On-farm Validation of Coffea arabica and Aloe vera Extracts for Management of Seed-Borne Bacterial Leaf Spot Disease of Tomato

Abstract

In Tanzania, seed infection by bacterial leaf spot (BLS) pathogen (Xanthomonas perforans) causes yield losses up to 45% in tomato (Lycopersicon esculentumL.; Solanaceae family). Several studies have been conducted and wedged ecological organic agriculture (EOA) technologies (i.e., on botanicals/ biopesticides) which are significant to organic farmers in Tanzania. Nevertheless, these studies have been conducted in laboratory and greenhouse conditions, hence the technology cannot be disseminated to organic farmers for application before being validated. The current study was laid out as a 2x3 factorial experiment with five replications. Factor A was two common tomato cultivars “Rio grande” and “Malkia F1”, while factor B was seed treatment with three levels of crude plant extracts namely A. vera, C. arabica,and A. vera+ C. arabicaand untreated/control. To make the individual crude extracts, the roasted C. arabica beans powder (5g) and A. verajuice (5 ml) were mixed into 50 ml of clean water to get 10% weight/volume (w/v), respectively, while A. vera+ C. arabicacombination was obtain at a volume (ml) ratio (1:1). Tomato seeds were then soaked in 1 ml of the 10% w/v plant extracts for 12 hours, then air-dried for 1 hour before sowing. The highest efficacy against Xanthomonas perforanswas obtained from a combination of extracts from A. vera+ C. arabicaat volume (ml) ratio (1:1) hence, recommended for seed treatment. Organic tomato farmers need to adopt seed treatment practices that ensure seedlings’ start-up and enhance crop growth and productivity. Although the results of validation comply with the recommendations from previous research findings, further study is needed to evaluate the effectiveness of plant extracts subject to seasonal variability among the production areas.