Abstract
After the Doi moi policy reform of Vietnam in 1986, the government has increasingly emphasized diversification of agricultural production into high value crops. Over the period 1985-1995, fruit production in the Mekong Delta increased from 92,100 to 175,700 ha mainly due to better land tenure security. However, the potential of the fruit industry is not yet fully exploited. Besides pest and disease problems, fruit farmers lack an efficient marketing, credit and transport system. The agro-business has quickly responded to the government's policy reform. Pesticides and chemical fertilizers have become increasingly important at the expense of traditional practices of biological control. This study has tried to assess the agronomic, economic and social conditions influencing farmers' knowledge, perceptions and practices in pest management. Case studies are presented for mango, citrus and sapodilla.
The ease of observation is an important aspect contributing to farmers' knowledge and perception of pests. As for rice, fruit farmers readily targeted pests such as leaf-feeding insects, which cause conspicuous damage symptoms. Cultivation practices may interfere with pest monitoring. Because mango trees are never shaped by pruning and trimming, trees often grow 8 m high or more. Therefore, damage of the mango seed borer Deanolis albizonalis (Lepidoptera: Pyralidae) was often wrongly attributed to the fruit fly Bactrocera dorsalis (Diptera: Tephritidae), a situation which has recently improved due to extension and media activities. Citrus farmers have learnt about the existence of difficult-to-observe pests, such as the citrus red mite Panonychus citri (Acarina: Tetranychidae) and thrips (Thysanoptera: Thrips sp. and Scirtothrips sp.) through pesticide advertising campaigns by the Extension Service or through farmer-to-farmer promotion of certain acaricide products.
Those fruit farmers knowing about natural enemies have acquired this knowledge only by observing their own orchard and refrained from applying pesticides on a calendar basis, which is commonly practiced by most other fruit farmers. However, because orchards are relatively closed habitats and competition between farmers is high, farmer-to-farmer information exchange about advanced farming techniques, including the manipulation of predatory ants, is quite uncommon. In 1998, about 75% of the sweet orange ( C sinensis ) and 25% of the Tieu mandarin ( C. reticulata ) orchards had large weaver ant Oecophylla smaragdina (Hymenoptera: Formicidae) populations, due to a lower pesticide pressure in the first crop. In citrus orchards with O. smaragdina fewer pesticide sprays and chemical fertilizers were used without affecting either the yield or the farmers' income.
Farmers relying on pesticide advice from the media advertisements sprayed insecticides more frequently and applied more different products, whereas the extension has stimulated the use of acaricides and increased the number of both insecticide and fungicide sprays. The traditional practice of biological control with O. smaragdina might be endangered with growing media influence and when extension activities remain confined to chemical pest control. Citrus farmers with O. smaragdina or sapodilla farmers with the black ant Dolichoderus thoracicus (Hymenoptera: Formicidae) in their orchard all used fewer highly toxic WHO Category I insecticides than those without ants. The majority (61%) of sapodilla farmers considered D thoracicus as beneficial in decreasing damage by the fruit borer Alophia sp. (Lepidoptera: Pyralidae). Promoting wider use of D. thoracicus may be difficult, because 30% of the farmers said that this ant increases populations of the mealybug Planococcus lilacinus (Homoptera: Pseudococcidae). In six on-farm experiments, the mealybug P. lilacinus was not affected by D. thoracicus , but Alophia sp. populations were significantly smaller in ant-abundant trees.
By evaluating fruit farmers' knowledge, perceptions and pest management practices with a systems approach, this study has identified weaknesses and strengths for the development of IPM fruit programmes in Vietnam, which could also provide information to improve fruit pest management in other tropical countries.
Key words:Deanolis albizonalis , Alophia sp., Planococcus lilacinus , Panonychuscitri , Dolichoderusthoracicus , Oecophyllasmaragdina , Vietnam, natural enemies, pesticides, agricultural knowledge systems
Original language | English |
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Qualification | Doctor of Philosophy |
Awarding Institution |
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Supervisors/Advisors |
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Award date | 4 Sept 2000 |
Place of Publication | S.l. |
Print ISBNs | 9789058082671 |
DOIs | |
Publication status | Published - 4 Sept 2000 |
Keywords
- fruit trees
- mangoes
- sapodillas
- citrus
- mangifera indica
- manilkara zapota
- insect pests
- control methods
- biological control
- farm management
- farmers
- perception
- knowledge