Current status of biological control of paddy weeds in Vietnam

Rice is a staple food in Vietnam and accounts for > 7.7 x 10(6) cultivated ha, which provide 35.5 x 10(6) t of rice, of which 4.2 x 10(6) t were exported in 2004. The enlargement of the cropping area and the enhancement of rice yield have rapidly increased the amount of agrochemicals, including herbicides, in crop production in Vietnam. From 1990-2003, the percentage of herbicides in total pesticides has increased approximate to 10-fold to 30.2%. In addition, the improper use of herbicides caused environmental hazards, unsafe agricultural products, and human health problems. Biological management integrated with traditional weed control techniques might help to reduce the dependence on synthetic herbicides and build eco-friendly, sustainable agricultural production in Vietnam. This paper reviews the efforts in establishing a strategy for biological management of weeds that was conducted in recent years by Vietnamese weed scientists. This has included cropping system management, water and soil management, integrated pest management, and utilization of plant allelopathy as major components of the strategy. Many plants with strong allelopathic potential can be a source for biological weed suppression and soil fertility improvement. The utilization of allelopathic properties in rice might also help to provide new rice cultivars with weed-suppressing characteristics.