Patchanee Chaiyawat, Phra Nakhon Si Ayutthaya Rice Research Center, Rice Department, Thailand,
Chairat Channo, Chainat Rice Research Center, Rice Department, Thailand and
Wantana Sriratanasak, Bureau of Rice Research and Development, Rice Department, Bangkok Thailand
While Vietnam, now the world’s second largest rice exporter ,is announcing that they will increase rice production and export (Vietnam Business) and expected to reach 2.14 million tons this year. Thailand the world’s leading rice exporter, on the other hand is curbing rice production (Bizweek) . One of the reasons that Thailand’s rice production is expected to decline is the abundance of outbreaks caused by the brown planthopper (BPH). Vietnam, on the other hand, has very little outbreaks of this pest in the last 4 years and has been producing bumper crops in the last 2 years. A Bangkok Post news item reported that Vietnam’s “Three Reductions, Three Gains” program is one factor that enables Vietnam to increase rice production. The program has become a national policy motivating farmers to reduce seed and fertilizer rates and to avoid using any insecticides in the first 40 days after sowing thus reducing insecticide sprays. IRRI scientists in collaboration with Vietnamese scientists introduced this program in 2003, is now adopted by most farmers. Farmers practicing Ba Giam Ba Tang, the local name for the program, reduce their insecticide sprays by 13 to 33% (Huan et al 2008).
The light trap records from Chai Nat Rice Research Center have shown marked increase in hopper catches in March similar to trends in 2009 and 2010. Two more periods of large increases in July and November will likely to follow. In pre rice crisis 2008, planthopper populations had been much lower. Rice prices were about US$ 320/ton in late 2007 rising to a peak of US$1015 in April 2008 (more than 3 fold increase) and prices are now around US$520 (or 1.7 folds) which is still substantially higher than pre crisis years. High rice prices not only drive farmers’ enthusiasm to intensify production, they also stimulate related commercial activities, such as pesticide advertising, promotion and marketing. Insecticide imports in Thailand rose 1.7 times during this period.
Beginning in March 2011, huge populations of the BPH infested rice fields in Ayutthaya, Chai Nat, Suphan Buri, Ang Thong, Sing Buri and Pathum Thani provinces destroying thousands of hectares. In March 2011, damages reported from 11 provinces affected 104, 000 ha and further hopper outbreaks would seem inevitable. Numerous farms in the northern provinces, like Pitsanuluk, are now heavily infested. Most rice areas in the Central Plains continue to remain vulnerable to hopperburn because of intensive cropping, continuous planting of a few varieties that BPH has become adapted to, high seed and fertilizer rates and high use of prophylactic insecticide applications. Perhaps among the vulnerability factors insecticide misuse is the major contributor to the crop yield instability. Most farmers continue rely on the local pesticide retailer for advice and were told to mix insecticides with BPH resurgence causing properties, like cypermethrin, abamectin and chlorpyrifos with herbicide sprays early in the crop season. In Chai Nat these 3 insecticides accounted for 62% of farmers’ sprays last year (Manit).
The BPH continues to threaten rice production in Central Thailand because of rampant insecticide misuse. Most farmers spray cypermethrin and abamectin, which have toxic high effects on bees and hymenopteran parasitoids early in the crop season thus destroying the crucial egg parasitization ecosystem service that can prevent invading BPH from multiplying exponetially into outbreak proportions. In Thailand pesticides are sold like FMCG (fast moving consumer goods) that rely on advertising to create emotional buying, and thus creating the rampant misuse. In order to reduce the threat of this insecticide-induced pest problem, government will need to seriously consider the banning or restricting the use of insecticides that have resurgence causing properties. Wantana (2010) provided a list of such insecticides.
Farmers described to the TV reporter here and here that they started spraying insecticides at 3 to 7 day intervals after hearing about BPH outbreaks in the neighboring province. Their crops turned brown and completely destroyed in less than a week after the spraying.
Huan, N,H, H.V.Chien, P.V. Quynh, P.S Tan, P.V. Du, M.M. Escalada , and K.L. Heong. 2008. Motivating rice farmers in the Mekong Delta to modify pest management and related practices through mass media. J International Pest Management, 54: 339 — 346.
Wanatana Sriratanasak. 2010. Brown planthopper: A formidable rice insect pest in irrigated rice growing areas and new concept of its management. Thai Rice Research Journal, 4, 72 – 82.