CHAPTER 15Pest management perceptions and practices of rice farmers

in Long An Province, VietnamVo Mai, N.H. Huan, K.L. Heong, M.M. Escalada, and A.A. Lazaro

Abstract

A survey of 633 rice farmers conducted in August 1994 in two districts, Tan Tru and Tan Thanh, in Long An Province, showed that brown planthoppers, sheath blight, and leaf folders were farmers’ most important rice pests. Farmers often sprayed pesticides to control them. Particularly for leaf-feeding insects, insecticide sprays were applied during the first month after seeding. These insects were perceived to be very damaging because they can cause heavy yield losses in rice. Early season insecticide sprays for their control were thus believed to be necessary. Organophosphates, such as methamidophos, monocrotophos, and methyl parathion, were the most popular insecticides used to control leaf feeders. These insecticide applications may have been unnecessary because rice plants have the ability to compensate for leaf defoliation. Early applications of broad-spectrum insecticides may cause ecological disruptions that can favor brown planthopper development. Farmer participatory research, strategic extension campaigns, and pest management training to help farmers realize that these early insecticide sprays are not beneficial should be increased.

Introduction

Rice intensification programs in the 1970s introduced insecticides as a necessary input for high yields. Prophylactic insecticide applications were “packaged” into production programs and farmers were encouraged to use them at regular intervals. Government subsidies and agricultural loan schemes together with strong marketing and advertising by the chemical industry (Escalada and Heong 1993) further supported insecticide use (Conway and Pretty 1991).

In Vietnam, rice production between 1970 and 1980 remained low at around 11 million t /year. With the introduction of policies to improve contractual arrangements, referred to as Contract 100, in 1981, rice production increased by about 30% (Cuc 1995). In 1989, Resolution N10 was introduced and rice production increased further, reaching 22 million t /year. This marked the beginning of decollectivization, which encouraged farmers to invest in inputs and labor (Pingali and Xuan 1992). Thus, the use of chemical inputs such as fertilizers and pesticides increased. Stimulated by aggressive advertising and marketing, insecticide use in 1992 was around 5 sprays /season (Heong et al 1994) and about 80% of the farmers applied their first sprays within the first 40 days after sowing.

This paper presents the results of a baseline survey conducted in August 1994 to document farmers’ pest management perceptions and practices in two districts, Tan Tru and Tan Thanh, in Long An Province.

Long An Province

Long An is a province of the Mekong Delta in the southern part of Vietnam. The province extends from 105° 30’ to 106° 45’ east, and from 10° 08’ 30” to 11° 02’ 30” north (Fig. 1). The total area is 4,355 km2 and agriculture plays a dominant role in the economy. Rice is the principal crop; it is cultivated on 363,000 ha, 80% of which are irrigated. The total farmer household population is 210,000, 85% of which is engaged in rice farming. Long An produces

1.16 million t /year of rice. Besides rice, watermelon, groundnuts, and cash crops are also cultivated. In most areas, farmers grow two crops a year; in some areas, three rice crops /year are grown. Modern high yielding rice varieties are commonly planted in more than 80% of the rice areas. In some districts, the aromatic traditional varieties are popular, particularly during the wet season.

Methods

In August 1994, a farmer survey was conducted in Long An Province to determine rice farmers’ pest management practices and perceptions. Before being used, a structured questionnaire was pretested by local technicians through field interviews with 20 farmers. The pretest was intended to solicit farmers’ responses to the survey questions, which were used to further refine the questions. For the survey, 633 rice farmers were selected randomly from 16 villages in two districts, Tan Tru and Tan Thanh, where rice was the main crop. These farmers were interviewed by the agricultural technicians trained to use the pretested survey questionnaire. The field data were immediately translated, coded, and entered in a spreadsheet program. Frequency distributions and cross-tabulations were generated using the frequency procedure in the Statistical Analysis System (SAS) package (SAS 1985). Means were compared using the t-test procedure. In addition, the authors carried out several follow-up focus group interviews to obtain further information using probing techniques.

Results

Profile of farmers

More than half (55%) of the farmer respondents interviewed in Tan Tru and Tan Thanh were 31–50 years old. Only a small percentage (6%) did not have any schooling, whereas 81% had from 1 to 9 years of education (Table 1).

