Growing Durian Sans Chemicals
Thanks to Bio-fertilizer, Bio-fungicide, a Predator Wasp and Botanical Pesticides, an orchard owner can now produce organic durian. His trees don’t only give higher yields, they also produce fuller fruits with better rating quality.
If you ask the fruit experts, they will most likely tell you that it is impossible to produce durian without using chemical pesticides and commercial fertilizers. After all, durian is highly susceptible to phytophthora, the most serious disease of durian, as well as to other diseases and pests. Phytophthora affects all parts of the tree – the roots, the trunk, the branches and the leaves. It could be so devastating that growers often spray a lot of fungicide to prevent its occurrence or to control the same.
One durian grower in Davao City, however, is proving that he can produce durian without using chemical fertilizers and pesticides. He is Antonio “Ony” Partoza, lawyer-businessman, who has a 9.5-hectare durian plantation in Brgy. Biao Escuela, Davao City, and a 15-hectare durian and longkong orchard in Panabo, Davao del Norte.
He has 550 durian trees that were planted as early as 1987 in Brgy. Biao Escuela, and some 600 five-year-old durian trees in Panabo.
In Biao, 300 of the 550 trees are of the Arancillo variety while the rest are of the Monthong, Chanee, Kanyao and Puyat varieties. In Panabo, he has mostly the Arancillo variety. He has a special liking for Arancillo because it is very prolific and has superior eating quality. The taste is closest to that of the native durian which is preferred by durian connoisseurs. Although the fruit is small, it is fleshy. The small size of the fruit (1 to 1.5 kilos each) is considered an advantage, marketingwise. Being small, it is much easier to sell than the big varieties. For instance, at P80 per kilo in the retail market, the Arancillo is very affordable to consumers. In the case of other varieties such as Chanee which may weigh as much as 5 to 6 kilos each, one 5-kilo fruit would have a price tag of P400 which may not be affordable to many buyers.
The big problem with Arancillo, however, is that the tree is highly susceptible to phytophthora disease. All other varieties are also attacked by the disease but Arancillo is much more so, according to Partoza.
For the past many years, his plantation in Biao Escuela was under the care of an overseer who did not take good care of the trees. Ony was more busy with his business of distributing processed food products of a big Manila firm and the distribution of major Manila newspapers and magazines (including this magazine). As a result of neglect, many of his durian trees were badly affected by phytophthora. Many of them lost their fruiting branches. Big portions of their trunks bear scars due to the disease. There were yearly mortalities, too.
About two years ago, Ony decided to take active management of his two orchards. He resorted to the use of a bio-fertilizer instead of the traditional chemical fertilizers. Also, he is now using a bio-fungicide instead of the very expensive chemical fungicides, and to control insect pests, he is using a predator wasp and botanical pesticides.
As a result of his shift to a purely organic production system, Ony has been able to cut his production cost. More importantly, he has rehabilitated his diseased trees. They are more healthy now and are producing better quality fruits. He recalls that when he was not yet using organic inputs, about 80 percent of his durian fruits were misshapen. Some segments of the fruits were not fully filled due to incomplete pollination of the flowers. Probably, he says, there were not enough insect pollinators in the farm because of the insecticides and fungicides sprayed on the trees. Today, the situation has been reversed. About 80 percent of the fruits are now fully filled. He believes there are now more beneficial insect pollinators as a result of the non-use of chemical pesticides.
And what are his organic inputs? Let’s take them one by one.
Bio-fertilizer. This is a compost enriched with beneficial microorganisms. He himself makes the compost out of locally available materials such as shredded durian shell from his own farm, cacao pod shell from nearby farmers, carbonized rice hull, chicken dung and carbon sludge. What he calls carbon sludge is actually powdered coconut charcoal which is a waste product from a nearby activated carbon factory. This is black and it makes the compost very dark.
With the use of an activator, he can turn his shredded raw materials into compost in just two weeks. Other compost makers who don’t use any activator may take them several months to produce a ripe compost, according to Partoza.
Ony’s compost consists of about 30 percent carbonized rice hull, 30 percent durian or cacao pod shell, 30 percent chicken manure and 10 percent carbon sludge. The materials are thoroughly mixed in a motorized mixer that he has specially fabricated. The finished compost is uniformly fine-textured. Before applying the compost to his trees, it is enriched with an inoculum which he buys from Ecologic Ventures in Pasig City. This enrichment inoculant, he says, adds nitrogen-fixing bacteria to the compost and is also a phosphorus solubilizer. This means that it makes the phosphorus in the soil readily available for absorption by the roots.
One pack of the inoculant (a powder) which costs him P600 is enough to inoculate one ton of compost. Two kilos of the enriched compost is applied on one-year-old durian trees. For trees that are 10 years old or older, he applies 20 kilos per tree two times a year. This is applied under the tree’s canopy, buried two inches in the ground. After application, the same is watered to enhance proliferation of the beneficial microorganisms.
Bio-fungicide. Phytophthora is the most destructive disease of durian. But Ony does not worry anymore about this disease. He thinks he has tamed this disease with his bio-fungicide. The bio-fungicide is also applied through his compost. One pack of the bio-fungicide inoculant which is good for one ton costs P3,000. The inoculated compost is applied in the soil as well as in the affected trunks or branches. On the ground, the topsoil of 1.5 meters around the trunk is temporarily removed and 25 kilos of bio-fungicide inoculated compost is spread. Then the topsoil that was removed is placed back.
On branches and trunks, the affected spots are scraped and the bio-fungicide is plastered over them. The biofungicide could be put in place by wrapping the same with plastic similar to the procedure in marcotting.
Pests. Durian is susceptible to different insect pests, including species that pass through larval stage and others that don’t. For the control of insects that produce larvae, Ony uses a parasitic wasp which he sources from a retired entomologist of the Department of Agriculture based in Gen. Santos City. The wasps lay their eggs on the larvae of the insects which eventually kill them.
For other insects such as aphids and hoppers, he uses fermented extracts of tuba-tuba, tubli (derris) and panyawan (makabuhay among Tagalogs).
The roots of tubli are crushed and fermented in water for five days. The liquid is strained and used as insecticide spray.
Overall, Ony is very satisfied with his use of organic fertilizers and pesticides. And he is willing to share his experiences so that others can also benefit from his system. By the way, he is the president of the Mindanao Fruit Industry Development Council which is promoting the interests of the Mindanao fruit growers. He can be contacted at 0920-904-1940.
By Zac B. Sarian