Patterns, Practices, and Socio-Environmental Dynamics of Pesticide Use in the Horticultural Value Chain: Insights from Smallholder Farmers and Agro-Input Sellers in Iringa and Njombe, Southern Highlands, Tanzania

Background: The use of pesticides among smallholder farmers, agrochemical sellers, and agricultural officers involves a complex interplay of knowledge, economic factors, and regulatory frameworks. Therefore, this study explores the patterns, practices, and socio-environmental dynamics of pesticide use among smallholder farmers and agro-input sellers in Iringa and Njombe. Method: This study employed a qualitative, phenomenological design, guided by the socio-ecological model (SEM), to explore the lived experience of farmers, agro-dealers, and extension officers. It involved a total of 23 interviews performed in the Njombe and Iringa regions. Data were collected between October 2024 and March 2025, using a combination of in-depth phenomenological interviews, key informant interviews, and field observations, and were categorized into themes and subthemes analyzed using InVivo. Results: The study involved a total of 23 participants drawn from the Iringa and Njombe regions. The gender distribution was nearly balanced, with 52.1% male and 47.8% female respondents. The mean age of participants was 33 years (95% CI: 29.3–37.3). In terms of education, over half (52.17%) had completed primary school. The findings show that smallholders in Iringa and Njombe widely use mixed pesticides and fertilizers, rely on trusted brands, and adapt to climate impacts, but face challenges with regard to unsafe mixing, poor storage, fake products, and weak regulation, highlighting the need for better education, market oversight, and safer practices. Conclusion: Using the socio-ecological model, the findings indicate that pesticide use among smallholder horticultural farmers in Iringa and Njombe is influenced by a complex interaction of socio-economic constraints, market forces, climate variability, and institutional shortcomings. Although farmers have some awareness of safe practices, systemic barriers continue to limit the adoption of sustainable pesticide management.