Today is :

Technology

What could be the other ways to control the prevalence of diseases and insect pests that infests our crops aside from treating them with pesticides?  Are there any?  And if yes, is it efficient?

During the 1970's, Dr. Arcadio Quimio and Dr. Tricita Quimio of the Department of Plant Pathology at the University of the Philippines Los Baños (UPLB) developed a technology to control the two major diseases of mango:  anthracnose (Colletotrichum gloeosporioides) and stem-end rot (Lasiodiplodia theobromae).  The technology, known as the hot water treatment (HWT) involves the immersion of green mature mango fruits in a water bath for ten minutes at a temperature range of 52-55°C.  Through the said method, the development of the diseases in the infected fruits will be arrested because of the unfavorable environment for the pathogens brought about by the water's high temperature.  Studies have shown that the thermal death point of the disease-causing organisms for mango is at 51°C.

Through several laboratory tests, HWT was found to be effective in controlling the mango anthracnose and stem-end rot. Hence, the method was introduced to mango traders and was used in a commercial scale.  Halves of large drums served as the hot water tanks with wood fire and kerosene as the source of heat.  Later on, HWT was preferred over the used of fungicides in controlling the development of the mentioned diseases of mango considering that it was cheaper and safer.

The hot water tank
The first hot water tank was designed for the purpose of disease control through the HWT.  To fully maximize the potential of HWT in controlling the disease of mango, scientists at the Postharvest Horticulture Training and Research Center (PHTRC) in UPLB fabricated a hot water tank that can accommodate a larger number of fruits relative to the drums.  With an electronic heater as the source of heat, the hot water tank was designed to accommodate a batch of eighty kilograms of mangoes for disease treatment.

The prototype hot water tank is made up of galvanized sheets and coated with commercial paint to retard corrosion of the material.  However, the painting of the hot water tank is discouraged since chemicals that paint contains may diffuse to the fruits, hence may lead to its rejection in the international market.  Instead, in the commercial scale, the use of stainless steel for the construction of a hot water tank is recommended in replacement of the galvanized sheets.

Improved version
When the HWT treatment was used in a commercial scale, batches of eighty kilograms of mangoes are being accommodated by the hot water tank one after the other.  To take maximum utility of time and resources, another hot water tank was fabricated by the same group of scientists in PHTRC, this time larger and fueled by LPG tanks to function.

The improved version of the hot water tank was designed to accommodate double of its original capacity. A batch of 160 kilograms of mangoes can be accommodated by the improved hot water tank per treatment.  The electric heater as a source of heat was also replaced by LPG tanks and burners to minimize the high consumption of energy brought about by the electric heater.

Inside the tank are circulating pumps that keeps the hot water circulating and well distributed throughout the treatments for the fruits to be evenly treated.  A digital thermostat also accompanies the hot water tank to regulate the temperature of the water and maintain it to a desired point.  The hot water tank is also accessorized with wheels to aide the mobility of the machine.

Extended function
China is among the countries where the Philippine 'Carabao' mango is being exported.  Known for its strict quarantine measures, China's government ensures that the oriental fruit fly, a serious quarantine pest of mango for many importing countries, will not enter their premises.  To do so, China required the process of extended hot water treatment to be employed to the mango fruits that will be imported in their country.

The extended hot water treatment (EHWT) differs from HWT in several ways:  the former is used to disinfest eggs or larvae of the oriental fruit fly in the pulp of the fruit while the latter is used to control diseases.  Contrary to the HWT, in EHWT, mango fruits are immersed in hot water with temperature ranging from 48-49°C until the pulp temperature reaches 46°C and will he held for fifteen minutes.  Evidently, the procedure of EHWT requires a longer time than HWT to ensure that heat will go through the pulp of the fruit to kill the eggs and larvae of the oriental fruit fly.

In this regard, PHTRC, in collaboration with UPLB's College of Engineering and Agro-Industrial Technology (CEAT), is currently working to fabricate a hot water tank which can accommodate a batch of 500 fruits for the EHWT.  Since EHWT requires a longer time for its procedure, the need to fabricate a larger hot water tank was deemed necessary to save time and resources.

Commercialization aspect
According to Dr. Kevin Yaptengco, professor from CEAT-UPLB and research associate at the PHTRC, several steps were already taken with regards to the commercialization of the hot water tank.  Various trials and demonstrations of HWT and EHWT were performed in places where mangoes are widely produced.  In this way, mango traders and producers become acquainted of the two treatment methods.  Blue prints of the hot water tank are also provided to parties who are interested to have their own hot water tank.

Dr. Yaptengco also mentioned that there are mango traders and exporters who already make use of HWT and EHWT.  Large mango traders from Cagayan de Oro utilize HWT for disease control for the mangoes they export in Japan and Hong Kong.

With the combined efforts of PHTRC and CEAT-UPLB, the fabrication of the new hot water tank that can accommodate 500 kilograms of fruits is being looked forward, not only to showcase the hot water tank but the HWT and EHWT as well.

----------
For more information, please contact
Dr. Kevin Yaptengco, university research associate, Postharvest Horticulture Training and Research Center, University of the Philippines Los Baños, College Laguna with telephone number (049) 536-2444.