HiYEAST controls postharvest diseases in crops

MANILA, Philippines - Significant losses in fruits and vegetables are primarily due to postharvest decays caused by harmful microorganisms or microbial pathogens.

A research project found that HiYEAST, a biocontrol agent, can effectively control postharvest diseases in mango, banana, calamansi, peanut, onion, garlic, and tomato.

The project was funded by the Philippine Council for Agriculture, Aquatic and Natural Resources Research and Development of the Department of Science and Technology (DOST-PCAARRD) and implemented by the National Institute of Molecular Biology and Biotechnology (BIOTECH) of the University of the Philippines Los Baños (UPLB) through the leadership of Severina Exconde.

Exconde’s research was driven by the need to develop new and safer methods of controlling postharvest diseases in lieu of synthetic fungicides that reportedly pose risks to human health and environment.

One such method is the biological control approach of using microbial antagonists such as yeasts, fungi, and bacteria. Applying yeasts, in particular, as biocontrol agents for postharvest diseases offers a promising alternative to chemical control.

Exconde screened 47 isolates, of which 27 showed antagonistic activity against fungal and bacterial pathogens. Antagonistic yeast isolates were developed into biocontrol agents or products using a carrier and binder. Tests on toxicity showed that the products are safe to humans.

Two of the yeast products were named as HiYEAST, particularly HiYEAST Dh (Debaryomyces hansenii) and HiYEAST Sc (Saccharomyces cerevisiae). These biocontrol agents are in powdered form and packed in polypropylene bags. Each pack contains 20 grams of the HiYEAST powder.

Laboratory and pot experiments showed that HiYEAST Dh was effective against crown rot and anthracnose. These are postharvest diseases in banana caused by the fungus Colletotrichum musae. It was also effective against Aspergillus flavus, a fungus which causes production of aflatoxin in garlic and nuts.

On the other hand, HiYEAST Sc was effective against anthracnose, a major postharvest disease of mango caused by Colletotrichum gloeosporioides. Hi-YEAST Sc was also effective against aflatoxin-causing disease in garlic and green mold disease in calamansi caused by the fungus Penicillium digitatum.

In terms of application, the product can be simply sprinkled on onions and garlic. For banana and calamansi, mix thoroughly one pack of HiYEAST in 20 liters of clean water and submerge the fruits into the mixture for 30-40 minutes. Dry them before storing. Make sure that the fruits are clean and without latex before applying HiYEAST.

Exconde said “integration with other existing postharvest treatment such as hot water treatment must be considered to bring about a more complete disease control or management. More packing house trials must be done and preharvest treatment of mango, banana, tomato, garlic, onion, and peanut must also be considered.”

Further studies will be undertaken to evaluate effects of the yeast application on the control of postharvest diseases in crops in production areas. Hence, the products are not yet commercially available.