UPLB testing chemical, biological agents against onion fungal disease

RESEARCHERS at the University of the Philippines Los Baños (UPLB) are developing sustainable chemical and biological control methods to curb onion anthracnose-twister disease, a major threat to the crop in Nueva Ecija.

Known as kulot by farmers, the fungal disease causes leaf spotting, twisting, and neck elongation, and can cut onion yields by as much as 80%, resulting in significant losses for onion cultivators.

Nueva Ecija, the top onion-producing province, accounted for 148,097 metric tons (MT) out of Philippine output of 264,323 MT in 2024, according to the Philippine Statistics Authority.

The research project, being carried out by the UPLB National Crop Protection Center, is evaluating biological control agents such as Trichoderma, as an environmentally sustainable alternative to chemical fungicides.

Trichoderma is a soil fungus known for acting as a biocontrol agent against plant pathogens.

The study, supported by the Philippine Council for Agriculture, Aquatic and Natural Resources Research and Development (PCAARRD), aims to determine how these agents suppress disease-causing fungi and whether they can help strengthen onion plants’ resistance to future infections.

Field assessments revealed that most growers cultivating red onion varieties rely heavily on chemical fungicides to manage the disease, while only a few have adopted Trichoderma as a biological control agent.

The researchers also collected fungal isolates, particularly Colletotrichum and Fusarium species, that are being tested against a range of fungicides to identify the most effective chemical treatments and to assess potential resistance among aggressive strains.

PCAARRD said the researchers also identified several possible alternative host plants, including barnyard grass, spreading dayflower, and sedges. Cross-infection studies will be conducted to determine whether these plants contribute to the spread of the disease. — Vonn Andrei E. Villamiel