Spoiled grapefruits at Phan Thi Phuong's garden in Ben Tre Province. Photo courtesy of Tuoi Tre
Southeast Asia's indomitable citrus fruit borer has been destroying millions of dollars in Vietnamese crops and local scientists have no way to stop the worm eating up all the Mekong Delta's sweet-tasting plants.
Farmers in grapefruit provinces of Ben Tre and Tien Giang said they have had to cancel many export orders as the worm, known scientifically as Citripestis sagittiferella, has destroyed thousands of hectares of grapefruits and oranges across the delta, Tuoi Tre reported Monday.
The worm, found in Indonesia, Malaysia, Singapore and Thailand, first appeared in local orchards around two years ago, farmers said, adding that recent months have seen many outbreaks of the pests.
Many gardens promised a profitable season but all fruits dropped before harvest time as they were eaten from the inside by the worms, they said.
Continuous losses have caused many farmers to give up cultivation altogether.
Phan Thi Phuong from Ben Tre Province owns a garden of 150 six-year-old grapefruit trees, but she has left more than 50 to die.
"The worms have been attacking 80 percent of every crop, so I have no more interest in taking care of the garden any longer.
"I have been trying different methods, like spraying pesticides or putting up camphor (a strong-smelling antiseptic compound), but they did not work. I just made more losses," Phuong told Tuoi Tre.
The Southern Plant Protection Center warned that thick-skin oranges would be the next major victim as there are now fewer grapefruits in Vietnam.
It said the worm is occupying all Mekong Delta provinces and has attacked around 8,000 hectares of citrus fruit gardens, or more than 10 percent of their entire area in the delta, and those numbers are increasing.
Recent research by Can Tho University, the biggest institution of higher learning in the delta, said the worm, which comes from a species of snout moth, penetrates into the core of the fruits, eating them from within, only coming out when it's time to grow into a cocoon.
Thus, spraying pesticides do no harm to the worm, the research said, suggesting that farmers cover the fruits to protect them from the worm in the first place instead.
It said that such covering costs around VND2,000 per fruit while each grapefruit can be sold for up to VND100,000. Covering is recommended after the fruits are cleaned and sprayed in advance. Extra fertilization is also recommended.