By Dr Rebecca Sarku

1. Introduction

Tomato farmers in southern Ghana face significant losses due to Tomato Spotted Wilt Virus (TSWV), primarily spread by the western flower thrips (Frankliniella occidentalis). This virus affects tomato yield, threatening food security and farmer incomes. Research indicates that early spring weather conditions, particularly high temperatures and low rainfall, influence the spread of TSWV. Understanding these conditions and implementing targeted adaptation strategies can mitigate its impact.

2. Method

Field Surveys & Focus Groups: Conducted interviews and discussions with farmers in the Ada East and West Districts to document TSWV occurrence for (2020-2023)
Meteorological Data Analysis: Examined historical temperature and rainfall trends (1960-2023) using ERA 5 Copernicus Climate Change Service.
Statistical Analysis: Used multinomial logistic regression to identify weather conditions influencing TSWV outbreaks.

3. Key Finding

Temperature-TSWV Correlation: High temperatures (29°C-32°C) between January and March promote thrips activity, leading to increased TSWV cases.
Rainfall Suppresses Thrips: Increased rainfall reduces thrips populations, limiting TSWV transmission. Low rainfall in early spring correlates with high virus spread.
Nursery Infection Risk: The virus likely originates in nurseries before spreading to farms. Early detection is crucial for control.
Peak Infestation Period: Farmers report highest TSWV occurrences from March to July and during minor planting seasons (September-November).
Farmers primarily rely on chemical pesticides, which have proven ineffective once plants are infected.

4. Adaptation Strategies for Farmers

Early Detection & Prevention: Inspect seedlings for thrips and virus symptoms before transplanting.
Integrated Pest Management: Use resistant varieties, sticky traps, and organic pesticides.
Irrigation Planning: Maintain soil moisture to reduce thrips infestations during dry seasons.
Cultural Practices: Rotate crops, remove infected plants, and avoid planting tomatoes near thrips host crops.

5. Recommendation for Agricultural Extension Services & Policymakers

Climate-Based Pest Forecasting: Develop TSWV risk indices incorporating temperature and rainfall data.
Training & Awareness: Educate farmers on thrips control strategies and nursery management.
Weather Information Services: Provide localized weather forecasts to help farmers make timely planting decisions.
Research & Innovation: Invest in breeding TSWV-resistant tomato varieties and exploring biological control options.

6. Conclusion

TSWV remains a major threat to tomato farming in Ghana, but strategic adaptation based on weather trends can significantly reduce its impact. Collaborative efforts among stakeholders are essential to develop and implement effective control measures, ensuring sustainable tomato production and food security in Ghana.

Further information contact:

Dr Rebecca Sarku, Research Fellow in Climate Change and Food Systems
Alexander von Humboldt Postdoctoral Fellow
Email: r.sarku@yahoo.com