The use of Ka’a He’ẽ [Stevia rebaudiana (Bertoni) Bertoni] extract in the control of Septoria leaf spot and Bacterial spot of Tomato (Solanum lycopersicum L.)

Abstract

Septoria and Bacterial Spot Leaf are considered the most preponderant diseases due to reduction of 60% on tomato production, being the major constraints to sustainable production. In order to find control alternatives, it has been evaluated the effect of Ka’a He’ẽ extract on the severity of Septoria and Bacterial Spot Leaf, and the promotion of tomato growth performing two experiments at the FCA-UNA, conducted between July and December 2015. Experiment 1 was held to determine the content of chlorophyll, leaf area, height, root length and dry mass. It was applied 5 treatments with 4 replicates, on dose of 50, 150 and 300 mL L-1 of Ka’a He’ẽ extract, with an absolute control and a chemical one. On Experiment 2 it was quantified the severity caused by Septoria and Bacterial Spot on crop yield and °Brix of fruits. It was applied 6 treatments and 3 repetitions with increasing doses of the extract, and extract mix with chemical product, with an absolute control and chemical one. For both experiments, randomized block design was used. Obtained data was submitted to ANAVA, though Tukey test. The results indicate that the low doses of Ka’a He’ẽ extract present less severity of Septoria, increased leaf area, height, root length and dry mass of the plants. Medium doses decreased Bacterial Spot, while high doses increased chlorophyll content as well as crop yield. Moreover, extract combination with chemical product increased °Brix and decreased leaf diseases severity.