CHAPTER 13

Farmers perceptions and practices in weed management in Thailand

L. Meenakanit and P. Vongsaroj

Abstract

A survey of 300 rice farmers was conducted to determine their perceptions of and practices in weed management. The survey involved eight provinces of the Chao Phraya basin in the central plain and two provinces of the Pak Panang basin in the south of Thailand. The data were collected through personal interviews using a pretested questionnaire. The most important weeds present in the areas surveyed were grassy weedsnamely, Echinochloa crus-galli (L.) P. Beauv. and Leptochloa chinensis (L.) Nees, and broadleaf weeds such as Monochoria vaginalis (Burm. f.) Presl.. Chemical application was the main weed control method farmers used and 2,4-D and butachlor + propanil were the herbicides used. Most of the farmers knew that weeds are the main cause of yield reductions as well as being a harbor for other pests. A majority of the farmers expressed favorable attitudes toward weed management, such as the importance of early detection of weeds, good land preparation, synchronized planting, and application of the recommended dosage of herbicides. Among the different weed management methods, herbicide applications and mechanical methods were the options known by most farmers.

Introduction

During the past decade, rice growing in the irrigated lowlands in Thailand has gradually shifted from transplanting to wet seeding. As in other countries, the migration of farm labor into other sectors such as industry, services, construction, and overseas labor; lower investment in rice planting; the decline in real prices of rice; and higher yields of direct-seeded versus transplanted rice have been the major reasons for the shift in crop establishment method (Kanchanomai et al 1970, Panitchpat 1994). With the high rate of economic growth and industrialization, farmers face rising farm labor costs for transplanting and weeding. At the same time, real prices of rice have declined. This twin dilemma of rising labor costs and falling rice prices has been cited as an important explanation for the expansion of direct seeding in Asian countries (Jirstrom 1996, Denning et al 1983). But direct seeding has adverse effects: increased weed problems, a shift in the dominant species to grassy weeds, higher pest and disease incidence because of high planting density to prevent weeds, and difficulties in carrying out recommended cultural practices (Moody 1993). The rise in weed infestations in direct seeding results from the greater competition from weeds, which may grow along with the rice plants.

Besides competing with the rice crop for light, water, and soil nutrients, weeds smother rice because they are more vigorous (De Datta 1990). The shift in weed flora from broadleaf weeds and sedges to grassy weeds makes it difficult for farmers to differentiate weeds from rice because of their age and morphological similarity (Moody 1993).

To control weeds, most farmers rely heavily on herbicides. The availability of many types and formulations of herbicides in the market has generated problems for Thai farmers. Besides the higher input cost of herbicides, their misuse and overuse from improper selection and application are often reported. Knowing the right kind, rate, and timing of herbicide application as well as the stage of the weeds is important for effective weed control (Vongsaroj 1991, Choutummatut et al 1994). The integration of traditional weed control methods and physical methods with moderate herbicide use has been shown to have advantages over excessive dependence on herbicides. Misuse of herbicides can lead to shifts in weed populations toward perennial species and the establishment of weeds that are more difficult to control or have herbicide resistance (Labrada and Parker 1994, Heong et al 1995a). But better herbicide performance is achieved when optimum cultural practices, particularly water management, are used. Day (1972) reported that herbicides should be applied in conjunction with sound cultural management practices because the chemicals do not serve as their substitutes. The simultaneous application of a variety of practices has a synergistic effect on weeds, thus resulting in more effective control (Heong et al 1995a).

On the other hand, farmers knowledge of and attitudes toward other weed control methods seem to have been overlooked. These non-herbicide control options include proper land preparation, seed cleaning, water management, and other cultural practices to reduce weed infestation as well as propagules in the weed seed bank. As Labrada and Parker (1994) have affirmed, research must shift its focus to include farmers needs in order to encourage more effective adoption of integrated weed management.

This study aimed to identify farmers problems in weed control and to understand their perceptions, attitudes, and practices in weed management in order to design strategies to help them minimize yield losses from weed infestations. The area selected was central and south Thailand, the countrys major rice-growing areas.

