroga caused by the pathogen Phytophthora meadii is the primary enemy of arecanut in high rainfall condition. This year, the incidence of fruit rot is observed in many arecanut gardens; however, the intensity has not been high, he said and added that in case of fruit rot only crop is lost, while the other two diseases can wipe out palms.
The pathogen also affects crown and bud of arecanut palm to cause crown rot and bud rot, respectively.
“The pathogen is present in infected bunches/plant parts for many years. It becomes active under favourable conditions. Hence, phyto-sanitation (removal of the infected plant part or whole plant) followed by spraying Bordeaux mixture (1%) on crown or bud region of the affected and neighbouring palms is very important to prevent further spread,” Mr. Bhavishya said.
“Metalaxyl + Mancozeb (2g per litre) can be sprayed immediately on the crown and bud region of infected and neighbouring palms and then, while spraying on bunches, applying Bordeaux mixture (1%). Drenching the crown of affected palms with 1% Bordeaux mixture and smearing with 10% Bordeaux paste after removal of affected tissues is effective in saving bud rot affected palms. Regular monitoring of treated palms is needed for checking further advancement of symptoms,” said scientist R. Thava Prakasa Pandian, another member of the team.
In newly planted gardens and secondary nurseries, the fungus causes collar rot. Recently, it was observed in many arecanut growing areas, especially in water logged and poorly drained fields. Infection by the pathogen enters through collar region and it may lead to rotting of the infected region and the entire seedling may collapse. Whereas, infection through roots may result in seedling wilt. Providing good drainage, phytosanitation, soil drenching with 0.2% Copper oxychloride or 1% Bordeaux mixture will reduce the disease incidence.
Undecomposed wastes shouldn’t be applied near the collar region. Importantly, the measures should be taken up in the initial stage, the two scientists, with another team member scientist Nagaraja N.R., said.
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