During the pandemic, Hawaii’s flower growers struggled to keep from permanently shutting down. A year later, Covid-19 cases have declined and restrictions have loosened. But flower growers face another threat.

Plant viruses are leading to a decline in red ginger production. Some flower growers have stopped growing it in the last five years because of the high mortality rate. 

This worries Shane Castillo, who specializes in red ginger and other tropical plants on Hawaii island. The owner of C&C Tropicals has been growing and selling red ginger for three years on more than 10 acres.

Hawaii island has the largest number of red ginger farms. In 2009, there were many backyard ginger growers, according to Castillo. After the pandemic, there are fewer than 20 growers – backyard and commercial – left on the island. Oahu was severely affected, too, with most of the spread occurring in several farms on the Windward Coast. 

Castillo is happy to be one of the few left to be able to offer red ginger. “During the pandemic, my feelings and passion have gone through the roof,” he said. “There’s a lot of people that passed away, and now we have people who bring flowers for the deceased and the living. It brings me joy to just see the smile on their faces, the happiness and texts that say ‘thank you.’ We hear from customers that this particular red is their grandmother’s favorite color, and they will send her off into the next world.”

The plant is significant to florists and flower growers because of its cultural importance. Red ginger is commonly used in cultural practices and funeral services. The plant, which originated in Malaysia, has been called the “poster child” of tropical flowers. Its lush, vibrant features add a tropical flare to gardens and other landscapes. 

A 2020 report found the root cause of the decline in red ginger is in several viruses and fungal pathogens. 

According to Russell Galanti, who co-authored the report, a combination of six viruses was detected in red ginger. Two new viruses have yet to be named. 

“It’s not just new to ginger, it’s new to science completely,” said Galanti, extension agent at the University of Hawaii’s Department of Tropical Plant and Soil Sciences. 

The four known viruses are Canna Yellow Mottle Virus, Banana Bract Mosaic Virus, Bean Common Mosaic Virus and Banana Streak Virus. The most common in red ginger is the Canna Yellow Mottle Virus.

The viruses are spread by pests such as mealybugs and aphids, which are found in warmer climates and feed off the plant’s sap.

The study began in 2019 after Kaneohe farmers noticed their red ginger crops were plummeting.

Galanti and a group of researchers found that most of the spread of the ginger virus was on Oahu and Hawaii island. 

For flower buyers, it can be difficult to tell if a plant is infected because some show hardly any signs. Galanti said the primary symptom is discolored leaves, including yellow stripes.

The study lists 17 other signs of infection, including stunted plants and deformed leaves. 

Some flower growers have stopped growing red ginger because of the low survival rates. There’s currently no cure, Galanti said. 

“Once a plant has a virus, it’s not like humans, they don’t have any antibiotics,” Galanti said. “We don’t have solutions for them. So when a plant is infected, you either live with the virus in the plant or you get virus-free plants.”

However, Galanti said that he and other researchers are seeking grants to research how to grow virus-free plants.