More than 20,000 of over 210,000 hectares of rice in Prey Veng province have been affected by rice whiteflies (Aleurocybotus indicus) since the end of June.

Sam Sarun, deputy director of the Prey Veng provincial Department of Agriculture, Forestry and Fisheries, said the outbreak began on June 30. He noted that 23,000 out of 216,000 hectares of rice in 11 city-districts out of 13 have been affected so far.

“Some of the rice affected early by the flies … has already suffered some damage. More than 20,000 hectares of rice have been affected, with about 10 per cent potentially damaged, but we are waiting for the assessment," Sarun said.

He explained that the whitefly outbreak originated in Vietnam, where it caused significant damage. A single whitefly can lay up to 200 eggs, and if not promptly addressed, the rice will turn reddish about a week after the eggs are laid.

“If farmers see this and take immediate action, [the outbreak] will not seriously affect them. But some farmers did not visit their fields until the rice turned red,” he said.

“By the time it's in this condition, we can't help anymore. It's like a person with advanced cancer visiting a doctor; there's little the doctor can do. We can only prevent the damage when the flies have just landed on the rice,” he added.

He noted that local authorities and a national team worked with a private company to use drone spraying techniques free of charge on July 3. However, after this, if farmers need to spray large areas of land, the company charges between 40,000 and 50,000 riel [about $9.75-$12.20] per hectare. According to Sarun, this is about the same cost as employing a worker to spray.

Local authorities and a national team work with a private company to use drones to spray fields with pesticides free of charge on July 3. Agriculture ministry

He noted that spraying with drones is faster and does not affect people's health as much, whereas spraying with a pump is slow and can seriously affect the health of the sprayers.

“Using spray pumps could not intervene in time; using drones is better. The drones spray efficiently ... But if we spray one field without treating the adjacent ones, the flies will come back,” he said, adding that so far, spraying seems to be gradually taking effect.

Therefore, he believes the outbreak will be largely controllable.

Sim Hen, a 47-year-old farmer in Preah Sdach district, said that seven out of 10 hectares of her rice fields were being destroyed by flies despite her husband's efforts to spray them.

“My husband is spraying every day, but it does not seem to help. The rice could not bloom and could not breathe because [the whiteflies] stop it,” she said.

“The rice in some places bloomed a little. But almost everywhere in my field is damaged. It turns red and dies. I visited the rice, saw the situation and stopped visiting it,” she added.

Hen claims that she spends more than 3 million riel (about $730) per hectare to grow rice, which does not include the current cost of spraying.

Kong Kea, director of the rice department at the agriculture ministry’s general agriculture department, explained that some whiteflies are present in Cambodia, but previously, not in significant numbers. This year, he said the flies have proliferated and are very active, causing serious damage to crops due to the hot weather and prolonged dry season, which increases the life cycle of the pests.

He called for farmers to regularly visit their rice paddies for timely intervention in case of an attack.

The Prey Veng provincial administration held an emergency meeting with relevant authorities on July 4 to address the problem of damage caused by the whitefly outbreak.