The Bhutanese Leading the way.
Pemaling Gewog in Samtse is facing a significant challenge as fruit drop rates has increased dramatically, impacting the livelihood of local farmers.
Agriculture extension officer, Dechen Lham, who has dedicated 10 years to working in the region before a transfer to Haa and subsequent return, reports that fruit drop has become a severe issue, affecting 30 to 40 percent of orange production. Upon her return in August, she received numerous calls from farmers concerned about the sudden increase in fruit drops.
She attributes the problem to the Chinese fruit fly, and notes that while training has been provided on handling fruit drops, many farmers have yet to adopt recommended practices.
She said, “One of the best methods is to pick up the fruit drop and then throw it in a pit that is 2 metres deep. Few of them have adopted it, and most have not, and when that happens, flies from other orchards spread.”
The situation is exacerbated in larger orchards, where more trees lead to higher fruit drop rates.
She pointed out that citrus fruit drop is a global issue, often resulting from poor management and the spread of flies as their population increases. Economic constraints have prevented the widespread use of chemicals, but this year, chemicals have been ordered through the National Plant Protection Centre (NPPF) to help those who rely on oranges as a cash crop.
“We have the chemical insecticide cypermethrin; I have given it to 25 households that have requested that it be spread throughout the tree. It’s the time of year when the moth or citrus fruit flies come around to lay their eggs, and right now the orange trees are producing marbel-sized fruits. The fly is eliminated by the insecticide. They should place an order a year in advance; thus, we want to order this for additional homes in the upcoming year,” she said.
Despite the challenges, Lham observes no significant environmental factors contributing to the increase in fruit drop, although villagers mention rising temperatures as a potential factor. She reiterates that hand-picking dropped fruits and burying them is an effective, economically sound method, but its success depends on community-wide participation.
“If one orchard practices handpicking methods, there are other orchards next to it that are left uncatered too, which becomes the breeding grounds for fruit flies, which then spreads,” she points out.
Dechen Lham said that farmers with significant income from oranges tend to take better care of their orchards, while those with alternative income sources may neglect the orange trees, contributing to the spread of fruit flies. Natural causes like wind and overburdened branches also contribute to some degree of fruit drop, along with the presence of shield bugs, though these factors are less significant.
However, the most critical period for fruit drop, due to citrus fruit flies, is in October and November, coinciding with the harvest season. She warns that if proper precautions are not taken, the persistent issue could severely impact farmers’s incomes, potentially leading to economic hardship and hopelessness. Efforts are underway with the gewog administration to address this issue, with a three-year plan to improve management practices and reduce fruit drop.
Lham is also in consultation with NPPF experts to use cypermethrin insecticide cautiously due to economic and environmental concerns. A more promising solution involves protein-based baits, which are economically sound and environmentally friendly, boasting a success rate of 70 to 80 percent. This method has been included in their plan, with budget allocations and proposals submitted to the Green Climate Fund.
Additionally, protein bait spray it is a cheap and simple IPM technique, but it works only when applied meticulously. The basic principle is that flies search for protein food, which they need to build their eggs. For selective control, we mix protein with an insecticide so that when the fly feeds, it will be poisoned and killed. For best result it should be done for 2 to 3 years with the destruction of fruit drops.
Dema Lham mentions the process of citrus fruit drop From June onwards, signs of oviposition by fruit flies can be seen, progressing to visible damage in the form of brownish spots and maggot infestations. The heavy fruit drop in October and November is particularly damaging, with dropped fruit often containing maggots or showing feeding signs.
To combat this issue, a proposal has been submitted to the Ministry of Agriculture and Livestock to provide selected households with protein bait and necessary equipment, transitioning to a cash-and-carry system for broader support. Alternative crops like areca nuts, ginger, and cardamom are being planted, though they do not match the income from oranges.
The agriculture extension officer advises the citrus-growing community to diligently pick up and dispose of dropped fruits to prevent pupae formation. With coordinated efforts and improved practices, there is hope for reducing fruit drop and restoring the prosperity of Pemaling Gewog’s citrus farmers.
