Golden Apple Snail: How to Spot It and Stop It in Your Palay

Farmers care because the snail eats young plants from the base, and a cut seedling does not grow back. It can reduce yield by up to 40 percent. Older rice is safe, because plants about 30 days old are thick enough to resist it. That is why the early days matter most.

How to Identify Golden Apple Snail

Look for a round, brownish snail the size of a small fist in the water. Look also for bright pink egg masses stuck on stems, pilapil and posts just above the water. Missing hills in rows, with cut leaves floating, point to the snail. Damage from rice whorl maggot leaves the seedling standing, while the snail removes it.

• Seedlings are cut at the base and the leaves float on the water.
• Rows of hills are missing, often starting near the irrigation inlet and the edges of the paddy.
• Bright pinkish red egg masses cling to rice stems, pilapil, canal walls and posts.
• Snails of different sizes sit in the water and in the mud, mostly in the early morning and late afternoon.
• Damage stops once the rice is about 30 days old, because the stems have grown thick.

How Golden Apple Snail Hurts Your Palay

The snail can cut yield by up to 40 percent. It can eat a whole young paddy overnight. A study found that one snail can damage up to 19 percent of the young plants in a square meter. The first 15 days after transplanting are the most dangerous.

Replanting costs seed, labor and time, and a late stand misses the best weather. That is why prevention is cheaper than repair. Count the snails and egg masses in the paddy before you transplant, and write the numbers in a note for the lot.

How to Control Golden Apple Snail

1. Prepare the land well and remove snails by hand in the morning and late afternoon. Hand picking works best for large adults, which ducks do not eat.
2. Dig small, deep strips or canals along the paddy. Place leaves of gabi, papaya or banana, or gugo, sambong, calamansi or makabuhay, so snails gather there for collection.
3. Scrape off the pink egg masses from stems and pilapil and crush them, since they hatch in 7 to 14 days. Screen tapping and staking are physical methods too.
4. Keep the water shallow, about 2 to 3 centimeters, starting 3 days after transplanting. Drain the field from time to time. A saturated field, with no standing water, gave 99 percent seedling survival in transplanted rice. Snails cannot swim there.
5. Herd ducks into the fields after harvest and until final land preparation. Ducks eat the young snails and the flesh of broken ones. Red ants and long horned grasshoppers also eat the eggs.
6. Level the field well, so the water stays even and no deep pockets of water hold snails.

When a Spray Makes Sense

A molluscicide comes last, after hand picking and water control. Controlled irrigation costs less than the P400 to P500 per hectare that farmers spend on synthetic molluscicide. If you still need one, use only a product registered with the FPA. Follow the label and the safety advice, since these chemicals can harm fish and ducks.

The timing and the choice both matter. Treat only where the snails will cause damage, and do it the day after transplanting, while the seedlings are smallest. Then pick the active ingredient by your water. Where irrigation runs strong and is hard to control, or sudden rain is likely, use metaldehyde. Where water is scarce and no rain is expected, use niclosamide. Apply either one only on a field with standing water, in the morning or the late afternoon. Our guide on when to spray rice pests has the timing for the rest of the season.

Keep It Out Next Season

• Put wire or woven bamboo screens on the water inlet and outlet to keep snails and hatchlings out and to trap them.
• At the last harrowing, dig small canals about 25 cm wide and 5 cm deep along the edges. Snails gather there when you drain.
• Keep the water at 2 to 3 cm from 3 days after transplanting, and drain now and then. Level the field so no deep pockets stay.
• Where snails are many, transplant older seedlings, about 25 to 30 days old, with stems too thick for the snail.
• Hand pick snails in the morning and late afternoon, set bamboo stakes for them to lay on, and crush the pink egg masses.
• Lay gabi, papaya or banana leaves in the canals as bait, then collect the snails that gather under them.

Natural Enemies and Biological Help

• Herd ducks into the field after harvest until the last harrowing, and again once the rice is past the danger stage. They eat young snails.
• Red ants and long horned grasshoppers eat the eggs. Pick the big adults by hand, since ducks skip them.
• Picked snails make duck or pig feed, or food when well cooked.

Not Sure What You Are Seeing?

Take a clear photo of the insect, the damage and the whole plant, then ask Anee, the smart farm technician in anee.io, in Tagalog or English. Anee tells you what it most likely is and what to do at the age of your crop. You can also put your scouting days on the cropping calendar, so the team knows when to walk the field.

Questions Farmers Ask About Golden Apple Snail