New onion disease discovered

A new disease attacking onion has been discovered in the Nueva Ecija town of Talavera.

It has been tentatively identified as Stemphylium-Purple Blotch Leaf Blight Complex, a fungal disease of plants caused by Stemphylium visicarium and Alternaria porri.

The pathogen (causative agent of the disease) is currently being isolated for characterization at the Philippine Rice Research Institute (PhilRice) in nearby Muñoz town.

The characterization is being done by the pathology group of the PhilRice Integrated Pest Management Collaborative Research Support Program (IPM CRSP) led by Dr. Ronaldo Alberto.

The IPM CRSP program, headed by PhilRice executive director Santiago R. Obien, will subsequently send the pathogen to the Commonwealth Mycological Institute in England for positive identification.

Alberto said the disease was first reported in Barangay Lomboy and neighboring barrios of Talavera by participants in a recent "Season-long Training on Onion IPM" and plant pathologists of the IPM CRSP Program.

The training was sponsored the DA-National Agriculture and Fishery Council.

It was the first report of the disease in Nueva Ecija, appearing right after two consecutive weeks of rain last February. Farmers in the area said it was the first time that such a disease attacked their onion crop.

The disease has progressed in an epidemic scale in just a few days. Some 80 hectares planted to onion have been affected. And the area continues to widen as the pathogen is air-borne and can be easily carried by wind.

Infected areas stand to lose 40-50 percent of the crop, especially if the crop was infected at bulb formation stage.

Alberto said the disease has been observed to be in association with the purple blotch disease (locally known as "palak").

Symptoms at early stage are small light brown spots on the leaves (similar to purple blotch) that soon develop into elongated, spindle-shaped spots that often reach the leaf tips.