The Philippine Rice Research Institute (PhilRice) has urged farmers to monitor their rice fields as threats of pest attacks increase during the rainy season.

According to Leonardo Marquez, PhilRice crop protection expert, unmanaged infestations can result in yield losses of 15 percent or more, as he pushed for early pest detection and management.

This after findings by the Pest Risk Identification and Management Project identified over the past five years in 53 provinces five major pests threatening the staple grain: brown spot, deadheart, leaf blast, sheath blight and whitehead.

“This analysis involved 19 monitored pests, with data indicating that pest incidents are more frequent and severe during the wet season,” Philrice’s report on Monday said.

Based on the Department of Agriculture-attached corporation’s survey, brown spot, which is a fungal disease affecting rice at all growth stages, was prevalent in Western Visayas last December, with incidents exceeding five percent in Antique, Aklan, Capiz, Iloilo and Negros Occidental.

The disease can cause stunting, yellowing, dry leaf, short panicles and empty grains. Rice growers were advised to use high-quality seeds, apply potassium-rich fertilizer and use fungicides.

Meanwhile, deadheart, which is linked to stem borer infestation, has high incidence rates in Iloilo.

It was reported that if a crop is affected by this disease during flowering, it can result in a 30-percent yield loss. Farmers were urged to monitor stem borer moths.

Burn affected rice

Leaf blasts, on the other hand, were reported to be more damaging during the rainy season. PhilRice said their impact can be mitigated through effective management, including avoiding excessive nitrate nitrogen, maintaining proper water depth, and burning affected rice straw to eliminate spores.

Sheath blight, which is a concern in Antique, Capiz, Iloilo and Negros Occidental, can reduce yields by up to 25 percent if left untreated.

The disease is reported to pose a significant threat, especially in irrigated fields with heavy rainfall and excessive nitrogen fertilization.

Lastly, due to stem borer attacks, whiteheads can disrupt the rice crop’s nutrient flow and lead to panicky death.

Farmers are advised to avoid using pesticides for 30 to 40 days after planting, promote beneficial insects, and monitor butterfly populations.

Last May, the state weather bureau Philippine Atmospheric Geophysical and astronomical services administration declared the official onset of the rainy season in the country. Thirteen to 18 tropical cyclones are expected to enter the Philippine area of responsibility this year.