Reducing seed-densities in rice seedbeds improves the cultural control of apple snail damage

•We examined if poor attention to seedbed management could cause low adoption of cultural methods.•Delayed transplanting and transplanting more than one seedling per hill reduced snail damage.•Adherence to low sowing densities on the seedbeds improved these cultural control methods.•Low sowing densities also result in more robust rice hills.

Several cultural methods are known to reduce the densities of exotic apple snails (Pomacea spp.) and the damage they cause to rice in Asia. However, one aspect of seedling production – seedbed seed-density – has been largely overlooked and could compromise popular cultural control methods such as delayed transplanting. We conducted experiments to examine the effects of seedbed seed-density on hill survival in snail-infested paddy fields in the Philippines and to examine the interactions between seedbed seed-density and other cultural methods (delayed transplanting, 3 seedlings per hill and hand-picking). Seedbed seed-density determined seedling weight and stem thickness at the time of transplanting. Hill survival was highest where cultural methods (delayed transplanting and 3 seedlings per hill) were combined with low seed-density seedbeds (60–120 g m−2). Furthermore, reduced seedbed seed-density was directly related to increased hill biomass in field plots 32 days after transplanting. Hand-picking of snails together with delayed transplanting and 3 seedlings per hill eliminated hill mortality due to snail herbivory. Farmers adopting cultural snail control methods, but without adhering to low seedbed seed-densities risk increased losses due to snails because of poor quality seedlings. We suggest that seedbed seed-densities should not exceed 120 g m−2 with better results at even lower densities.