Control of spot blotch in barley plants with fungicide and Bauhinia variegata Linn. leaf extract

Abstract

In barley plants (BRS-195), the disease detected as spot blotch is caused by Bipolaris sorokiniana, and is the most deleterious disease for the producers and the beer industry. For fungicides mediated control of this disease can cause risks to environment and human health. To eliminate these drawbacks, one of the methods considered is the use natural products. The purpose of the present study was to investigate the use of extract of leaves from Bauhinia variegata Link. and Opera® fungicide (active ingredient: pyraclostrobin) for controlling Bipolaris sorokiniana in barley plants. In Brazil there are two species of Bauhinia are seen, namely Bauhinia forficata and B. variegate. Extracts from B. variegata didn't show fungitoxic action but B. forficata the action exist. The barley plant showed protection of 92 to 100% in local and systemic action. The chemical TLC assays showed the presence of phenols (rutin, coumaric acid, kaempferol) that can be related to a signal for activation of the defense responses against pathogen or mechanism of salicylic acid. Treatment with fungicide Opera® gave another mechanism and have only 60% of protection.