An assessment of the benefits of training Thai farmers in the safe use of crop protection products such as paraquat has shown that good product stewardship clearly has positive effects on the care farmers take in storage, handling and spraying.
Training Thai farmers in safe practices
The survey conducted by Kasetsart University also revealed the rich diversity of crops grown in western Thailand.
The training was conducted as part of a wider project, ‘The Safe and Sustainable Production of Horticultural Crops’, aimed at improving the quality of vegetable production systems in Thailand according to internationally recognised standards of Good Agricultural Practice. Export markets are important to the country and its farmers, so meeting stringent requirements for quality and sustainability are essential.
Successful training
Two hundred farmers participated in the training. They were shown how to store, mix and apply crop protection products safely. The post-training survey indicated that participants are now much more likely to store products in dedicated and secure chemical stores, and to use appropriate personal protective equipment (PPE), such as gloves, aprons and face shields when pouring and mixing with water in the sprayer. In the fields when spraying, again they are now much more likely to use the right PPE.
Farming in western Thailand
Asparagus growing in Thailand
The average size farm size of participants was about 2.4 rai which is less than half a hectare. Asparagus was the most popular crop, being grown by almost all farmers. In recent years the value of the asparagus export market, especially to Japan and Taiwan, has increased at an annual rate of 60%1. Agronomically, asparagus is interesting because it is recognised as the most salt tolerant vegetable crop2.
In the surrounding fields a huge number of crops were recorded in the survey. Sugar cane and corn were most widely grown. The next largest group comprised rice, bananas, cassava, taro, aubergines, shallots, Chinese parsley and chilli peppers. Smaller areas were down to many other vegetables including okra, cabbages, tomatoes and several types of beans; fruit including mango, guava, papaya and dragon fruit; and exotic herbs such as bergamot and roselle.
Paraquat’s versatility
Paraquat is a versatile product for an enormous number of crops because it can be used to control weeds growing between crop rows. If necessary, a simple shield can be used around spray nozzles, but even if spray droplets land on crop leaves there is no effect on yield or quality because paraquat is a contact-only herbicide. Unlike glyphosate it does not move systemically within plants, so cannot reach developing grain or fruit. Immediately on contact with soil paraquat is deactivated. It is bound extremely tightly to soil particles, so cannot leach. Therefore, it does not affect the roots of growing crops and any following crop can be planted without any delay. Similarly, paraquat allows a new generation of weeds to grow, which helps to anchor the soil on sloping fields prone to erosion. Young weeds can then be quickly and easily removed by a further application of paraquat before they are large enough to compete with the crop.
Although termed a non-selective herbicide, because of its contact-only action and inactivation in soil, it can be used before planting and in between crop rows with complete safety to whatever crop. Selective herbicides are generally for use on only one crop or on a few closely related ones. Thai farmers rely on paraquat to control weeds in their diverse cropping systems.
References
- World Bank (2005). Shrimp, fresh asparagus and frozen green soybeans in Thailand. Agriculture and Rural Development. Discussion Paper 16.
- Shannon, M C and Grieve, C M (1999). Tolerance of vegetable crops to salinity. Scientia Horticulturae, 78, 5-38