Kukiat Soitong and Wantana Sriratanasak, Rice Department, Bangkok, Thailand
In the years of 2009 and 2010, planthopper outbreaks threatened rice production in parts of Thailand, Philippines, Indonesia, India, Bangladesh, Malaysia and China. Light trap records from Chainat province showed that planthopper populations increased by more than 100,000 folds. Rice production in Thailand lost more than a million tons. The Office of Agricultural Economics reported a total production loss value of US$ 51.2 million for the 2010 dry season. Since planthopper problems are insecticide induced, the Rice Department working with IRRI and TABA (Thai Agro Business Association) launched a ban of cypermethrin and abamectin, two commonly used resurgence causing insecticides in rice.
The floods in many parts of the Central Plains halted rice growing for several months. Many of the natural enemy habitats were submerged and thus new rice cultivations can be vulnerable to planthopper invasions. Vulnerability to planthopper outbreaks is further increased when fields are sprayed in the early season with insecticides, especially those that are the resurgence causing, like cypermethrin and abamectin. In early February of 2012, outbreaks were reported in Chachoengsao where planthoppers had damaged more than 2000 hectares. Reports of outbreaks surfaced from the Angthong and Suphan Buri and about 1,000 hectares were affected (Nation News Channel on 7 February.
On 9 February 2012, together with IRRI scientists, Drs Bas Bouman, Division Head and K.L. Heong, Principal Scientist, we visited Ban Sue in Pathum Tani. About 20 farmers in the village were experiencing hopperburn. One farmer, Khun Chan, said that he had sprayed cypermethrin seven (7) times and when hopperburn started, he changed the insecticide and sprayed at 2 day intervals. A women farmer described how, about a month ago, BPH first invaded her home and subsequently her field had hopperburn. She had also used cypermethrin early in the season.
Although the banning of cypermethrin was announced in June last year, posters have been distributed and many farmers know about the ban, cypermethrin continues to be used by farmers. Khun Chan said he knew that cypermethrin is not to be used in rice, but the local pesticide retailer had recommended the product and he followed the advice of the retailer. He further added that the retailer should be the one to blame as he depended on his advice. This illustrates the urgent need for Rice Department to intensify the Sustainable Planthopper Management Program and work together with TABA and the pesticide regulators to prevent the use of early season spraying and resurgence causing pesticides.
It seems inevitable that planthoppers will continue to threaten rice production in Thailand this year. Although comprehensive programs and campaigns have been launched in attempts to prevent outbreaks, most of the activities have not penetrated sufficiently. At the grass root levels, farmers continue to be victims of wrong advice from untrained retailers. Pesticides continue to be marketed as FMCGs in violation of the FAO Code of Conduct, misused in multiple mixtures and as prophylactic sprays. Fixing the root causes of insecticide misuses and planthopper outbreaks, is likely to take some time and strong political will.