Rubber plantations in disease crisis
Sri Lanka’s rubber plantations have been hit by a fast spreading disease that could cause about 10 per cent crop loss while growers are awaiting the recommended pesticides to be imported that could be expensive to apply considering the drone equipment required to do so.
The pesticides Hexachonozole and Carbendazin, though available in December, are currently not available in the market, Rubber Research Institute Pathologist Dr. Sarojini Fernando told the Business Times. The current foreign exchange crisis could be a reason for the lack of availability of the required chemicals.
She explained that estimates made by scientists have found that the loss can be around 10- 20 per cent at the international level and it could go up to about 40 per cent but in Sri Lanka it is up to about 10 per cent.
In 2019 the rubber plantations were identified as having Pestalotiotsis or the pesta disease but scientists found another disease last November, a circular spot leaf disease identified as Colletotrichum.
Dr. Fernando explained that this is not a disease new to Sri Lanka but that all other rubber producing countries like Malaysia, India, China and Indonesia were also experiencing this disease and the most recent outbreak was from Vietnam.
Three new pathogens had been identified and research
scientists have found that the loss can be around 10-20 per cent at the international level and it could go up to about 40 per cent but in Sri Lanka it is up to about 10 per cent.
work is ongoing and recommendations have been provided to stop further spread of the disease and minimise economic loss.
The chemicals are required by May when re- foliation or new flushes of leaves appear which is also when the new disease can be observed and it can be applied when the leaves are mature, she noted.
Dr. Fernando also pointed out that it was important to apply not just the pesticides but also carry out all other agronomic practices to ensure the effectiveness of the application of the chemicals on the plant.
She also noted that this disease was most prevalent in wet areas and that though they had initially thought the pesta disease could kill the crop it was not so.
Drone experiments have been started by one company in a bid to find out the flying rate and application rate and streamline the application, which can then be used to educate the growers.
No blanket recommendations could be made, Dr. Fernando said noting that in large estates with a canopy of 40 feet height mist blowers were used and that small growers could be assisted by the Rubber Department.
Dr. Fernando explained that government funds amounting to Rs.50 million have been allocated for research into this disease over a period of five years as a development and research project. Research has so far been carried out for over one year.
It was pointed out that the excessive tapping of the plant last year could also adversely impact the plant and as such proper agricultural practices should be carried out like fertiliser, weedicides and other adequate nutrients.
Last year there had been a slight drop in overall production of about 10 per cent but high prices were recorded as a result of the shortage in the global market.
Smallholders that comprise about 65 per cent of production have gone into excessive tapping as they had suffered for a long time but this can have a long term adverse impact, it was noted.
Growers point out that they had found the infection spread in almost every rubber growing area like Hanwella, Nivithigala and Kalutara.
In 2021 the disease had spread to approximately 40,000 H of rubber plantations, it was noted.
A Planters Association Committee Member pointed out using drones can be implemented if they are economical as the cost of this equipment was between Rs.3-5 million.
It was pointed out that the effectiveness of the chemicals could be observed when the next season of rains should take place.
Moreover the chemicals available in the agrochemical shops have now become more expensive as prices have increased by about 100-200 per cent.