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Preventing infestation sans chemicals


By Zac B. Saria

Eggplant is one of the favorite vegetables in the country. Unfortunately, it is also the favorite crop of insect pests so that oftentimes farmers have to resort to excessive spraying of deadly chemicals.

  • SUSCEPTIBLE TO FRUIT AND SHOOT BORER – Eggplant is a favorite vegetable among local consumers. Unfortunately, it is also a favorite of insect pests that bore holes into its fruits and stems. This is one reason why many farmers resort to excessive spraying with chemical pesticides. There are safer ways, however, of preventing insect infestation without using chemical sprays. One of them is to plant lemongrass as an intercrop. The lemon grass emits a smell that repels the moth that lays its eggs on the fruits and stems of the eggplant. The egg hatches into a larva that damages the fruit and other parts of the eggplant.

  • THE CULPRIT – The moth in photo is the culprit that lays its eggs on the fruits and shoots of the eggplant. The eggs hatch into larvae that damage the fruits and stems. The larva is the worm that is found inside the fruit making it not suitable for human consumption.

  • SMELL OF RADISH REPELS BORERS – When intercropped with eggplant, radish helps reduce eggplant fruit and shoot borer because it emits a chemical that repels the insect pest. Mungo and bush sitao are two other crops that can be intercropped with eggplant to repel thrips and green leafhoppers.

  • IMMATURE GINGER RHIZOMES – In Taiwan, some farmers harvest their immature ginger rhizomes. They are not as pungent as the fully mature ones but they make very good-tasting pickles. Filipinos should also learn to pickle the immature rhizomes for added value. Ginger candy and ginger tea are two other processed products from ginger that are popular. There are also similar products made in Vietnam.

  • ROBUST GINGER IN A PAIL – You can grow healthy and productive ginger in containers such as pails used in growing the plants in photo. The ginger plants which are just about three months old are very robust because of adequate organic fertilizer applied. Garden soil enriched with a half kilo of Durabloom organic fertilizer is the main reason why the plants are very healthy. They are expected to produce a good yield four months from the time the photo was taken.

  • LARVA FEEDING ON THE FRUIT – The worm in photo is the larva of the egg that was deposited in the fruit by the adult of the fruit and shoot borer. Infested fruit becomes not fit for human consumption. Excessive spraying with chemical pesticide can lead to chemical residue in the fruits which can be harmful to human health. Intercropping plants like radish, mungbean and bush sitao can help reduce pest infestation in eggplant.

    The most serious pest of eggplant is the eggplant fruit and shoot borer or EFSB for short. The larvae are what you often find as worms inside the fruit which make it unmarketable. Not many farmers know, however, that there are little known ways of preventing EFSB infestation without using chemical pesticide. This we have learned from Dr. Susan May F. Calumpang of UP Los Baños who is a member of the crop protection cluster of the college of agriculture.

    She and her colleagues have conducted experiments to find out how the insect that lays the eggs in the fruit and stem of the eggplant can be prevented from damaging the crop.

    One way is to intercrop radish with the eggplants. When the eggplant seedlings are planted in the field, radish seeds are also planted in a shallow furrow beside eggplant. In their study, they observed that the eggplant intercropped with radish were least attacked by EFSB. The effect of the radish was most apparent 9 to 10 weeks after planting, which is the time when the radish is harvestable. With this simple technique of intercropping radish, the farmer can greatly reduce EFSB infestation and he also has a bonus harvest of radish that he can sell.

    Dr. Calumpang says that radish has the repellent property that discourages the insect pest from laying its eggs on the fruits and shoots of the eggplant. She explains that plants emit certain odors that can affect the behavior of insect pests.

    Other pests of eggplant are thrips that cause browning of leaves and blemishes on the fruits. Another pest is the leafhopper which causes severe yellowing and crinkling of the leaves resulting in poor harvest. Damage of these pests can also be minimized by intercropping the eggplant with bush sitao or mungbean. The legumes attract the beneficial insects which feed on the leafhoppers and thrips, according to Dr. Calumpang.

    In another experiment, Dr. Calumpang and Rolando G. Bayot found that intercropping eggplant with lemon grass or tanglad is effective in reducing damage by EFSB, aphids and white flies.

    This technique, says Dr. Calumpang, provides the potential for increasing income of farmers while providing options for pest management which can reduce insecticide use. She adds, however,  that this cropping system of intercropping lemon grass with eggplant needs further evaluation on a larger scale as both economic and ecological conditions must be fully evaluated before an economic intercropping-based commercial production scheme can be recommended.

    Anyway, why can’t we ordinary gardeners do our own experiments? Let’s do it!

    There are other crops that can be protected by other techniques that don’t use any chemical pesticides. For instance, Dr. Calumpang in collaboration with Gideon Artes S. Burgonio have found that kakawate also repels green leafhoppers in rice. Leafhoppers are the main vector of tungro that inflicts serious damage on rice.

    In their experiment, they found that the smell of kakawate makes the male green leafhoppers unresponsive, hence mating is disrupted. The smell also affects the female leafhopper. It takes only 20 minutes for the female to alight on a rice plant without kakawate but when kakawate is present, it takes the female 40 minutes before it alights on a rice plant.

    Another endemic plant that repels green leafhopper in rice is the wild ginger known as Tagbak. Farmers in Infanta, Quezon often install cut leafy stems of the Tagbak in their rice fields to repel insects. While Tagbak repels the leafhoppers, it does not repel the beneficial insects, according to Dr. Calumpang.

    So there you are. There are simple means other than the use of chemical pesticides that can help farmers fight destructive pests of various crops.

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    • underthePhilippineSun

      on the fifth photo, “ROBUST GINGER IN A PAIL”, quoted “They are expected to produce a good yield four months from the time …. ”

      just wondering what a good yield means, where in fact the pail itself do NOT have ENOUGH AREA for the ginger rhizomes to spur…