Modern high-yielding rice varieties such as IR9729, IRS0404, and IR49517 were the most common cultivars planted by the farmers during the summer-autumn season of 1994. Farmers either kept their own seeds (34%) or exchanged them with their neighbors (46%). More than 80% of the farmers in the survey followed a rice-rice cropping pattern and 97% direct-seeded their rice. Almost 90% of the farmers cultivated rice lands of less than 2 ha and 97% said they owned the land they managed.

Pest management practicesFarmers in Long An Province used mainly pesticides to manage pest problems. Nearly all farmers (99%) used pesticides during the summer-autumn 1994 season. The 633 farmers interviewed reported using a total of 3,033 sprays. Of these, about 70% were insecticides, 28% fungicides, and 2% herbicides. Most farmers (80%) applied pesticides 2–5 times. About 84% applied their first insecticide treatment within the first month after crop establishment (Fig. 2); their main targets during this period were thrips, leaf folders, brown planthoppers (BPH), caseworms, and stem borers. These were also common targets at the booting stage. Sheath blight and yellow leaf disease were targets from the booting to soft dough stage, and rice bugs at the milking stage.

Pesticide use

Organophosphates were usually the most popular insecticides used for insect pest control in rice. Methamidophos was the predominant compound used to control leaf folders, caseworms, and stem borers (Table 2). It was also used on thrips and rice bugs, although most farmers used methyl parathion for these pests. For brown planthoppers, fenobucarb was the most common pesticide used, followed by buprofezin and methamidophos; for sheath blight, farmers used the fungicide hexaconazole.

About 34% of the total pesticide sprays were compounds in WHO category I and 30% were in category II. The rest were WHO categories III (1%), V (30%), and unclassified (5%).During the 1994 season, 2,123 insecticide sprays were applied by the farmers we interviewed. Most sprays targeted one pest, although some targeted two or three (Table 2). Of the 2,564 intended targets, 33% were leaf folders, 28% BPH, 14% thrips, 10% stem borers, 7% caseworms, 4% rice bugs, and the rest other insects. The lepidopteran leaf feeders constituted 43% of the intended spray targets.

Farmers in the two districts used 849 fungicide sprays and, of the 932 spray targets mentioned, 71% were sheath blight, 26% were yellow leaf disease, and 2% were blast (Table 3). Although more is known about sheath blight and blast, the causal agent of yellow leaf disease is still unknown.

Farmers ranked the brown planthopper (27%) as the most important pest problem, followed by sheath blight (26%), leaf folders (16%), and yellow leaf disease [tungro] (10%). Most farmers applied pesticides for these pests (Table 4). Only 0.5% of the farmers mentioned that they used other control measures such as water management, baiting, and handpicking.

Pest management knowledge and perceptions

More than 80% of the farmers interviewed believed that pesticides would kill 75– 100% of the pests in their rice fields, but about 73% did not know that killing natural enemies can induce population buildups of other pests such as the brown planthopper. Leaf-feeding insects were the most frequently sprayed; the most common ones that farmers mentioned were leaf folders (84%), caseworms (56%), armyworms (46%), and thrips (23%). Most farmers perceived that leaf-feeding insects would cause severe damage and yield losses to the rice crop (Fig. 3). They also believed that it was necessary to spray early to control these pests. We compared rice yields reported by farmers who sprayed early (during the first month of the summer-autumn crop of 1994) and those who sprayed later (after the first month) using the Student t-test and found them to be not significantly different (P = 0.3). The mean yields were 3.4 t /ha (n = 578, SD = 1.09) and 3.8 t /ha (n = 49, SD = 1.21), respectively.

Discussion

Farmers’ pest management practices in Long An did not appear to be different from those of farmers interviewed in the Mekong Delta in May 1992 (Heong et al 1994, Vo Mai et al 1993). The number of sprays /farmer per season dropped from 7 in 1992 to 5 in 1994. Proportionally more fungicides were used in 1994, increasing from 3% to 28%. Insecticide sprays dropped from 6 to 4 /farmer per season. But insecticide use patterns were rather similar (Table 5). Organophosphates and carbamates were the main insecticides used. Highly hazardous WHO category I compounds constituted 48% of the insecticide sprays in 1994, versus 37% in 1992. The main insecticides used were methyl parathion (12%), methamidophos (29%), and monocrotophos (7%). Farmers’ target insect pests—mainly leaf-feeding insects and BPH—had

remained unchanged (Table 6). The main insecticides used to control leaf-feeding insects were still methamidophos and methyl parathion, whereas carbamates were used to control BPH. In addition, farmers’ first insecticide applications were mainly in the first 4 weeks after crop establishment, similar to that found in 1992.

