Manit Luecha, former Director, Chainat Rice Seed Center, Chainat, Thailand,
Tiwaporn Sutthiwongse, Director of Evaluation, Office of Agricultural Economics, Thailand,
Monina Escalada, University Professor, Visayas State University, Leyte, Philippines, and
K.L. Heong, Principal Scientist, International Rice Research Institute, Los Baños, Philippines
In Central Thailand rice farmers have been suffering from floods and planthpper infestations. Record losses to floods (about 14% of the season’s crop) and BPH have been recorded in the last 4 years. BPH infestations had been threatening crops for the last 10 consecutive seasons, causing losses of about 2 to 3 million tons. In earlier focus group discussions some farmers were found to be reducing seeds, fertilizer and insecticides. These practices are similar to Vietnam’s 3 reductions program that has been cited by the minister to have successfully contained BPH problems in the Mekong. In October 2012 a wider survey was conducted to understand social impacts of pest outbreaks on farmers. We selected some key variables from the survey and compared the findings with an earlier survey carried out in early 2009.
In 2012, BPH populations in Chainat were high in March but subsided in August to below the population levels in 2008. In 2009, Chainat was heavily infested by BPH. Farmers were practicing prophylactic spraying using three insecticides which have known BPH inducing properties, like abamectin, cypermethrin or chlorpyrifos in the early crop stages. About 54% of their insecticide sprays were using these 3 insecticides. In the season of early 2012 in a study to understand the social impact of BPH outbreaks we found that only 25% of the farmers’ sprays were using these 3 insecticides applied routinely. In June 2011, TABA (Thai Agro business Association) and the Rice Department launched the “Stop use of cypermethrin and abamectin” campaign and this might have affected farmers’ insecticide choices. We also found that some of the secondary and tertiary pesticide retailers in the villages have stopped stocking cypermethrin and abamectin for fear that they can’t sell their stocks. In 2009, farmers were targeting about 51% of the sprays at leaf folders and “worms” while in 2012 farmers sprayed less for these defoliators, about 37% the sprays. The number of insecticide sprays in 2009 was 4.2 and in 2012 this was reduced to 3.6, about 14%.
There were significant changes in the rice varieties farmers planted. In 2009, 61% of the farmers in Chainat planted Pathum Tani 1 (PT1), 14% Suphan Buri 3 and 12% Chainat 1 while in 2012, 43% planted RD31, 28% RD47 and 16% RD41 with no one planting Chainat1 and only 2% planting PT1. Farmers in the area have been using PT1 for more than 10 years as this was the preferred variety of rice millers. It is said to have BPH resistance (maybe Bph1 or bph2 genes) but were vulnerable to hopperburn. The three new RD varieties were introduced as resistant varieties but it is difficult to determine what genes are present in them as there is no BPH resistance screening program in Thailand. In the pedigree of RD31, there were some parents with Bph1 (IR28), bph2 (IR36), Bph3 (Rathu Heenati) and bph4 (Babawee) and in RD 41 possibly bph2 (IR48) and RD47 possibly Bph1 (IR64).
Farmers in Chainat had higher yields in 2012 (5.7t/ha) than in 2009 (4.6 t/ha) when the BPH outbreaks were rampant. Between 2008 and 2012 all the farmers interviewed had their crops seriously damaged by BPH and more than 90% had hopperburn in the years 2009 and 2010. The average loss farmers experienced was about 0.6 t/ha.
Although farmers have adopted new varieties that probably have some “BPH resistance blood”, the genetic biodiversity remains low as was in 2009 with 87% growing 3 RD varieties. About 19% of the farmers think that BPH outbreaks were caused by varieties. The use of the 3 BPH resurgence insecticides (cypermethrin, abamectin and chlorpyrifos), although reduced still remains high constituting 25% of the sprays applied. There is increase in farmers mixing 2 or 3 insecticides into cocktails constituting another 33% of the sprays that contained the 3 chemicals. Thus sprays with one of the 3 resurgence causing insecticides consisuted as much as 57% of the total insecticide sprays applied. Many of them were mixed with other insecticides (9%), with fungicides (5%) and even with bio extracts (6%). Prophylactic spraying practices remain the norm and farmers continue to rely on pesticide retailers for advice. Pesticides are still being sold as FMCGs. Most crops are still vulnerable to BPH outbreaks. The reduction in BPH population in August might only be temporary and the potential of population build ups in later months of 2012 remains high as in the last 3 years. Heavy hopper attacks were beginning to occur in the northern provinces of Pitsanuluk, Chiangmai and Chiangrai in August and September and are likely to spread south in the next few months.