Agony for rice farmers as snails invade paddy fields

Monica Wambui assesses damage caused by apple snails on her farm at the Mwea Irrigation Scheme in Kirinyaga County. The snails hide in the mud and once rice is planted and irrigated, they emerge and feed on the plants.

Photo credit: Peter Chang'toek | Nation Media Group

What you need to know:

  • The snails grow up to 10cm in size and their bright pink eggs hatch 7-15 days.
  • Clutches can reach up to 1,000 offspring and they live up to four years.
  • John Kinyanjui, a field extension officer in Kirinyaga, says they are yet to get a chemical to curb the snails.

Margaret Wanjiru has been growing rice in Murubara, Mwea East, in Kirinyaga County for several years, harvesting thirty 100kg bags per acre.

Lately, however, the yields have been declining. At first, Margaret suspected diseases and the erratic weather conditions.

Well, apple snails turned out to be the unlikely suspect. The creatures that are ravaging rice on the scheme have become farmers’ worst nightmare.

“From 30 bags per acre, last season I harvested 13,” says Margaret who currently grows the crop on three acres. 

As many other farmers at the scheme, she began noticing the snails last year. “The eggs were very tiny and pink. We did not know they were snail eggs. We planted the off season rice last December and during harvesting, we noticed the number had surged.”

According to her, the snails hide in the mud and once rice is planted and irrigated, they emerge. They then feed on the plants. “They cut them like caterpillars. They float on water, hang on rice plants as they feed on the stems.”

“When you drain away the water, they go under the mud or hide in their shells,” adds the farmer.

The apple snails thrive in wet areas and rice paddies are their favourite, according to experts.

Yet to get a chemical

Farmers have now employed people who pick the snails manually at a fee. They pay the snail pickers Sh30 for every 2kg plastic container. 

Margaret says one can pick up to 50 containers of snails per day, which translates to Sh1,500 per day.

"Sometimes we are charged up to Sh50 per container especially after planting.” Monica Wambui, another farmer at the scheme, says snails are a great problem. “We don’t have pesticides to control them. We need government to assistance.”

The snails grow up to 10cm in size and their bright pink eggs hatch 7-15 days. Clutches can reach up to 1,000 offspring and they live up to four years.

Carol Mutua from the Department of Crops, Horticulture and Soils, Egerton University, says farmers should ensure that they clear vegetation and weeds surrounding rice fields as they act as breeding grounds for snails.

“Screens can be put in water inlets to prevent entry of the snails,” she says, adding that hand picking of both adult snails and eggs can also be done using nets.

“Place a copper wire or strip above the water level. Copper is toxic to snails,” adds the expert.

John Kinyanjui, a field extension officer in Kirinyaga, says they are yet to get a chemical to curb the snails.

Jackline Njogu, the Kirinyaga County Agriculture executive said she was not aware of the problem.

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