Evaluating the economic impact of pathogen tested and conventional practice sweet potato production in the highlands of PNG

Richard Culas, Coleman Pombre, Alex Agiwa

Research output: Other contribution to conferenceAbstractpeer-review



Assessing the socio-economic impact of novel technologies in the control of pests and diseases of sweet potato production in Papua New Guinea (PNG).


Sweet potato (Ipomoea batatas) is a major staple food crop in Papua New Guinea (PNG). Around 90% of PNG’s population consists of semi-subsistence smallholder farmers for whom sweet potato is a major food crop. It is grown extensively in the high-altitude highlands as a subsistence food crop by smallholder farmers and is developing into commercial production for cash income. The national demand for sweet potato is high and increasing and the income elasticity of sweet potato is positive. Sweet potato production is profitable and the profit from its production can be increased (doubled) when improved technologies are used by famers. Thus, PNG has a comparative advantage in sweet potato production. However, pests and diseases attack especially roots and foliar attack by a wide range of pests and diseases remains a major challenge. Majority of the PNG farmers do not practice an active pest and disease management, which has a significant impact on the yield and farmers’ income. Few farmers have opted to use cultural practices to manage the pests and diseases, though these methods are ineffective and expensive. Therefore, an alternative intervention technology (innovative method) through introducing pathogen tested (PT) seeds is required to produce pest and disease damage free quality tubers. Countries which use pathogen tested planting materials, for instance, Australia has reported producing more than 30-35t/ha tubers, while conventional practice (CP) farmers in PNG reported 15t/ha in the highlands and 13t/ha in the coastal areas. There is a potential to improve yield and income of smallholder sweet potato farmers in PNG by adopting to PT.


The economic impact of adopting to new method (PT) to control pests and diseases can result increase in yield and reduction of costs. This can therefore increase net farm income (as illustrated by a profit maximization model). A Farmer Participatory Research (FPR) approach field trail was conducted in the central high-altitude provinces in PNG. Four farmers from three different provinces participated in the FPR for testing and comparing economic impact of PT with CP sweet potato planting materials. Each farmer planted both PT and CP vines on a 12m x 16m plots. The income from tubers produced, yield and their costs of production were calculated and compared by benefit cost ratios (BCR). The farmers’ perceptions on adopting to PT sweet potato planting materials (as compared to the CP methods) were surveyed using structured questioners administered to the farmers. The farmers’ responses were scored using perception rating scale from, 0-2, representing 0 being not effective, 1 for less effective and 2 being effective. Summary of these scores are given in percentage out of the four farmers from each province (zone).

Results and discussion:

The average marketable yield doubled and was highly significant (p < 0.01) for PT compared to CP. The increase in yield also resulted in highly significant increase in income from PT. However, the costs for labour, transport and marketing were significantly high (p <0.05) for PT than CP. The transport and marketing cost is high for PT to reach better market destinations due to the good quality of tubers. Despite that the overall net return from PT was still higher compared to CP. The BCR for PT showed more than 2 indicating a positive effect on the benefit for all three zones and also the BCR doubled (compared to the CP) for two of the three zones.

All the participating farmers in all three zones responded 100% for willingness to uptake the PT sweet potato production systems after seeing the results. They had indicated that the PT planting material eliminated the pests and diseases damage on tubers, which has increased the marketable quality of the tubers and subsequent increase in income. Hence the adoption of PT method can be promoted in PNG for improving the rural farmers’ income and livelihood from PT sweet potato production. Sweet potato is also a strategical crop in PNG for its food security objectives and that promoting the use of PT method can contribute towards these objectives.


Sweet potato, pests and diseases, novel technologies, economic impact, PNG
Original languageEnglish
Number of pages3
Publication statusPublished - 09 Feb 2021
Event65th AARES Annual Conference - University of Sydney, Sydney NSW, Australia
Duration: 09 Feb 202112 Feb 2021


Conference65th AARES Annual Conference
CitySydney NSW
Internet address


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