Thailand

Located in Southeast Asia, Thailand is surrounded by Myanmar, Laos, Cambodia, and Malaysia. This area is under the influence of the southwest monsoon, which lasts from the middle of May until October. Annual rainfall varies from 1,000 to 2,000 mm, according to place and year. The climate, which is warm and humid, is suited to agriculture. Geographically, Thailand is divided into four main regions: the north, northeast, central plain, and the south. The central plain is regarded as the rice bowl of Thailand, whereas in the north, northeast, and south, rice is cultivated mainly for home consumption. In 1994, the total rice area was estimated to be 8.9 million ha (DOAE 1994). The main (wet) season covers 8.6 million ha.

Most of the survey provinces are flat lands situated along river basins and lakes such as the Chao Phraya River and its tributaries and Bueng Borapet Lake for Nakhon Sawan; Mae Klong and Pachee rivers for Ratcha Buri: Chao Phaya River for Chainat; Prachin Bun and Hanuman rivers for Prachin Buri; Chao Praya, Lop Buri, and Pasak rivers for Ayutthaya; Pasak and Lop Buri rivers for Lop Bun; Pasak River for Saraburi; Tachin River for Suphan Buri; Tapee, Pak Panang, Pakpoon, and Nakhon Si Thammarat rivers for Nakhon Si Thammarat; and Songkhla Lake for Phatthalung. Rainfall averages from 1,042 mm to 2,148 mm, whereas mean temperature ranges from 27.2 C to 28.8 C.

Three major rice-growing methods are practiced in Thailand: deep water, direct seeded, and transplanted. The direct-seeded method is widely practiced in the central, eastern, and western regions. In wet seeding, pre-germinated seeds are broadcast over a puddled field or in one with standing water. This method reduces labor, but it also results in heavier weed infestations. To control weeds, farmers use a high sowing rate of 125187 kg /ha. But this sowing rate produces poor tillering and a thick stand, resulting in temperature and humidity conducive to spreading disease and increasing insect pest populations.

Weed problems in rice in Thailand are similar to those of other countries in the region. The yield reduction from weed infestations ranges from 20% to 80% depending on weed species, their density, cropping season, and weed control practices. Weed infestations are usually higher in the wet season than in the dry season. The weeds generally found in most direct-seeded areas in Thailand are Echinochloa spp., Leptochloa chinensis (L.) Nees, Jussiaea linifolia Vahl, Monochoria vaginalis (Burm. f.) Presl., Sphenoclea zeylanica Gaertn., Cyperus difformis L., and C. pulcherrimus Willd. ex Kunth, among others (DOA 1989).

Official recommendations for weed management include proper land preparation and leveling, use of clean seeds, and proper selection and use of herbicides (DOAE 1995). In terms of farmers weed control practices, Meenakanit et al (1994) reported that most farmers plow two times, then harrow and puddle the soil before sowing seeds. Pre-emergence herbicides such as pretilachlor, butachlor, or oxidiazon are applied at 610 days after seeding (DAS). Herbicides, usually 2,4-D or its derivatives, are applied 1520 DAS to control broadleaf weeds that have survived even after the first application or moved in from neighboring fields. Chinawong (1993) reported that farmers still lack sufficient knowledge of herbicide selection and application in Nakhon Pathom Province and other direct-seeded areas.

Water management after herbicide application is also considered crucial for effective weed control. Flooding the field within 10 days gives better control than flooding the field 10 days after sowing (Bhandhufufalk and Hare 1985). Post-emergence herbicides will be more effective if the water level is controlled to submerge the weeds (Chinawong 1992). A seed rate of 100 kg /ha is suitable to minimize weed problems in direct-seeded rice (Kanchanomai 1981). Time of planting also affects the weed population. During the rainy season, S. zeylanica and Cyperus difformis occur more than in the dry season, whereas Echinochloa spp. and L. chinensis occur more in wet seeded rice.

Methods

Data collection

The personal interview was the main method used to collect data on farmers' perceptions, attitudes, and practices in rice weed management. The instrument, first written in English, was translated into Thai and back-translated to English to ensure that the translation reflected the intended meaning of the terms used.

