What’s more, the fruits are free from insecticides. Damages by fruit flies and worms prevent farmers from attaining the estimated income of P300,000 a hectare, as damaged fruits could not be sold.
Researchers of PhilRice (Philippine Rice Research Institute) led by Dr. Hoai Xuan Truong, a research fellow from Vietnam, ampalaya or bitter gourd is a favorite host of fruit flies and worms, which are also the most critical pests of cucurbits. Adult female flies and butterflies lay eggs on young fruits, resulting in poor fruit development. Young fruits at 6 to 10 days old are more susceptible to these insect pests.
Although fruit bagging is one of the common methods of preventing damages on the fruits, Truong said the bagging materials used by farmers are not very effective. Traditionally, farmers have been using plastic bags or newspapers to protect ampalaya fruits from fruit flies.
The PhilRice researchers observed, however, that small plastic bags cause fruits to curl and crack. On the other hand, newspapers cannot cover the fruits completely, thereby allowing pests to enter through the open spaces. Moreover, fruits covered by newspapers are pale because sunlight is blocked from radiating to the fruits.
Results of Truong and company revealed that net bagging with fiberglass mesh cloth, which is usually white, is the most effective, easiest, and quickest way to prevent damage on the fruits. Various bagging materials were compared in their study.
Truong said net bagging is extremely necessary if the pest population is high. Thus, he advised farmers to use light traps to monitor the pests and determine the level of infestation. A catch of 30 flies per trap each week would signify a severe infestation.
For best results, net bagging with white fiberglass mesh cloth should be done at the flower stage. The bag should measure 6 inches x 10 inches with a 5-inch opening at the top so that the flower could easily be placed inside.
Tighten each bag around the pedicel or flower stalk using an ordinary clip for clothes. Leave the net bags until the flowers develop into marketable fruits.
Truong said net bagging increased the number of marketable fruits to as much 95 percent and, hence, considerably increased the farmer’s net income. The fruits are straight, indicating the absence of worms inside.
Besides being easy and quick to do, net bagging is a very cheap control strategy since the bags can be reused for at least six planting seasons or up to three years. Moreover, this method could save expenses on insecticides and helps prevent health and environment hazards. — S. Ma. Pablico & A.A. Kindipan