Scientists have raised alarms over the potential destruction of blueberries by a rapidly spreading fungus, with the disease threatening crops worldwide.
The disease, caused by two different strains of fungi, appears as a white powdery mildew on blueberry plants, which reduces crop yields and increases reliance on fungicides.
Erysiphe vaccinii, the fungus responsible, has been spreading globally over the last 12 years.
One strain has reached China, the world’s largest producer of blueberries, as well as Mexico and California, while another has spread to Morocco, Peru, and Portugal.
An assistant professor at North Carolina State, Michael Bradshaw, remarked, “This is a hard organism to control. If you’re sending plant material across the world, you’re likely spreading this fungus with it.”
The research also discovered that the fungus found outside the United States seems to reproduce only asexually. In contrast, the version in the U.S. reproduces both sexually and asexually.
The study estimates that the disease could cost the global blueberry industry between $47 million and $530 million annually, as more than four billion pounds of blueberries are sold worldwide each year.
Initially believed to have originated in the eastern U.S., the disease has remained mostly confined to that region, although small outbreaks have been reported in southern California.
The research also issued a warning to the Pacific Northwest, where the rainy climate could provide ideal conditions for the mildew to invade crops that have so far been unaffected.
The powdery mildew envelops host plants parasitically, depleting their nutrients and hindering photosynthesis while keeping the host plant alive.
However, the new discovery offers hope for better management of the disease by making its identification easier.
To help manage the spread, researchers at North Carolina State have developed a database that both scientists and farmers can use to track and report disease cases.
“This platform allows growers to enter their data and learn which specific strain is in their fields,” said Bradshaw. “That’s important because understanding the genetics can warn farmers about which strain they have, whether it is resistant to fungicides, and how the disease is spreading, as well as the virulence of particular strains.”
Though primarily identified in blueberries, the fungus has also been found to affect wheat, hops, grapes, and strawberries.
Blueberries, native to America, are believed to have been one of the first edible fruits discovered by native people after the last ice age. Beyond being eaten fresh, Native Americans incorporated blueberries into dishes such as soups, stews, preserves, and puddings.
The fruit also played a role in traditional medicine, with its roots, stems, leaves, and flowers being used for various remedies.
Known today as the highbush variety, blueberries originally grew across the arctic plains and extended down through what is now the United States, Mexico, and parts of South America.
While this information is just emerging, the study at the University of North Carolina includes a specimen collected over 150 years ago by the North American herbarium.
