WASHINGTON—Neofusicoccum ribis, one of more than 90 fungi in the genus Fusicoccum, is causing leaf fall disease among Hevea brasiliensis trees in Indonesia.
How much of a problem this is creating, however, depends on whom you ask.
"The future of the Indonesian Hevea remains at risk," said Kavickumar s/o Muruganathan, vice president, environment, health & safety at Halcyon Agri Corp. Ltd., in an October 2018 article titled, "The Sorry State of the Indonesian Hevea."
"Vast swathes of rubber trees have already been lost to the Fusicoccum pathogen, and more losses are due until a concrete solution is found to combat this dilapidating disease," Muruganathan wrote.
The March 2019 issue of Natural Rubber Trends & Statistics, the monthly publication of the Association of Natural Rubber Producing Countries, suggested the Fusicoccum fungus was a problem affecting NR supplies in Indonesia.
In that issue, ANRPC Secretary General Nguyen Ngoc Bich noted that world NR production fell 5.2 percent in the first quarter of 2019, with sagging prices and a long wintering season partly to blame.
"The new leaf fall disease in South Sumatra might also have contributed to the drop," Nguyen wrote.
But other sources within the NR industry said they doubted that the Fusicoccum fungus was spreading quickly or having much of an effect.
"Yes, there is a leaf blight in Indonesia, but it's been contained in the area where it is," said one industry source who asked to remain anonymous.
The information available on Indonesian leaf fall disease in the West is fragmentary and often contradictory, according to Alan L. Grant Polymer.
According to the estimate now circulating, about 100,000 hectares (slightly less than 250,000 acres) of NR-growing land in Indonesia has been affected by the fungus, said the Norfolk, Va.-based rubber supplier.
"This represents 3 percent of Indonesia's mature growing area, meaning impact on Indonesian production is only 3 percent," the company said. "(But) other sources are claiming Indonesian production is down 10-30 percent."