A senior agriculture official announced that three kinds of insects have affected over 50,000 hectares of rice in five border provinces along the Vietnam-Cambodia border, in a video released by the Ministry of Agriculture, Forestry and Fisheries on July 14.

The official said, however, the situation is under control and farmers are advised not to sow excessive amounts of rice seed or use too much nitrogen-based fertiliser.

Insects such as rice whiteflies (Aleurocybotus indicus), fall armyworms (Spodoptera frugiperda) and rice leaf folders (Cnaphalocrocis medinalis) are present in Takeo, Prey Veng, Svay Rieng, Kandal and Tbong Khmum provinces.

According to Ngin Chhay, director-general of the general agriculture department, said the damage is still minimal and mostly affecting Prey Veng, with the least impact in Kandal province.

“Whiteflies broke out over three weeks … but the damage is still small. The most significant impact is in Prey Veng,” he said.

Rice is grown on about 240,000 hectares in the province, with over 40,000 hectares affected. The overall damage is minimal, accounting for about four per cent of the total rice cultivation area, he added.

“The damage is estimated at about 10,000 hectares. Not all rice is affected; some rice paddies are completely destroyed, some are about 50 per cent damaged and some are about 70 per cent damaged. The outbreak of whiteflies so far is not serious, and the situation is manageable,” Chhay claimed.

The flies destroy rice at various stages of growth. If they attack the rice during the early stages of growth or when the rice begins to bloom and form pods, it can cause significant harm. At this stage, flies destroy the Tong Chhey leaf, the top leaf below the pod, which then dries and breaks, greatly reducing yields, he explained.

He added that if they attack during the tillering stage, damage may not occur because the rice can regenerate after timely intervention by farmers by spraying pesticides to kill the pests.

“Rice fields that have been severely damaged are due to mixed infestations. When whiteflies start to destroy the rice, rice leaf folders often follow, causing severe damage of up to 100 per cent in some fields, while others are up to 50 per cent damaged,” he said.

However, Chhay noted the damaged paddy fields are being gradually plowed and replanted, as there is still ample time until August, during which the rain will continue to fall.

He also noted the destruction caused by the insects primarily affects non-seasonal rice. Seasonal varieties have not been harmed, despite the presence of the pests. Additionally, paddy fields that are overplanted or use too much nitrogen-based fertiliser are the worst affected by the outbreak.

“Fertiliser use should be based on the condition of the soil and the stage of growth of the crop. Farmers should avoid using too much [nitrogen] as it makes the rice grow very green and tender, attracting flies, leaf-folder worms and brown plant hoppers,” Chhay suggested.  

He also called for farmers not to use excessive amounts of seeds in cultivation. On average, if they are well cleaned, only 150kg per hectare should be used. If they are not clean enough, a maximum of 200kg per hectare should be used.

In addition, he said farmers need to regularly inspect their fields for insects to take timely and effective action in collaboration with relevant officials.

More than a month ago, an outbreak of fall armyworms affected more than 20,000 hectares of rice in 18 provinces. The agriculture ministry took strong action by sending an effective and immediate intervention team. So far, no serious armyworm infestations have been reported, with only a small number present in some areas.

Sim Hen, a farmer in Prey Veng’s Preah Sdach district, said that about seven hectares of her rice had been affected by whiteflies. She said most of it could not bloom and was damaged despite her husband's efforts to spray pesticide and fertiliser.

“We will not replant rice in the damaged paddy fields because we are worried that it will be destroyed by flooding,” she added.