From May 1992 to August 1994, the Ministry of Agriculture, together with FAO, started implementing farmer field schools (FFS) in Vietnam. This farmer training program has adopted the same model used in Indonesia (Matteson et al 1994). Farmers, after the FFS training, were found to reduce their insecticide inputs significantly (Matteson et al 1994). In Tan Tru District, the first FFS was conducted in the wet season 1993 and, in August 1994, 11 FFS were conducted and 297 farmers trained. In Tan Thanh District, the FFS started in late 1994 and, in August 1994, 6 FFS were implemented and 170 farmers trained. The total population of rice farmers in these two districts was about 20,000 and fewer than 3% of the farmers had undergone training at the time of the survey. Therefore, this could not have accounted for the reduction in insecticide use between 1992 and 1994. Moreover, farmers’ spray patterns had not changed; farmers continued to apply insecticides early in the crop season to control leaf-feeding insects.

Lepidopteran larvae, particularly rice leaf folders, continue to be farmers’ main pest targets. Most farmers still perceive that leaf-feeding insects cause severe damage and yield losses, and that early season spraying is necessary. But field infestations with as much as 67% damaged leaves did not cause any yield loss (Miyashita 1985). Using computer simulations, Fabellar et al (1994) found that leaf consumption by 20 larvae /hill was insufficient to significantly reduce crop yield. The average larval densities in rice crops, on the other hand, are far below these densities. In the Philippines, populations were under 1 /hill (Guo 1990) and, in Japan, the average was below 2 (Wada and Shimazu 1978). Populations rarely reached 5 larvae /hill.

Practically no evidence shows that early season sprays against rice leaffolders are economically justifiable. Indeed, when farmers evaluated early season spraying, yields of their plots with and without early insecticide sprays were not significantly different (Heong et al 1995, Heong and Escalada 1998). Thus, the high proportion of insecticides used by Long An farmers was still based on perceived rather than real needs. The main insecticides farmers used had broad-spectrum mortality effects, which have been shown to have detrimental effects on ecological balance (Cohen et al 1994, Way and Heong 1994). These insecticides could cause secondary

pest problems, such as brown planthopper (Kenmore et al 1984, Heinrichs and Mochida 1984, Schoenly et al 1994). In addition, the insecticides in WHO category I are hazardous to human health (Rola and Pingali 1993).

Among diseases, farmers perceived sheath blight and yellow leaf disease as the most important. Fungicides were used mainly when disease symptoms were visible. For sheath blight, fungicides might have worked, because the chemicals used— hexaconazole and validamycin—can control the disease. For effective control, sprays had to be timed appropriately. The survey, however, did not solicit fungicide timing information. The causal factor of yellow leaf disease is still controversial. Farmers had perceived the symptom to be a disease and had adopted the use of fungicides. But whether the fungicide sprays used had prevented yield loss is uncertain. Clearly, scientists need to better understand farmers’ knowledge, attitudes, and practices in managing diseases in order to improve decision making. As pointed out by Bentley (1992), because diseases are important but difficult to observe, scientists have opportunities to help expand existing folk taxonomies, enhance farmer observations, and challenge existing beliefs.

The insect pest management practices of Long An farmers were found to be far from satisfactory because unnecessary insecticide use was widespread. An obvious need is farmer training. At the time of the survey, only 6% of the farmers interviewed said they had attended training. If higher proportions of farmers were trained, unnecessary spraying could decrease. Farmer training through the FFS approach has been found to be effective (Matteson et al 1994). In Indonesia, where this training method was introduced in 1989, 200,000 farmers (or 1.3%) were trained in 4 yr (van de Fliert et al 1995). If FFS training were to cover the estimated 15 million farmers in Indonesia and the current training rate were maintained, it would take 18 yr to train all 15 million.

