Effect of mulch and different pre-harvest fungicide spray regimes on shelf life of tomato (Solanum lycopersicum L.) in Tanzania

In Tanzania, farmers excessively spray fungicides in order to improve tomato fruit shelf life. In this study the effect of three pesticide spray regimes on tomato shelf life was evaluated. The spray regimes included; farmers’ practice (FP), spray when needed after scouting (IPM) and spraying as per manufacturers’ recommendation (MR). The effect of mulch on shelf life of tomato was also studied. ‘Tanya VF’ and ‘Tengeru 97’ tomato varieties were used in this study. Field experiment consisting of a 2×2×4 factorial arrangement in a split-split plot design with three replications was conducted. Treatment factors comprised two varieties (main plot factor), mulching (subplot factor) and three fungicide spray regimes (sub subplot factor). The laboratory experimental layout was a CRD with three replications. The laboratory had a max/min temperature of 31o/19oC. Shelf life assessment was done weekly for six weeks. Results show that fruits loss under the three fungicide application regimes was lower (p < 0.001) compared to the control during the first week. MR reduced fungicide sprays by 100% compared to FP with no significant reduction in shelf life. In the second week shelf life of fruits from plants under IPM and MR were similar (p = 0.05) but differed with the control. However, FP spray regime had significantly (p = 0.005) longer shelf life. The use of mulch led to fruits with consistently longer shelf life for four weeks in storage (p = 0.001, p = 0.008, p < 0.001, p = 0.037, respectively). Considering the two varieties, ‘Tengeru 97’ consistently had lower (p < 0.001) fruit loss throughout the storage duration compared to ‘Tanya VF’. It was also revealed that, harvesting at different maturity stages had significant influence (p < 0.001) on fruit shelf life. Harvesting at breaker stage is advantageous since there was low postharvest fruit loss encountered.

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