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Growing Durian and Pummelo Organically

By goGreen | February 29, 2012
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Seeing customers draw his durian close to their nose to check if these are ripe, Greg Tan was afraid that they might get cancer from the residues of synthetic pesticides he applied two days before harvest.

Feeling guilty, Greg then realized that selling shouldn’t be the sole objective of farmers like him for they have a social responsibility to provide consumers safe and healthful food.

Unfortunately, many farmers nowadays are unknowingly risking the health of consumers and their farm workers because they apply synthetic pesticides and insecticides. In durian and pummelo production, for instance, many farmers and agriculture graduates believe that it’s impossible, or difficult, to grow durian and pummelo organically.

Greg was one of them. In 1995 when he put up his 18-hectare durian and pummelo farm in Biao, Calinan, Davao City, he was using synthetic fertilizers 14-14-14, 16-20-20, 46-0-0, and 00-60 at recommended rate and time, and synthetic pesticides like cypermethrins, carbamates, organophosphates, and pyrethroids to control pests.

He was also using synthetic fungicides such as fosetyl-al, metalaxyl, Copper oxychloride, Cupric hydroxide, and thiophanate methyl to control diseases and spraying either glyphosate or paraquat twice a month to control weeds.

Greg’s strategy initially paid off. His durian trees grew fast and started to produce fruits three years after planting. In the fourth until the seventh year, his trees were bearing large quantities of fruits, more than what the trees could support.

He started having problems when many of his durian trees were infested with phytophthora and other diseases, especially during fruiting time. Application of fosetyl-al and metalaxyl at an increased rate and frequency, however, did not help. Worse, rhizoctonia and fruit borer infestation became serious, and bleeding stems and trunks of trees infested with phytophthora were also attacked by stem beetles, making it more difficult to control using synthetic insecticides.

The quality of his fruits deteriorated for these were damaged by diseases even at mature stage. As a remedy, Greg followed the advice of other durian farmers which was to apply fungicide two to three days before harvest to control the disease.

This, however, resulted in increased production cost until Greg himself was no longer making money from his farm. His farm -workers also became sickly possibly, because of the chemicals. And on top of his problems was the guilt he was feeling whenever he saw customers smelling his pesticide treated durian.



Greg was on the verge of giving up when his friend advised him to try organic farming to lessen his production cost and overcome his problems on pests. This pushed him to educate himself on organic fruit farming by researching and attending seminars.

It was in 2003 when he decided to apply his knowledge on organic fruit production even if his colleagues were telling him that it’s impossible to grow durian and pummelo organically.

One of the first things he did was to construct facilities necessary for the production of organic fertilizers and pesticides in his farm: He built a dim-lighted room measuring , 5 x 6 meters out of coconut lumber, ‘ bamboo and nipa for the production and storage of organic fertilizers and pesticides such as indigenous microbial organisms (IMO), fermented fish amino acid (FFAA), calcium plant nutrients (CPN), fermented fruit juice (FFJ), and lactic acid bacterial serum (LABS).

A part of the room was utilized for the production of organic pesticides such as oriental herbal nutrient (OHN) which was made of either garlic or ginger mixed with gin and other organic pesticide concoctions.

He also made beds for vermiculture and started raising 60 mature and improved goats-fed on a cut and carry basis-because he would process their manure and urine into pesticides, include in his compost, and feed to his vermi worms.

To have abundant supply of grass for the goats, he allowed native grass to thrive between trees and planted Florida and Guatemala Napier grasses. He also planted leguminous shrubs like indigofera, Rensonii, and Flemengia as additional feed and to enrich the nitrogen content of the soil.

Aside from shrubs and grasses, he also planted Panyawan, Derris, African neem trees, Acapulco, Madre de cacao, siling labuyo, and ginger as additional raw materials for the production of biofertilizers and pesticides.


One of the techniques on organic fruit farming that Greg has learned is to replace disease-prone durian varieties with the disease-resistant ones.

Among the varieties that are susceptible to phytophthora and stem beetle is Arancillo, a sweet and highly acceptable cultivar in the local market. Obosa Monthong which produces goodeating-quality fruits, is also highly susceptible to phytophthora even days before harvest.

Likewise, Greg cut down his Arancillo and Obosa Monthong trees and replaced them with Puyat, Marix 2, and Puang Manee which are resistant to phytophthora and have superior eating quality.

Another strategy to keep the trees healthy is to reduce the number of fruits; this is one way to prevent the trees from bearing fruits beyond their capacity which leads to stress.

Greg said that when trees are stressed, they become sickly and eventually die due to fruiting stress before the fruits mature. From 120 to 300 fruits, reduce it to 60 to 80 through systemic flower and fruit thinning, leaving only the properly shaped and superior fruits.

Greg believes that the success of organic farming anchors on keeping the soil healthy. So aside from having an excellent drainage system, timely irrigation, and pruning, farmers should also keep the soil conducive for the growth of beneficial microorganisms, which help dislodge phytophthora, by providing substantial amount of organic fertilizer.

Greg, for instance, produces organic fertilizer through composting-this is made of chicken dung, dried grasses, and kitchen wastes and vermiculture. He applies organic fertilizer at the rate of one-half to one sack per tree every six months and regularly sprays vermi tea, beneficial indigenous microorganisms (BIM), and biopesticides.


