Controlling golden apple snails that damage rice crops.
(Baonghean)The golden apple snail (GAS), originating from Central and South America, was imported into Vietnam in 1988 for the purpose of farming as food. However, for agricultural production, the GAS is one of the 100 most dangerous species that the world is seeking ways to eradicate. The Ministry of Agriculture and Rural Development is advising all localities nationwide to find all possible methods, from manual to biochemical, to completely eliminate this harmful organism.
Currently, golden apple snails are proliferating in many rice-growing areas of our province. Almost all districts and communes in the province have reported the emergence and development of golden apple snails. According to reports from many localities, the snail population has been and is showing a strong tendency to increase during the current spring rice crop, causing significant damage in many areas of Nam Dan, Hung Nguyen, Nghi Loc, Anh Son, Do Luong, etc.
A female rice stem borer can lay 1,000 eggs in a month. The eggs hatch after about 12-14 days, and within two days of hatching, the larvae are able to move and forage for food. Rice stem borers are voracious eaters, feeding continuously day and night. In rice fields, they feed in clumps, concentrating their consumption in low-lying areas, young rice plants, newly transplanted rice, and direct-seeded rice. In drought conditions, where the water dries up, rice stem borers can bury themselves deep in the soil and remain dormant for months without dying.
Therefore, control measures to eradicate rice blast and protect rice crops from damage need to be carried out synchronously, continuously, and with a combination of manual methods and biological and chemical control measures.
Manual harvesting is the cheapest and least harmful method to the environment. Local authorities should launch a campaign to encourage all citizens to go to the fields to catch and exterminate the giant freshwater snails. The snails should be crushed to extract their meat for human consumption, poultry, and pig feed. The snail eggs, which are laid in clusters and are bright red and easily visible, should be crushed or crushed. This work must be carried out regularly and continuously for many days and months to completely eradicate them. In cases where the number of giant freshwater snails is too large, in addition to manual harvesting, we can use nets to block the water source to prevent the snails from moving and to stop them from concentrating in one place for extermination; or dig trenches 25-30 cm deep so that the snails move into the deep pits for easy harvesting. Another very effective method is to scatter cassava leaves, neem leaves, banana leaves, jackfruit fibers, etc., at several points around the edges of rice fields and ponds to lure the snails to feed and then exterminate them.
In addition to the manual methods of catching and eradicating OBV mentioned above, biological methods can be combined, such as: raising fish in rice fields, especially carp, and raising ducks in rice fields.
Using chemical methods to eradicate rice blast disease (OBV) is a last resort. This is because it pollutes the water environment and is detrimental to many other organisms, including humans. Therefore, chemical methods should only be applied when the number of OBV reaches an average of 3 or more per square meter, or when 10% of the rice tillers in the field have been damaged.
When using chemical pesticides to eradicate OBV, use a specific pesticide and carefully read the instructions on the packaging. Many types of pesticides are available to kill OBV, but the most common are:
- The active ingredient, metallaldehyde, destroys the mucus cells of snails, causing them to dehydrate and die. The dosage is 250-300 grams/ha, applied evenly 5-10 days after direct sowing or transplanting rice, and the water must be drained before application.
- The active ingredient, Niclosamide, inhibits the exchange of oxygen and carbon dioxide. The recommended dosage is 200-250 grams per hectare, diluted in 160 liters of water for spraying. It is best to maintain a shallow water level in the field during spraying.
When using chemical pesticides to kill OBV (Oriental Black Liver Virus), the following should be noted: Do not spray on rice fields without embankments to ensure good water retention, and only on fields that are not used for integrated fish farming.
Doan Tri Tue