A RECENT study by researchers from the Philippine Rice Research Institute (PhilRice) revealed that growing azolla with rice can minimize the damage caused by golden apple snail (GAS) to the crop.
Lead researcher Dindo King Donayre said growing azolla can divert the appetency of the GAS away from newly established rice.
“The amount of missing seedlings is significantly reduced by up to 89.2 percent per square meter, with an
average of 60 snails per square meter,” Donayre said in a statement.
The GAS, popularly known as “golden kuhol,” is one of the major rice-pest problems in the Philippines.
Data from PhilRice showed that yield losses caused by this pest reached 40 percent, resulting to huge production loss. The research institute said their most “vulnerable” targets—as a source of food—are 15-day-old transplanted rice seedlings and four- to 30-day-old direct seeded rice.
PhilRice said GAS can lay up to 1,200 eggs per month. To control this pest, most farmers use synthetic molluscicides, which are expensive, can also affect non-target organisms and are harmful to the farmers themselves.
Meanwhile, azolla—duckweed fern, fairy moss or water fern—is known for its nitrogen-fixing capability and is widely used as a biofertilizer, which lowers farmers’ expenses on synthetic fertilizers.
“As a free-floating aquatic plant, it also serves as an alternative food of GAS in the absence of rice,” the PhilRice said. The PhilRice added during the study, azolla was introduced to the rice field 10 days after the transplanting of the crop. GAS were also placed at different population levels throughout the experiment area. Data on missing rice seedlings were gathered daily for 7 consecutive days.
“At varying water levels and GAS population per square meter, we noted a significant decrease of missing seedlings,” Donayre said.
The decrease ranged from 84.3 percent to 89.2 percent at a 1-centimeter water level, while at 2 to 3 centimeters, the rate of decrease ranged from 65.3 percent to 77.6 percent—all from 30 to 90 GAS population per square meter.
“It is a natural way of GAS management. Aside from being an alternative method to nutrient management, growing of azolla is also an effective, economical, and environment-friendly way of managing GAS,” Donayre said.