Hopperburn in Myanmar in 2009

In March 2009 about 8100 ha in Bogalay were heavily infested by BPH and a loss of 20,900 tons was estimated. This year in February an area of about 10 ha was completely destroyed by BPH.  Farmers in the area started spraying their fields with cypermethrin and diazinon.  It is likely that these farms suffered hopperburn because they were vulnerable at the time of a sudden mass displacement of BPH migrants.  Are these BPH outbreaks related to the outbreaks in Central Thailand? In 1998 about 18,200 ha in Khayan and Thongekhwa, Yangon Division were infested and this was also during the time of the BPH outbreaks in Central Thailand in 1998.  The Central Plains in Thailand is less than 600 km from Yangon and there are probably prevailing westward winds. There is however insufficient data in Myanmar to explore this relationship further.

Bottles of insecticides used in Myanmar found in outbreak areas

The Myanmar Agriculture Service (MAS), the Myanmar Rice Industry Association (MRIA) and IRRI recently organized a one day workshop in Yangon to explore for ecological solutions to restore biodiversity and ecosystem services to prevent future BPH outbreaks.  Farmers in Myanmar (about 58%) believe that BPH causes the most serious losses.  The tri partite workshop was initiated by Dr Larry Wong, advisor to MRIA, to introduce ecological engineering techniques to Myanmar. MRIA, a newly established organization charged with the responsibility of “bringing Myanmar back to her glory days as a major rice exporter” (Yewin Aung, MRIA Secretary General).

Group picture of workshop

About 90% of farmers in Myanmar use insecticides and in the last 5 years insecticides used in rice has increased about 4 folds.  Many of the insecticides used were resurgence causing like deltamethrin, cypermethrin and furadan.

Insecticides used by the Ministry of Agriculture and Irrigation (MOAI) for paddy. Source – Department of Agricultural Planning, MOAI 2009.

Dr. KL Heong describing the features of a farmer experiment on ecological engineering with farmers, Dr. Orapin (Rice Department) and Khun Manit (Chainat Rice Research Center), Nakhon Nayok province.

In mid-August 2010, we traveled more than 1,500 km through the central region, stopping in Nakhon Nayok, Uthai Thani, Chainat, Ang Thong, Phitsanulok, Phichit and Ayuthaya provinces talking to farmers about their rice crop and the changes they have made to their cultural management to deal with the BPH problem and to explore their attitudes toward ecological engineering.

Uthai Thani farmers Wanna Thongma (center) and Saangsri Samransuk (right) discuss with Dr. Patchanee their crop loss from the BPH outbreak.

In mid-August 2010, we traveled more than 1,500 km through the central region, stopping in Nakhon Nayok, Uthai Thani, Chainat, Ang Thong, Phitsanulok, Phichit and Ayuthaya provinces talking to farmers about their rice crop and the changes they have made to their cultural management to deal with the BPH problem and to explore their attitudes toward ecological engineering.

Uthai Thani

Last season, some farmers in Uthai Thani had grassy stunt virus which wiped out their rice crop. Those who planted Supan Buri 60 experienced BPH outbreak which pushed them to shift to RD31. In last year’s outbreak, some farmers lost as much as 60,000 – 70,000 baht for which they paid 7.5% interest to the Bank of Agriculture and Agricultural Cooperatives (BAAC).

Among those farmers was Wanna Thongma, 35, who has been farming for 10 years in Uthai Thani province. During last year’s BPH outbreak, she lost 4 tons from her 2.92 ha planted to Suphan Buri 3. She applied insecticides 12 times but could not remember the product names of the chemicals distributed free by the province, as part of the government’s response to the BPH outbreak. She said they sprayed every 10 days and the BPH persisted and they would follow it up with another spray after 4 days. She admitted that the 12 insecticide applications did not help solve her BPH problem.  Although they also consumed the rice they planted, farmers in the area did not seem to worry about pesticide residue. Wanna thought that the BPH outbreak was caused by higher temperature. She recalled an outbreak many years back which they quickly solved with 1-2 sprays.