In August 1994, 83 FFS began in Long An and 2,000 farmers were trained. Bythe end of 1996, 8,000 (or 4% of the province’s estimated 200,000 farmer families) were expected to be trained. To reach the remaining 96%, a drastic increase in the number of FFS being implemented and financing would be needed. Meanwhile, other options with a wider and faster reach need to be evaluated. Unnecessary insecticide applications brought about primarily by misperceptions will continue to plague farmers unless alternative information that can change their perceptions reaches them. The use of strategic extension campaigns effectively influenced farmers’ rat control and weed control practices in Malaysia (Adhikarya 1994, Matteson et al 1994).

Although an initial 5% increase in herbicide use was noted immediately after the weed management campaign in 1989 (Matteson et al 1994), herbicide use dropped by 33% in 1993 (Adhikarya 1994). In addition, farmers’ land leveling practices contributed to better weed management. The cost-benefit ratio of the integrated weed management campaign was estimated at 1:50. The use of media perhaps needs to be re-examined.

These methods of communication use systems readily available to farmers and can disseminate information rapidly. The problem at hand seems to be more related to misperceptions and attitudes of farmers. Research on the content, format, and mechanisms to communicate different information on pest management in various sociocultural and political contexts may be useful.

Responses to media across cultures may vary because of differences in visual literacy. For instance, in Honduras, farmers can be distracted and sometimes offended by comic-book pamphlets (Goodell et al 1990). Farmers preferred pamphlets with naturalistic line drawings and

clear technical prose (Bentley and Andrews 1991). Discovering the critical misperceptions and attitudes and identifying mechanisms for effecting a rapid change in pest management practices are still important and immediate challenges.

References

Adhikarya R. 1994. Strategic extension campaign: a participatory-oriented method of agricultural extension. Rome, Italy: FAO.

Bentley JW. 1992. Alternatives to pesticides in Central America: applied studies of local knowledge. Culture and Agriculture 14:10-13.

Bentley JW, Andrews K. 1991. Pests, peasants and publications: anthropological and entomological views of an integrated pest management program for small-scale Honduran farmers. Human Organization 50:113-124.

CIRAD (International Cooperation Centre in Agronomic Research for Development). 1991. Regional agro-pesticide index, Volume 1: Asia. 3rd ed. Paris (France): CIRAD.

Cohen JE, Schoenly K, Heong KL, Justo H, Arida G, Barrion AT, Litsinger JA. 1994. A food web approach to evaluating the effect of insecticide spraying on insect pest population dynamics in a Philippine irrigated rice ecosystem. Journal of Applied Ecology 31:747-763.

Conway GR, Pretty JN. 1991. Unwelcome harvest: agriculture and pollution. London: Earthscan Publications.

Cue NS. 1995. Agriculture of Vietnam 1945-1990s. Hanoi, Vietnam: Statistical Publishing House. 386 p.

Escalada MM, Heong JSL. 1993. Communication and implementation of change in crop protection. In: Crop protection and sustainable agriculture. CIBA Foundation Symposium 177. Chichester: J. Wiley & Sons. p. 191-207.

Fabellar LT, Fabellar N, Heong KL. 1994. Simulating rice leaffolder feeding effects on yield using MACROS. International Rice Research Newsletter 19(2):7-8.

Goodell GE, Andrews KL, Lopez J. 1990. The contribution of agronomo-anthropologist to on farm research and extension in integrated pest management. Agricultural Systems 33:321-340.

Guo Y. 1990. Larval parasitization of rice leaffolders (Lepidoptera: Pyralidae) under field and laboratory conditions. PhD thesis. University of the Philippines, Los Baños.

Heinrichs EA, Mochida, O. 1984. From secondary to major pest status: the case of insecticide induced rice brown planthopper Nilaparvata lugens resurgence. Protection Ecology 7:201- 218.

Heong KL, Escalada MM. 1998. Changing farmers’ pest management practices through farmer experimentation. International Journal of Pest Management 44 (4): 191-197.

