Basil Downy Mildew damaging crops across Oahu

Basil Downy Mildew
Basil Downy Mildew
Janice Uchida
Janice Uchida

By Lisa Kubota - bio | email

HONOLULU (HawaiiNewsNow) - The recent rainy and cool weather has helped to trigger a new threat to farmers. Basil downy mildew is spreading through Oahu's valuable crop. The problem was first spotted by basil growers in Waianae last month. Now it has spread to locations in Kahuku, Kunia and Diamond Head.

Plant pathologist Janice Uchida of UH Manoa's College of Tropical Agriculture and Human Resources diagnoses new diseases. She said basil downy mildew isn't toxic to humans, but it can cause widespread crop damage.

"This is bad. It'll spread miles. It just blows in the wind," explained Uchida.

Researchers aren't sure how the mildew ended up in Hawaii. It could have arrived through contaminated seeds or shipments of fresh basil into the state. The recent wet weather contributed to the infestation.

"The amount of rainfall in Waianae is amazing, right. Plus, it has been cold. So this fungus likes it wet and cold," said Uchida.

Winter is the peak season for Hawaii's $6.8 million basil industry. The crop is sold statewide and exported to the mainland and Canada. Over at the farmers market in Manoa, Keo Oulayrack was concerned the mildew could contaminate her family's plants.

"We do have basil ourselves so we kind of got worried because our customer do buy a lot of sweet basil. And my sister, she does have restaurants that she wholesales to," said Oulayrack of Souane Farms.

Basil downy mildew produces black or brown spores on the undersides of leaves, followed by yellow, then dark discoloration. Farmers are being urged to prune back their plants and control the fungus with chemicals.

"They just take off the top, so all of this is still left there full of the fungus, and so it's a bad situation because when you spray the fungicide on the pathogen you're likely to get a mutation."

Authorities are now hoping to keep the fungus from infecting crops on the neighbor islands.

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