Buprofezin distributed by the government last year

Her production cost for her entire rice farm was THB 30,000 (US$ 968) but she lost a net amount of THB20,000 (US$645). She said another woman farmer spent THB 70,000 to operate a 27-rai (4.32 ha) rice farm but lost more than THB 50,000 (US$1,612).

Her neighbor, Saangsri Samransuk, has been into rice farming for  the past 20 years, tilling a total of 36 rai (5.76 ha), 9 rai of which is rented at THB 1,500/rai/year or a total yearly rent of THB 13,500 (US$435). She planted RD31 this cropping season but she believes that planting RD31 is not sufficient to avoid BPH attack.

Rice millers in Uthai Thani give the same price to Pathum Thani 1 and RD 31 if the truck is not full. If the truck is full, they give a higher price for Pathum Thani 1. Suphan Buri 3 sells at a price range of THB6,000 to 6,600/ton.

It was the local extension technician, who advised both women farmers to apply insecticides to control BPH. They were trained and received free insecticides from the government and also bought the same type of insecticides from the shop. The pesticide seller also recommended particular insecticides. To control BPH this season, they plan to flood the field to submerge the BPH eggs. They came up with this idea themselves and will explore if it works.

This season, both Wanna and Saangsri have already applied 3 insecticide applications – first at 40 days after transplanting with cypermethrin to kill the worms, the second was buprofezin for leaffolders, and the third was also buprofezin for BPH.  They thought that without spraying insecticides the rice crop will have stunted growth, it will turn yellow and they will have nothing to harvest.

Several years ago, both women farmers attended the IPM farmer field school where they were taught pests, predators, bio-extracts, the right chemical to use for BPH, not growing rice successively and reduce the seed rate to 94 kg/ha However, when they applied bio-extracts in their field, they found these to be useless as the planthoppers from other fields migrated to their fields. Bio-extracts, they said, could not compete with chemicals.

Phitsanulok

Phitsanulok farmers Napasin Khonsangaim (left) and Sirm Riengchay (center) relate how planting a resistant variety will help them avoid an outbreak.

A village leader in Wangpikun, Wang Thong district, Napasin Khonsangaim, 37, has been cultivating a 16 ha-rice farm for 15 years. Farmers in the area practice staggered planting with irrigation water drawn from natural sources for which they pay the local government the cost of electricity to pump the water. In the dry season, the cost is $40.32/ha and $30.24/ha during the rainy season.

Napasin recalled that the BPH outbreak last year was severe and realized that spraying did not solve the problem. He lost only 20% of his rice crop because he had planted Phitsanulok 2, a resistant variety. Where he used to harvest 5.31 t/ha or a total of 85 tons in a normal cropping season, he only managed to generate 70 tons from his 16 ha.

Another farmer, Sirm Rienchay, 65, who operated a 4.96 ha rice farm, had planted Chainat 1 rice variety and lost nearly 70% of his expected production.  Before the outbreak, he used to harvest up to 27 tons, but during the outbreak, he yielded only 9 tons. He said that farmers in their village liked to plant Chainat 1 because it has better grain quality. Chainat 1 fetched a price of THB7,300/ton while Phitsanulok 2 was sold at THB6,900/ton.

When the BPH outbreak struck, both farmers applied insecticides 5 times, using chemicals recommended by pesticide sales agents and sellers and other farmers who had used them before and found them to be effective. The first spray was cypermethrin to control thrips; second, were abamectin and chlorpyrifos for stem borers and case worms; third, buprofezin for BPH; fourth and fifth were dinotefuran for BPH.

Napasin believed that the BPH outbreak was caused by continuous rice planting while Khun Sirm thought it had to do with the cooler temperature brought on by the rainy season. Both acknowledged that the amount of yield loss depended on the rice variety they planted. Chainat 1 suffered 30% loss. Other farmers, they noted, had also lost heavily because the sprayed at the wrong time and might have used the wrong insecticide.

