Natural agents can control onion diseases


Microbial control agents (MCAs) have the potential to fight diseases that usually infect newly-harvested onions, and could help farmers store harvests longer and earn higher prices, according to ongoing research by Postharvest Development and Mechanization (PhilMech), an attached agency of the Department of Agriculture.

PhilMech Executive Director Dr. Dionisio Alvindia (Scientist III) said initial tests at a laboratory scale were conducted to test the effect of Bacillus spp. strain DGA14 and Trichoderma spp. strain DGA02, which are two species of epiphytes, against pathogens affecting newly-harvested onions.

DGA02 and DGA14 are being tested on pathogens taken from infected bulbs like Aspergillus niger, Erwina carotovora, Fusarium sp and Sclerotium roifsii.

So far, tests conducted at a laboratory scale showed DGA02 and DGA14 could suppress the pathogens with a formulation of 12.5 percent diluted to one liter of water.

It present, there are no options to contain post-harvest diseases of onion, and that is the reason why farmers immediately sell their harvests at low prices, Dr. Alvindia said.

If farmers are able to contain the post-harvest disease affecting onions with MCAs, they can store their harvests longer and ask for better prices from traders and buyers, he added.

The effectivity of using MCAs to fight diseases in crops was already proven by PhilMech against the banana crown rot.

Field trials conducted by the agency on a commercial export scale showed DGA14 and DGA02 were both effective MCAs in combating the crown rot disease. The field trials were led by Dr. Alvindia when he was the principal researcher of the Biological Control Agents Project of PhilMech. His colleague Elijah Davalos participated in the field tests. Trials showed the rejection rate for bananas bound for the export market could be brought down to as low as 1.5 percent using MCA-formulated dip treatment. The usual rejection rate was from 7 percent to 20 percent.

The Food Protection Division of PhilMech also had notable studies on botanicals as protective spray against storage pests like grain weevils and borers. Among them were ikmo leaves, jathropa, neem and atis seeds.


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