Rubber plantations advised to be alert on fast-spreading leaf disease

The rubber plantations have been advised to be vigilant and be on the active lookout for any signs of the leaf disease Pestalotiopsis, a threat that could impact the 
industry output.

With the rubber plantations in Malaysia, India, Thailand, Cameroon and Papua New Guinea already witnessing a considerable yield loss due to the fungus, the Colombo Rubber Traders’ Association (CRTA) asserted that the local stakeholders must be on full alert.

“All stakeholders are requested to be vigilant about this threat to the rubber plantation and they are strongly advised to get the assistance of the scientists of the RRI in any emergency,” the CTRA said in a statement yesterday.

The Rubber Research Institute (RRI) would extend assistance to plantations to correctly identify the Pestalotiopsis-affected trees from the trees defoliated due to wintering, it added.
The association warned the disease may reach epidemic proportions in the coming monsoon period, starting from mid-April.

According to the CTRA, the ‘leaf fall disease’ can be easily identified, as it produces circular patches on the affected leaves.

“Sometimes these lesions coalesce to form necrotic areas on leaf surfaces and causing the fall of leaves. This unusual leaf fall should not be mistaken as late wintering and neglected,” the CTRA cautioned.

As no resistant clone to this disease has been identified to-date, the association said application of fungicides is the only means of managing the spread.

It highlighted that haphazard application of fungicides is of no use to control the disease and chemical spraying should be done at early stages.

However, the CTRA said that proper protocol for fungicides spraying has not been developed yet. 

Trials are being carried out to use drones for the application from a height of five meters above the canopy of trees, to introduce an economical and effective chemical control system.

Pestalotiopsis was considered a mild pathogen until recent times. The most recent outbreak was in 2019, where the epidemic affected the plantations in the Kalutara, Ratnapura and Galle districts.

High humidity favours the spread of the disease, causing defoliation and a considerable yield loss and ultimately the death of the tree.