Vietnam Demonstration Model Project
Demonstration model in the management of Fall Armyworms in maize crops - FINAL REPORT
Background of the study
Fall armyworm (Spodoptera frugiperda) is an invasive pest that has caused significant maize losses in Vietnam since its first detection in 2019. Maize is Vietnam's second most important staple crop, essential for food security and rural livelihoods, particularly in regions such as Vinh Phuc province.
In specialised areas, maize is grown in three cropping seasons: Spring-Summer, Summer-Autumn, and Autumn-Winter. Fall Armyworm is present across all seasons, so pest pressure remains high.
​In response, demonstration trials were conducted in Vinh Phuc during the 2023 Summer–Autumn and autumn–winter seasons to evaluate effective management strategies under local farming conditions
The impacts of the Demonstration trials
In summary, demonstration trials, as deployed in this project, provide an ideal learning space for researchers, policymakers, and farmers to develop and refine practices and test solutions to ensure that they can be deployed correctly and efficiently in the field. Cost-benefit analysis is also very important in ensuring that farmers can effectively deploy IPM recommendations at scale.
Project description
This project conducted a small set of demonstration trials using proven scouting approaches combined with a focus on good agricultural practices and using lower-toxicity pesticides and biocontrol options. The aim is to build capability in monitoring and managing FAW by both researchers and farmers and to test a range of approaches to managing FAW under Vietnam conditions. Demonstration projects are used in this project as a socialization and education tool to further knowledge on FAW control and introduce new practices.
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"The goal is to enhance understanding and guide future research and behavior in the field"
General Methodology
Selection of study site
The project was divided into two separate phases, carried out in two seasons: the first phase in Summer-Autumn and the second phase in Autumn-Winter 2023 in the corn cultivation area of the Red River Delta in Vietnam. In this location, crops are regularly affected by Fall Armyworm all year round, causing significant damage to production, especially during the spring-summer season.
Figure 1. Demonstration sites in the Red River Delta in the Lowlands Agroecological Zone.
Scouting and decision to treat
​Scouting, involving the systematic assessment of FAW infestation in each plot, was undertaken every 3 days from germination to the V9 stage and every 7 days from flowering to the seed setting stage (figure 2) to determine the percent (%) infestation (%IP)
Figure 2. The Maize growth stages
The scouting protocol followed is described here:
Monitoring
​Pheromone traps were used for monitoring, and the traps were monitored as advised by expert opinion at the Plant Protection Research Institute (PRRI) Vietnam and the National University of Agriculture (VNUA) to assess the number of adults trapped. This includes using traps in test fields to understand the performance of treatments and to ensure timely intervention of solutions in the field.
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Figure 3. A) Pheromones trap in the field, B) Lure from VNUA
Training and Workshop
All farmers participating in the demonstration model and maize growers in the area participated in a training course as part of the demonstration (Fig. 4). The training course focused on helping farmers distinguish FAW from other insect pests and to better understand FAW behaviors and characteristics. The growers were provided training on Integrated Pest Management (IPM) solutions. 62 maize growers participated in the training course.
Figure 4. Training course on IPM solution for the local farmers
Figure 5. International workshop on PMP+ in Hanoi, Vietnam
The Plant Protection Research Institute, Plant Protection Department, and the ASEAN FAW Action Plan organized an international workshop in Hanoi from 3 to 6 December 2023 (Fig. 5). Seventeen participants from nine South and Southeast Asian countries, along with local agricultural experts and industry representatives, attended.
Key findings
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Maize is always under very high pressure from FAW in the study locations. Without the early application of a control measure, maize is typically heavily damaged as early as the emergence stage (V3). The percentage of infested plants (% IP) increases up to 100% during the V5- V9 stages, leading to a potential yield reduction of up to 50% compared to effectively managed fields.
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Moth counts were extremely high in the summer season but decreased sharply in the autumn season. However, even the lower counts were still considered high, and one can expect FAW to be a permanent serious pest that farmers must proactively manage in this region. At these high levels of FAW population, a package of IPM solutions will be needed to manage FAW effectively and maintain good yields.
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The results clearly showed the importance of good agricultural practices. Proper field preparation and plant health management make a big difference in yield and income. Farmers were provided with some training as part of this project, and they responded positively to the training and were curious about new solutions. Follow-up training is important.
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Soil pH test results show that most soils have a pH ranging from 4 to < 6, which is considered low
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Farmers generally did not scout often enough, and they missed opportunities to effectively control FAW early (if at all).
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Further investigation of the plants affected by FAW during the vegetative stage across the 12 treatments in Phase 1 indicated that larvae began to appear 7 days after planting. Subsequently, the %IP increased rapidly from stages V3-V5. One recommendation might be to increase scouting intensity from the V3-V5 stage to ensure better timing of any control measure.
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There is potential to make large pesticide use production, even reducing pesticide use by 50%, with better timing of pesticide applications alone. Combined with good agricultural practices and biocontrol solutions, there is a significant opportunity to drive more sustainable and effective management of FAW. More farmer training beyond this project is particularly important in scouting and understanding best practices on when to apply rescue treatments.
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The results of this demonstration project showed that an early biopesticide spray, timed correctly and at an action threshold of 20% infestation, was very effective.
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GM maize showed good tolerance to FAW in the experiments, especially the DK6919S variety, which recorded minimal damaged plants. In contrast, the NK7328 Bt/Gt variety had the highest %IP of approximately 33% at the V7-V9 stage but performed well under conditions without pesticides.
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The results of the trials showed that the farmers could realize higher yields of around 20-30% compared with local farmers' practices, leading to an increase in income of around US500-800 per ha.
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Some biocontrol options were not particularly effective (e.g., earwigs), while others did show promise (e.g., nematodes), but it is unclear if these are scaleable options. Nematode solutions and Fawligen (NPV) were less convincing in phase 1 when the FAW population was extremely high, but they showed good results in phase 2 when population levels were lower, and temperatures were cooler.
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More trials are recommended to investigate more efficient applications and scale-up of both biocontrol approaches.
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The new pheromone-based solutions for FAW management combined with biopesticides and as part of an IPM package showed much promise. They will likely be a good fit for an area-wide FAW control program, especially as maize is grown year-round and the pest is endemic. These solutions need further testing in the field in Vietnam to refine their use and effectiveness. In addition, the registration process for these solutions needs further development to ensure such approaches can be used and scaled in Vietnam.
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An insecticide seed treatment before planting did not appear as effective as expected in the single-treatment trials. However, it showed more substantial results in the Combined Treatment Package of Phase One. However, neonicotinoid pesticides in seed treatments pose risks to animals, especially pollinators. Developing lower toxicity or alternative seed treatments could be beneficial due to early pest pressure on maize in this location where FAW population levels are high across all maize growing seasons.