Heong KL, Cuc NTT, Binh N, Chien HV, Fujisaka S, Bottrell DG. 1995. Reducing early season insecticide applications through farmers’ experiments in Vietnam. In: Denning GL, Xuan VT (editors). Vietnam and IRRI: a partnership in rice research. Manila (Philippines): International

Rice Research Institute, and Hanoi, Vietnam: Ministry of Agriculture and Food Industry. p. 217-222.

Heong KL, Escalada MM, Mai V. 1994. An analysis of insecticide use on rice: case studies in the Philippines and Vietnam. International Journal of Pest Management 40(2):173-178.

Kenmore PE, Cariño FO, Perez CA, Dyck VA, Gutierrez AP. 1984. Population regulation of the rice brown planthopper Nilaparvata lugens (Stål) within rice fields in the Philippines. Journal of Plant Protection in the Tropics 1:19-38.

Mai V, Cuc NTT, Hung NQ, Chau LM, Chien HV, Escalada MM, Heong KL. 1993. Farmers’ perceptions of rice pest problems and management tactics used in Vietnam. International Rice Research Newsletter 18(2):31.

Matteson PC, Gallagher KD, Kenmore, PE. 1994. Extension of integrated pest management for planthoppers in Asian irrigated rice: empowering the user. In: Denno R, Perfect TJ, editors. Planthoppers: their ecology and management. London: Chapman and Hall. p. 656- 685.

Miyashita T. 1985. Estimation of the economic injury level in the rice leaffolder, Cnaphalocrocis medinalis (Guenée) (Lepidoptera: Pyralidae). I. Relation between yield loss and injury of rice leaves at heading or in the grain filling period. Japan Journal of Applied Entomology and Zoology 29:73-76.

Pingali PL, Xuan VT. 1992. Vietnam: decollectivization and rice productivity growth. Econ. Devel. Cult. Change 40:697-718.

Rola A, Pingali PL. 1993. Pesticides, rice productivity and farmers’ health: an economic assessment. Washington D.C.: World Resources Institute, and Manila, Philippines: International Rice Research Institute.

Schoenly KG, Cohen JE, Heong KL, Arida GS, Bamon AT, Litsinger JA. 1994. Quantifying the impact of insecticides on food web structure of rice-arthropod populations in a Philippine farmer’s irrigated field: a case study. In: Polis GA. Wisemiller K, editors. Food webs: integration of patterns and dynamics. London: Chapman and Hall. p. 343-351.

SAS (Statistical Analysis System). 1985. SAS user’s guide statistics. Version 5 edition. Cary, North Carolina, USA: SAS Institute, Inc.

van de Fliert E, Pontius J, Roling N. 1995. Searching for strategies to replicate a successful extension approach: training of IPM trainees in Indonesia. European Journal of Agricultural Education and Extension 1:41- 63.

Wada T, Shimazu M. 1978. Seasonal population trends of the rice leaf roller, Cnaphalocrocis medinalis Guenée (Lepidoptera: Pyralidae). Applied Entomology and Zoology 17:278-281.

Way MJ, Heong KL. 1994. The role of biodiversity in the dynamics and management of insect pests of tropical irrigated rice—a review. Bulletin of Entomological Research 84:567-587.

Notes

Authors’ addresses: Vo Mai and N.H. Huan. Department of Plant Protection, Ministry of Agriculture and Rural Development, S.R. Vietnam; K.L. Heong and A.A. Lazaro. Entomology and Plant Pathology Division, International Rice Research Institute, P.O. Box 933, 1099 Manila, Philippines; M.M. Escalada, Department of Development Communication, Visayas State College of Agriculture, Baybay, Leyte, Philippines.

Acknowledgments: The authors wish to express their appreciation to the Swiss Agency for Development and Cooperation, which supported this research through the Rice Integrated Pest Management Network, coordinated by the International Rice Research Institute in Los Baños, Philippines. Many people contributed to this research. In particular, the authors are grateful to Madam Sui, the Vice Chairperson of the People's Committee of Long An Province, and Madam Ngoc and her staff who helped implement the survey.

Citation: Vo Mai, NH Huan, KL Heong, MM Escalada, AA Lazaro. 1997. Pest management perceptions and practices of rice farmers in Long An Province, Vietnam. p. 213-225. In: Heong KL, Escalada MM (editors). 1997. Pest management of rice farmers in Asia. Manila, Philippines: International Rice Research Institute, 245 p.