Wantana Sriratanasak, Dara Chettanachit and Orapin Wattanesk
Rice Department, Chatuchak, Bangkok Thailand
The brown planthopper (BPH) and the two virus diseases they transmit, rice grassy stunt (RGSV) and rice ragged stunt (RRSV), started infecting large areas in Central Thailand in July 2009. Both insect and diseases spread to all the provinces and several of the provinces, like Phitsanulok, Phichit and Kamphaeng Phet were suffered huge losses (Read about 30% of Kamphaeng Phet’s rice production destroyed by planthoppers). We are now beginning to see the infected areas declining in some provinces. In June there was about 25,000 ha (or only 6%) with BPH outbreaks compared to 379,000 ha in December 2009.
Although large areas in Suphan Buri, Sing Buri and Kamphaeng Phet were still heavily infected with the two virus diseases, damaged areas in other provinces, like Phichit and Chai Nat were very low in June. One reason for the decline was water shortage which prevented many farmers from growing the last crop. This had created a “break” in the outbreak cycles. In addition the government had also paid about US$ 28 million to farmers to delay planting.
Over the period from July 2009 to June 2010 of attacks of BPH and virus diseases, about 3.1 million ha of rice were seriously damaged and about 1.1 million tons of paddy lost. The government provided US$ 22 million in pesticide subsidies through the provincial budgets, US$ 28 million as incentives for farmers to delay planting and US$ 3.3 million for farmers to change varieties. The BPH in 2009/2010 had cost Thailand about US$ 275 million loss in export revenues and government spending of about US$ 60 million in subsidies, compensations, campaigns and control activities. The livelihoods of thousands of farmers were threatened as many suffered successions of crop losses and some of them went into debt. The government had also introduced a debt relief scheme to help farmers suffering losses from BPH attacks and drought.
Water shortage together with government efforts to delay planting had reduced cropping intensity which contributed to the decline in BPH outbreaks. In addition the government had also introduced seed subsidies to encourage farmers to switch varieties. In 2008 and 2009, farmers, in response to high rice prices, planted rice intensively with only 10 days break between crops. This had resulted in staggered planting and continuous presence of rice which by itself could introduce biodiversity and continuous supply of natural biological control. However, the intensive cropping was also done with intense input use of chemical fertilizers and pesticides, which deteriorated biodiversity and ecosystem services. In addition there was extremely low genetic biodiversity with 75% of the area planted to 2 varieties. In response to developing more sustainable ways to manage planthopper outbreaks, the government provided the Rice Department with an additional budget of about US$700,000 to apply ecological engineering and biotechnology techniques.
Many of the rice areas in Central Thailand would still remain vulnerable to BPH outbreaks as insecticide misuse continues due to farmers’ lack of knowledge and loss aversion attitudes. Farmers will continue to rely on pesticide retailers for advice and use resurgence causing insecticides (Read about insecticide selections making farmers vulnerable to hopperburn). There might be to be some increase in genetic biodiversity as farmers begin to use new varieties, but this change would be slow. When the water supply situation improves farmers might return to intensive cropping that might make some areas more vulnerable. However this would depend on rice prices in the next few months.