Lisa Schattenburg-Raymond of the Maui Nui Botanical Gardens examines one of the garden's native Hawaiian bananas, the popo'ulu. Historically, this is one the few varieties that women were allowed to eat. Timothy Hurley • The Honolulu Advertiser

The Marquesans brought several varieties of bananas with them when they originally populated Hawai'i. Through the centuries, the prolific farmers in Hawai'i tended to the bananas, not only for life-giving sustenance and other uses but as a kind of hobby, developing at least 50 or so known varieties.

Today, these "Polynesian heirloom" bananas, as some call them, are rapidly disappearing, and experts warn the virus could strike a crippling or even fatal blow.

That would be a shame, says Angela Kay Kepler, a Maui biological consultant who is writing a book about Hawai'i's native bananas with her husband, Frank Rust, and University of Hawai'i horticulture professor Chian Leng Chia.

"They are the equivalent of Hawai'i's precious feather capes. They are part of the culture just like many of the other things you see in the museums," Kepler said.

State agriculture officials have been battling banana bunchy top virus for 15 years, warning of the serious consequences for banana growers across the state. The virus has caused the demise of some farms and forced many others to replace their existing banana variety with less-susceptible ones.

The virus was first observed here in 1989 and is widely established on O'ahu. It has since spread across the island chain — discovered on the Big Island in 1995 and on Kaua'i in 1997. It was found for the first time on Maui at the beginning of last year.

Infected plants typically suffer severely stunted growth in the plant crown, resulting in a bunchy appearance. Younger leaves are stunted with yellowish edges. Infected plants produce small, deformed fruit and, in advanced stages of the disease, there's no fruit at all.

The bad guy is the banana aphid, the disease's sole vector. Although the aphids can be spread by winds, authorities say people do more to aid and abet the disease's proliferation by inadvertently moving infected plants from one area to another. The virus is very difficult to detect in its first year and, because of that, it's capable of spreading quickly.

Eradication is extraordinarily difficult, authorities say, and the likelihood of finding a cure is slim. Destroying the infected plants is the only known way to battle the disease.

Meanwhile, the number of native Hawaiian varieties continues to dwindle, in part because of the bunchy top virus. Collections in Waimänalo and on Kaua'i have been destroyed in efforts to eradicate the disease. From the 50 or so original varieties, only 27 are known to exist.

"We're hoping there are still a few varieties in the mountains of O'ahu and Kaua'i," Kepler said.

Kepler and Rust began writing a book on tropical fruits and nuts in Hawai'i a couple of years ago and then decided to focus on the native bananas after professor Chia suggested the topic had become urgent in light of the burgeoning disease. The more the couple began to research the bananas, the more fascinated they became.

In ancient Hawai'i, bananas were taboo to women except certain varieties. According to Mary Kawena Pukui and Samuel H. Elbert, bananas were not mentioned in songs because of some negative connotations, including the fact that it was considered bad luck to dream of bananas, to meet a man carrying bananas or to take them in fishing canoes.

Schattenburg-Raymond said the Hawaiians were fascinated with the banana mutants and worked arduously to reproduce the oddities in greater numbers. Among them is the only variegated, or striped, banana cultivar known to grow anywhere. Examples are found in the Maui Nui Botanical Gardens in Kahului.

With 19 known native varieties still alive on Maui, the Valley Isle is the capital of native bananas, so to speak, and research for Kepler and Rust has sent them to such places as the remote jungle of Nähiku and the urban back yards of Kahului.

Discoveries include one variety, previously thought to be extinct, in the back yard of a home in Upper Kula, at the 3,400-foot level, as well as a group of 65 rare mai'a maoli kaualau in a West Maui valley. In addition, they found 70 plants of the huamoa variety on a Wailuku farm being grown for the Samoan niche market.

With only a small bunchy top virus infestation in Pukalani and Makawao, Maui is the least-impacted of the major islands. Kepler and Schattenburg-Raymond would like to keep it that way. They are urging the state to beef up its team of field inspectors — and its public-education efforts — to make sure the disease is contained.

"All of our bananas are threatened until they eradicate this," Schattenburg-Raymond said.