Both farmers recalled that about 3 years ago, a BPH outbreak occurred twice. They found that only those areas planted to Chainat 1 were damaged while those with Suphan Buri 1, Suphan Buri 2 and Phitsanulok 2 were not affected by the outbreak. Last cropping season, to solve his grassy stunt virus problem, Khun Sirm applied both organic and inorganic fertilizers but it did not help. He lost his 1-6-ha rice crop. Napasin observed that grassy stunt virus occurs when the soil texture is sandy clay which characterizes the soil in Phitsanulok province. It is prone, he said, to sheath blight and dirty panicle disease.

To avoid an outbreak this season, Khun Sirm shifted to planting Phitsanulok 2 and both farmers reduced their insecticide use frequency to 2 to 4. They are optimistic that there will be no outbreak this season. Napasan pointed out that a BPH outbreak usually occurs at the early crop stage (20 DAS) but their current rice crop is already at the last growth stage and there has been no BPH attack yet.

Napasin and Khun Sirm are seed producers for the Phitsanulok Rice Seed Center. As seed producers, they must make sure that there are no mixtures and no weed contaminants in their rice seeds.

Phichit

Rice seed bed in Phichit

In Bangphai village, Bangmulnak district, Wanna Chumpunute, 54, has been managing a 4.48 ha-rice farm for 35 years. She used to grow Chainat 1 but had to shift to Tathum 80 (RD31), a rice variety recommended by the Phitsanulok Rice Research Center. Using the parachute transplanting method, Wanna would usually harvest 23 tons. However, during the BPH outbreak last year, she got only 5 tons, representing almost 80%  crop loss. For this loss, the government gave farmers 1,000 ml isoprocarb for every 10 rai (1.6 ha). She said the farmers’ bank, BAAC, helped farmers by allowing them to delay their loan payments for a year without interest.

Phichit farmers Wanna Chumpunute (left) and Panida Copachan (right) describe their insecticide use during the BPH outbreak.

Panida Copachan, 32, has been farming for 18 years using a transplanting machine to establish her rice crop. She used to plant Chainat 1 but has now shifted to RD31, a government-recommended resistant variety. Panida used to harvest 23 tons from her 4 hectare farm but when the BPH outbreak struck, she got only 15 tons. She believed that her yield loss was not substantial because transplanting made it easier for her to manage the planthoppers.

During the BPH outbreak, Panida sprayed 5 times, mostly dinotefuran and buprofezin to control the BPH. On the other hand, Wanna applied insecticides as many as 7 times. Her first application was abamectin and she could not recall the names of the 6 other insecticides her husband applied. To choose the chemicals to apply, they checked the leaflet that they had obtained from training, consulted the Phitsanulok Rice Research Center staff, and asked other farmers in their farmer group. Although they had attended the IPM farmer field school, they kept on spraying insecticides but they realized that excessive insecticide use could not get rid of the planthoppers.

To prevent another outbreak, they selected a resistant variety but they soon realized that with continuous planting, they needed to keep on changing their rice variety. According to them, a resistant variety is one that requires good cultural management and is easier to manage than a susceptible one.

A BPH outbreak had occurred 10 years ago but both farmers recalled that after that outbreak, the planthoppers disappeared. This time, the outbreak was followed by grassy stunt virus and ragged stunt virus. The agriculture officials had told her that the BPH outbreak is caused by continuous rice growing which did not cut the planthoppers’ life cycle.  Wanna believes that a farmer cannot grow rice without using insecticides because other farmers also use insecticides. She expressed disbelief that planting nectar-rich flowers on the bunds can help farmers reduce their insecticide use. She explained that natural enemies can seek refuge in the flowers and vegetables on the bunds but the planthopper will go directly to the paddy and eat all their rice.

