Sclerotinia sclerotiorum is a soilborne fungus and causes white mold, sclerotinia cottony rot in lettuce (Lactuca sativa) and other crops. The control of this disease is very difficult, since that fungus produces resistance structures, the sclerodia. In the search of new methods for disease control, the plant extracts with therapeutical properties arise as a new option. The effect of aqueous crude extract (ACE) of ginger (Zingiber officinalis) was evaluated in vitro at concentrations of 1, 5, 10, 15, 20 and 25% on S. sclerotiorum mycelial growth and sclerodia production. The efficiency of ginger on the production of lettuce plants was also verified in plants and inoculated with the pathogen. Disease incidence, crop yield and peroxidase activity were analyzed in plant tissue. Water and the resistance inducer agent acibenzolar-S-methyl were used as control. Additionally, the ability of ACE in inducing accumulation of phytoalexins 3-deoxyanthocyanidin and glyceollin was evaluated in sorghum and soybean bioassays, respectively. The results showed the antimicrobial activity of ginger on the inhibition of mycelial growth and sclerodia production. In the lettuce crop, it was observed that the application of ginger mass on the soil close to plants basis increased of peroxidase activity and reduced disease incidence. The presence of elicitor compounds in the ACE was detected by the production of phytoalexins in sorghum and soybean, with dose-dependent responses. These results showed the potential of Z. officinalis on the control of S. sclerotiorum in lettuce that can occur by antimicrobial activity and defense mechanisms induction.
plant extract; alternative control of diseases; resistance induction