Rice farmers in Mwea have been advised to work together to reduce snail numbers in the area.
Manager, Mwea Research center, Vincent Koech, said farmers should conduct mass snail and egg collection campaigns, involving the whole community during land preparation and planting.
He said other farmers have also been counseled to keep fields drained as much as possible during the vulnerable stages of the rice plant (below 30 days) or transplant 25 -30 day old seedlings from low density nursery beds.
“Some natural predators like red ants feed on the snail eggs while ducks will eat young snails. Domestic ducks can be put into fields during final land preparation or after crop establishment when plants are big enough,” suggested Koech.
Farmers, he said, have also been informed of the possibility of handpicking the snails and crushing the egg masses. The official said it is best done in the morning and afternoon when the snails are most active.
“Place bamboo sticks to provide sites for egg laying that allows easy collection of snail eggs for destruction,” Koech advised.
He said farmers have also been introduced to the use of attractants (plants that attract snails) such as papaya and cassava leaves to make handpicking easier.
“We are educating the farmers on the characteristics of the Apple snails which have difficulty moving in less than 2 cm of water thus farmers should keep water level below the required level during the vulnerable stages of the rice plant.
He said in a situation of serious invasion of snail’s pests in a localized area, an option to practice closed season may be advisable. This will mean going a full season without a crop by making the land fallow.
“We are trying every method possible to control the increase of the snails’ population in Mwea, some farmers have even succeeded in the control by use of toxic plants such as Tobacco leaves which they place in strips across the field or in cannulates,” he said.
He said snails can invade fields from canals, rivers and reservoirs, thus, farmers should elect barriers where water enters and exits the field.
“Place a wire mesh on the main irrigation water inlet and outlet to prevent snail entry,” he instructed.
He said research has also shown that transplanted rice is less vulnerable than direct seeded rice. He said farmers should also go for multiple seedlings per hill to reduce missing hills from the snail damage.
Koech said currently there is no locally available chemical products that is registered for use as a molluscicide (chemical to manage snails).
There are more than 100 species of apple snail that exist, two species Pomacea canaliculata and Pomacea maculata, commonly known as Golden Apple Snails are highly invasive and cause damage to rice. Golden apple snails eat young and emerging rice plants cutting the rice stem at the base thus destroying the whole plant.
Apple snails are able to bury themselves in the mud and hibernate for up to six months, reemerging when water is reapplied to the fields.
Koech said farmers can be able to distinguish golden apple snails from native snails by checking the colour and size, with the pest appearing brown shell or golden pinkish or orange yellow.
He said they are bigger and lighter in colour compared to the native snails with their eggs appearing bright pink in colour.
“Then golden apple snails are so destructive that if no control measure is taken, one adult snail can completely destroy 1m squared of field overnight. This damage could lead to more than 50% yield loss,” Koech said.
By Irungu Mwangi