Rust confirmed in java plums

WAILUA — Rust has been confirmed in java plum tree samples from the Wailua Homesteads area.

Confirmed on Wednesday by Janice Uchida, a mycologist at UH Manoa, Department of Plant and Environmental Protection Sciences at the University of Hawaii, the tree disease killed a swath of rose apple, or mountain apple, trees statewide about 10 years ago and has about 400 plant hosts — most commonly the myrtle family.

It’s known formally as the Austropuccinia rust (formerly called Puccinia rust), is commonly known as “guava rust,” and it doesn’t target ohia trees, like the fungus rapid ohia death (ROD).

Kauai County Extension Agent Roshan Manandhar, with the UH College of Tropical Agriculture and Human Resources, says he’s been getting reports of the rust on the island since December.

It was reports from Wailua Homesteads resident Pamela Welch that finally led Manandhar to obtain samples.

Java plums, guava trees and some of the other plants impacted by the rust are considered invasive species on Kauai, so the response to finding the tree disease is different that it would be if native species were impacted.

“The samples were in good condition and had a lot of dead white urediniospores,” UH scientists wrote in the Wednesday email. “Found one unopened pustule which was the only one, with yellow spores. The rust was confirmed in this sample. A few teliospores were also observed.”

Welch said Wednesday that her concern is the rust is spreading.

“I live in the Homesteads and the trees are everywhere,” Welch said. “So far, the ones that are on my property are pretty much dead, just like the ones on the reservoir road.”

It starts with yellowing leaves. Then the plants slowly start to die. Welch says she’s seeing trees turning yellow all over the Homesteads.

“I’m not sure what’s going on, but the ones on reservoir road and in my yard aren’t recovering,” she said.

Scientists with CHTAR say the rust might be related to months of unseasonably wet weather. They also say the same genotype has been on Kauai for years.

Welch says she’s concerned the disease will spread to other plants on the island, and even if it just impacts java plum, that the landscape could be changed by the rust.

Manandhar says he’s keeping an eye on the situation.

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Jessica Else, environment reporter, can be reached at 245-0452 or jelse@thegardenisland.com.
Source: The Garden Island