New disease threatens rubber plantations in Sri Lanka

A new disease is said to be threatening rubber plantations in Sri Lanka.

The Colombo Rubber Traders’ Association (CRTA) said that the pestalotiopsis leaf disease of rubber is a new threat to the rubber plantation industry.

Pestalotiopsis leaf fall caused by the fungal pathogen pestalotiopsis has now become a grave threat to the sustainability of the rubber plantation industry in Sri Lanka.

Though this fungus has been reported far back as the early 20th century in the country, it was considered as a mild pathogen until recent times.

It reached epidemic proportions during the monsoon period of 2019 affecting plantations in the Kalutara, Ratnapura and Galle Districts.

CRTA said that almost all clones are susceptible for this disease unlike the corynespora leaf disease which was affecting the clone RRIC 103 at the start and later spread to few other clones grown in the country as well.

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

Unlike in the case of corynespora leaf disease affecting young leaves at the apple green stage soon after wintering period, this new disease affects even mature leaves in the last quarter of the year.

Further RRI scientists have observed the higher tendency of pestalotiopsis fungus to attack leaves already slightly affected by glyosporium affected leaves.

The disease can be easily identified as it produces circular patches on affected leaves.

Presently the other countries affected by this leaf disease are Malaysia, India, Thailand, Cameroon and Papua New Guinea.

In these countries, the disease is spreading at an alarming rate causing a considerable yield loss.

As no resistant clone to this disease is identified to date, the only hope in managing the disease is by the use of fungicides.

The disease may reach epidemic proportions during the monsoon period of this year starting from mid-April and hence all stakeholders are requested to be vigilant about this threat to the rubber plantation. (Colombo Gazette)

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