Rice farmers in the Mwea region of Kirinyaga County have been given tips on the management of the snails threatening paddy rice production. The programme is meant to teach farmers how to deal with the snails.
This comes at a time when the Golden Apple Snails are threatening rice production in the rice belt. The snails first appeared in March last year, but farmers thought they were the usual snails found in the paddies. They ignored the strawberry-red eggs that clung to the growing rice straws, unaware that this was a disaster in the making.
Mwea-Tebere area is the most affected by the Golden Apple Snail, which were first reported in March 2020. So far, the voracious snails have spread to about 780 of the 26,000 acres of the scheme.
Mwea Rice Irrigation Scheme, the largest in East and Central Africa, produces about 114,000MT of paddy rice worth Ksh8.2 billion, annually and 80 per cent of the processed rice is consumed locally.
This snail has become is a major concern in the country given that one adult snail can destroy one square meter of a field overnight and can lead to more than 50 per cent yield loss.
Eggs take seven to 14 days for them to hatch, 15 to 25 days to grow into a small snail, and 45 to 59 days to transition into an adult.
While the apple snail can exhibit a very short life cycle of fewer than three months in areas with high temperatures, it can live for more than two years in swampy and cold areas.
During an interview with the Smart Farmer magazine, Mr Vincent Koskei, the centre manager at the Mwea Irrigation Agricultural Development office, noted that there are more than 100 species of apple snails. However, two Pomacea canaliculata and Pomacea maculata, commonly known as Golden Apple snails, are highly invasive and cause serious crop damage.
“The rice farmers have now been equipped with the knowledge to distinguish between the Golden Apple Snails and the native ones through their colour and size,” he said.
“Golden Apple Snails have a muddy brown shell and golden pinkish or orange-yellow flesh. They are bigger and lighter in colour compared to native snails with their eggs appearing bright pink.”
How to control the snails
- The snails can spread through irrigation water canals, natural water distribution pathways, and during flooding in the heavy rainy seasons. However, farmers should note that when there is no water, Golden Apple Snails bury themselves in the mud and can hibernate for up to six months, re-emerging when water is re-applied.
- Use barriers where water enters and exits the field by placing a wire or screen at the main irrigation water inlet and outlet to prevent snail entry.
- The snails attack direct wet-seeded rice and transplanted rice up to 30 days old. Once the rice plant reaches 30 to 40 days, it becomes thick enough to resist the slimy pest. The critical time to manage golden apple snails is during land preparation and crop establishment or planting, specifically the first 10 days after transplanting and or during the first 21 days after direct wet seeding.
- Plant healthy and vigorous seedlings because transplanted rice is less vulnerable than direct-seeded rice. They should also raise seedlings in low nursery beds, and delay transplanting to reduce missing hill snail damage***what kind of damage is this…pls explain***. After transplanting, the rice crop is generally resistant to snail damage.
- To decimate the rising snail numbers, the communities should conduct mass snail and egg collection campaigns during land preparation and planting.
- Farmers can also handpick and crush the egg masses. This is best done in the morning and afternoon when the snails are most active.
- Farmers are also advised to place bamboo sticks to provide alternative sites for egg-laying that allow easy collection of snail eggs for destruction.
- The other control method is to introduce domestic ducks in the fields during final land preparation or after crop establishment when plants are big enough, 30 to 35 days after transplanting.
- Apple snails have difficulty moving in less than 2cm of water. Therefore, farmers can control their spread by keeping the water level below the two-centimetre level during the vulnerable stages of the rice plant.