SCIENCE CITY OF MUÑOZ (PIA) — The Philippine Rice Research Institute (PhilRice) advised rice farmers to avoid unnecessary insecticide spraying on rice leaves to better manage rice stem borer infestation.
PhilRice Crop Protection Division Chief and Science Research Specialist Genaro Rillon said leaf spraying is often ineffective because stem borer larvae feed and develop inside the rice stem.
Rillon explained that stem borer infestation may occur from the vegetative stage until flowering, causing deadheart in young plants and whitehead during the reproductive stage.
“Female stem borers lay eggs that hatch into larvae, which bore into the rice stem; when infestation occurs at the early growth stage, the central leaf dies, a condition known as deadheart, while infestation during the reproductive stage damages the panicle, resulting in empty grains or whitehead,” he said.
He noted that severe infestation can reduce rice yield by one to 20 percent or even higher, especially in fields with a high number of whiteheads.
Rillon stressed that monitoring stem borer egg masses on rice leaves is a more reliable basis for control decisions than visible damage such as deadheart or whitehead, which already indicates crop loss.
He added that many beneficial insects and parasitoids naturally attack stem borer eggs, significantly reducing pest populations in the field.
Rillon warned that unnecessary insecticide spraying may kill these natural enemies and disrupt the balance of the rice ecosystem, leading to pest resurgence.
“Second, farmers should observe natural enemies, particularly the many parasitoids that attack stem borer eggs, and avoid unnecessary insecticide spraying; after harvest, rice stubbles should be plowed under to remove food sources and habitats, helping reduce stem borer populations in the next cropping season,” he pointed out.
He further encouraged farmers to practice synchronous planting and proper field sanitation, including plowing under rice stubbles after harvest, to reduce stem borer population in the next cropping season.
PhilRice continues to provide guidance and promote proper pest management practices to help farmers protect rice yields and minimize production losses in Nueva Ecija. (CLJD/MCAL, PIA Region 3 – Nueva Ecija)