Aside from basal organic fertilizer, Greg applies foliar fertilizer such as IMO and FFAA.

To produce IMO, he fills half of a 15feet long clean bamboo tube set in horizontal position with cooked organic rice and covers it with Manila paper. Then he places the bamboo in a shady area of the farm and partially covers it with decaying coconut husk which gives the bamboo a sort of “dark room condition.”

The rice becomes moldy within three to four days and when it’s moldy, he mixes it with 2 to 3 kg of organically produced muscovado sugar and stores it in a 12-liter clay jar. Since IMOs are sensitive to ultra-violent rays of the sun, he wraps the jar with Manila paper before placing it in his cool and dim-lighted room. The sugar substrate in liquid form becomes moldy, an indication that IMOs exist.

Production of FFAA, on one hand, is similar with the production of IMO. Greg mixes fresh fish and muscovado sugar at 1:1 proportion and stores the mixture in a jar covered with Manila paper for seven to 10 days. He then extracts the juice of the rotting fish, or FFAA, and includes the extracted fish in his compost.

Greg applies IMO and FFAA as foliar fertilizer every two weeks. To prepare the fertilizer, he mixes 2 liters of FFAA and 2 liters of IMO with 200 liters of water in a drum and sprays the mixture to the plant foliage and around the plant base during the flushing stage of trees. But when the leaves of the durian trees mature, the concentration of IMO and FFAA should be reduced to 1 liter each per drum of water.

He also said that occasionally, IMO and FFAA are applied with foliar spray of broadleaves extract (juice of broadleaves soaked for three days in a drum of water) which supplies plants some micronutrients. The only synthetic fertilizer Greg uses, however, is potash which he applies in the form of sulfate of potash (SOP) at 60 days before harvest to enhance the quality of fruits.

To prepare organic insecticide, Greg mixes the leaves; flowers, and fruits of African Neem tree with the leaves of derris, pounded vines of Panayawan, ginger, pepper or siling labuyo, and Acapulco.

He soaks the mixture in a drum of water for three to four days. After soaking, he squeezes the mixture, mixes its extract with water, and then sprays it to plants every two weeks. This organic insecticide is also usually mixed with IMO and FFAA to reduce the cost of spraying.

Before, Greg was using the leaves of Indian neem tree until he found out that the flower, fruits, and leaves of African neem tree were more effective. In fact, fruit growers call this tree “malathion tree” because its extract smells like synthetic malathion.

Keeping the trees healthy lessens their susceptibility to diseases. But when the trunk is severely damaged by phytophthora, paste of alliete solution can be applied on infected parts. Panyawan extract or OHN preparation can be added to the paste when the tree is also infested with beetles.

Other diseases like rhizoctonia are insignificant in organic farming. Maybe this is because the disease-causing organisms are overcome by the beneficial organisms.

One of the practices that Greg has developed is the organic control of rind borer in pummelo. This is the most serious pest of pummelo and to which 70 percent of the synthetic insecticides in the market is developed for.

The pests start to attack at the onset of flowering because the aroma of pummelo flowers-Vietnamese use this to make perfume-attracts the adult moths which suck the nectars of the flowers and lay eggs. When the eggs hatch in a few days the larval borers will also attack the flowers and the developing fruits.

To control rind borer, he sprays goat manure and urine extract to the pummelo plants at one to two weeks interval at the onset of flowering. To prepare the extract, he soaks overnight 40 kg of fresh goat manure and 1 gallon of goat urine in a drum.

He then adds sili, ginger, and Panyawan extract or OHN to the goat manure and urine extract and then sprays the mixture to the pummelo plants. Apparently, the odor of the manure and urine drives away the moths of rind borer, and the OHN, Panyawan, ginger, and sili extracts kill the moth and the larvae. In this practice, the damage of rind borer is less than 5 percent.

Greg also applies this practice to control fruit flies, but when the fruits reach 60 days, he instead uses methyl eugenol bait in a trap.

In the conventional method of controlling rind borer, however, synthetic insecticides are sprayed from the flowering stage to 60 days at seven to 14 days interval.


To maintain the grasses at the height of 1 to 1.5 ft, Greg divided his farm into five blocks. Every week, he cuts the weeds in a block and feeds these to his goats which are now more than 100 head.

In the rainy season, however, his goats cannot consume all the weeds in a block and the leguminous pasture shrubs because they are growing faster and their volume increase. To control them, he includes the unconsummed grasses in his compost and feeds the unconsummed pasture shrubs to his vermiworms.


Greg made the right decision of shifting into organic fruit production because the quality of his fruits improved. The flesh of his durian fruits became soft and sweeter, and there are fewer incidences of maladies such as wet core and uneven ripening.

He was also able to produce more fruits even during the off-season and thus, he had more income for he could sell his produce at a higher price during off-season. Moreover, he was also making money from his goats whose manure and urine can be processed into organic pesticide.

The cost of production, of course, was significantly reduced because he no longer buys synthetic fertilizers, pesticides, and insecticides.

And most of all, Greg does not anymore feel guilty because his farm practices is healthy for the consumers and for the environment.


SOURCE: Agri Business Week


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