Flowers on bunds at Chainat Rice Research Center

Flowers grown on bunds at the Phitsanulok Rice Research Center

Hopperburn in Chainat province. Picture taken on August 23, 2010.

In 2009 BPH outbreaks began in July and by December Thailand had lost about a million tons of paddy. Thousands of farmers were affected and many in debt because of loans.  Hopperburn and virus disease infestations continued in early 2010. In June 2010 there were signs of BPH problems declining (Read Wantana et al). However in the next 2 months, BPH problems seem to be picking up again as farmers start planting after the drought and the release of irrigation water.

We travelled about 1500 kilometers from Bangkok to Nakhon Nayok, Phitsanulok, Chainat, Utai Thani, Phichit, Ang Thong, Ayuthaya and Suphan Buri, examining fields, visiting with farmers, policy makers, extension and research officials. Many of the factors that tend to increase vulnerability to planthopper outbreaks remain dominant, despite efforts to initiate change.

Crop intensity

In the dry season from March 2010, while many farmers had stopped planting because of water shortage, many had continued planting the next crop just 2 weeks after harvesting.  Farmers in Phichit for instance pumped underground water to continue planting. With the government’s recent release of irrigation water, more intensive planting in the next 3 months seems likely.

Rice varieties farmers are using

Last year we found that about 75% of farmers plant either Pathum Thani 1 or Chainat 1. Since these 2 varieties have been grown for more than 10 years, it is likely that planthoppers have grown adapted to them. The government started a campaign to change farmers’ varieties to more tolerant varieties, like Phitsanuluk 2 and RD 31.  However less than 10% of the farmers have adopted the new varieties, partly because of the lack of supply of new seeds but in most cases it was because Pathum Thani 1 fetched higher prices.

Insecticide use

Most farmers continue to rely on local pesticide dealers for advice and this had influenced  farmers’ use of cypermethrin, chlorpyrifos and abamectin, which are toxic to natural enemies, particularly hymenopteran parasitoids (Read: Farmers’ insecticide selection). This trend is still dominant. Although the government has recommended buprofezin, a highly planthopper specific compound and has mild effects on natural enemies, most farmers can’t get them from the local stores or are not recommended by the local dealers. In Suphan Buri we found farmers about to use buprofezin, which were free government issues. Most farmers continue to fear leaf folders and start spraying as early as 2 weeks after sowing, often as a prophylactic or on first sight of leaf folder damages. These early season sprays using resurgence causing insecticides continue to disrupt natural biological control and make fields vulnerable to BPH outbreaks (Read: Chien et al – Rice more vulnerable after early sprays).  Insecticide use in Central Thailand this year seems likely to increase. The emergency funds for insecticide purchase released last year were only available this year and loss aversion of most farmers seem higher than before.

Light trap data from Chainat province showing the 3 distinct spikes in BPH caught in 2009 and 2010. The spike in April 10 was higher than April 09 by 4 folds.

The light trap records in Chainat province in 2009 showed 3 spikes which corresponded to the 3 crop seasons in the area. The spikes in August and November were higher than that of April and there were serious hopper outbreaks  and virus infections.  This year the April spike was 4 folds larger than last year and if the fields continue to remain vulnerable there are indications that the 2010 BPH outbreaks could be 4 times more severe than 2009. At this moment, more than 50,000 ha have been recorded damaged in Suphan Buri, Ang Thong, Chainat and Singburi provinces and the Rice Department is closely monitoring its development.  Intensity and extent of damage by BPH and the related virus diseases seem likely to increase in the coming months.

Other reports on the BPH situation in Thailand are found in:

http://www.irinnews.org/Report.aspx?ReportId=90269

http://www.upi.com/Science_News/Resource-Wars/2010/08/25/Thai-rice-crop-faces-infestation/UPI-38121282739884/

http://beta.irri.org/news/bulletin/2010.34/