Written by Ella Lois T Bestil
Fight fungus with its kind.
A recent study found that a certain fungal isolate can reduce sheath blight damage on rice. The fungus, Aspergillus sp. of an unknown species, was found to retard the growth of Rhizoctonia solani (R. solani), a pathogen or microorganism that causes sheath blight. Sheath blight is considered one of the major rice diseases causing up to 50% yield loss.
In the study, Fungi from organically fertilized soil and their biological potential against Rhizoctonia solani, causal organism of sheath blight in rice, researchers Leilani Sumabat of Philippine Rice Research Institute (PhilRice) and Teresita Dalisay found 13 promising out of 110 fungal isolates to control the sheath blight-causing fungus.
“Among the tested isolates, Aspergillus sp. was found to be the most consistent in controlling the pathogen in small plots,” Sumabat said.
Aspergillus sp. leeches on R. solani, a mechanism called mycoparasitism. The fungal isolate coils on the hyphal strand, the pathogen’s mode of growth, then disintegrates the strand, preventing growth.
Sumabat said sheath blight manifests first in leaf sheaths through oval gray spots with black brown margins that later enlarge. Preventive and control measures include sanitation, reduced seeding rate, and efficient use of nitrogen fertilizer. PhilRice also promotes the use of biological control or biocon as an alternative on managing diseases.
Sumabat said fungus as biocon agents are available in organically fertilized-soil. Organic matter from compost and micro-nutrients enable soil-borne microorganisms to reproduce.
“It is assumed that organic cultivation of the soil will increase the abundance of microorganisms that can help prevent the occurrence of sheath blight in rice,” Sumabat said.
However, formulation and system of applying the biocon to the plant is still yet to be explored. Sumabat said the study provided a good lead in identifying a promising fungal isolate that can potentially be used and commercialized as biocon.
The study was conducted at the University of the Philippines Los Banos. It is a recipient of the T.H. Quimio best thesis award by the Mycological Society of the Philippines and the Gamma Sigma Delta honor society of the Philippines-Los Baños chapter.