Questionnaire pretesting

The translated questionnaire was subsequently pretested with rice farmers in Chai Nat to determine the clarity of the wording and translation of the technical terms used, the logical sequence of the questions, adequacy of the questionnaire instructions, and the estimated duration of the interview. Two rounds of pretesting were undertaken to try out the questionnaire using individual interviews and focus group interviews as the primary research techniques. In the first pretest, individual interviews were conducted with rice farmers to solicit their feedback to the prototype questionnaire. The second pretest involved focus group discussions to further test the revised instrument. Results of the pretest served as the basis for revisions in the questionnaire and logistical arrangements for the fieldwork. The survey was conducted by a team of Department of Agricultural Extension (DOAE) extension technicians (kaset tambon) and Plant Protection Service Unit (PPSU) technicians.

A total of 300 rice farmers who practiced direct seeding were selected from eightprovinces within the Chao Phraya, Bang Pakong, and Thachin basins in the central plain. These are Nakhon Sawan, Chainat, Lop Buri, Saraburi, Ayutthaya, Prachin Buri, Suphan Buri, and Ratcha Buri and two provinces in the Pak Panang basin of Nakhon Si Thammarat Province and

Phatthalung of the Songkhla Lake basin (Fig. 1). In each province, 30 farmers were selected randomly from two or three villages in one subdistrict.

Sampling procedure

Data processing and analysis

Survey data were encoded using a spreadsheet program and processed in a microcomputer using the Statistical Package for Social Sciences (SPSS ). In most cases, percentages were based on the total sample. Likewise, where multiple responses were obtained, the sample size was used to compute the percentages.

Results

Socio-demographic profile of farmers

The ages of rice farmers interviewed ranged from 20 to 80, with more than half belonging to the 4160 age bracket. This age distribution reflects the one found in previous studies in the Philippines (Heong et al 1995b). A large proportion of the farmers were either owner-operators (60%) or tenants (59%). Only one respondent was a hired laborer. Most (91%) had 14 years of primary schooling. Only 3% reported that they had not attended school at all and few respondents went to high school (5%) and college (1%).

Information sources

As in other farm surveys, the extension technician appears to play a key role as a source of information for rice farmers in Thailand. For farming information, the extension technician was named as a source by 59% of the farmers, followed by relatives (13%), other farmers (8%), and PPSU technicians (6%). For advice on pest management, 73% of the farmers consulted the extension technician. Only 11% reported that they approached the PPSU technician. Other sources of pest management advice cited were other farmers (4%), relatives (5%), and the radio (2%). These results are consistent with findings of earlier studies on farmers' sources of information on crop protection.

Agronomic practices

Rice varieties planted. Farmers reported planting a number of rice varieties for both the first and second cropping. For the first crop, Lueng Pratiew, a local variety was the cultivar grown by 44% of the respondents. It is taller than most hybrid varieties and commands a good market value; this explains its popularity among farmers. It was followed by Chainat (34%) and Supanburi (11%). Other local varieties grown by farmers are Kao Lueng, Puang Thong Pho Thong, Lueng Yai, Pathum 2, Lueng Tahaeng, Kao Ta-haeng, Sai Ngern, Opol, Malay, and Kao Samut. For the second crop, Chainat topped the list of varieties planted by farmers (57%), followcd by Supanburi (18%), local varieties (15%), and IR23 (6%).

Sources of rice seeds. Farmers sources of rice seeds consisted of both personal and institutional sources. Nearly half of the farmers (49%) obtained their rice seeds for planting from nearby farmers, usually their neighbors. The popularity of farmers seeds has to do with access and cost. Farmers found other farmers seeds cheaper and easier to obtain than government seeds. Almost a third (29%) procured seeds from both the seed center and DOAE seed exchange project. Some 23% used seeds from their own stock and 11% got seeds from the Department of Agriculture (DOA). Others bought seeds from the rice mill (3%), local shop (2%), and cooperative (1%).

Rice area. Most (92.3%) of the rice farmers interviewed had direct-seeded their crop. For the first crop, 39.4% of the farmers in the sample had rice farms of 3.36.4 ha, followed by 39% who managed