Abstract

RODRIGUEZ, Dorian A  and  SANABRIA, MarÍa E. Efecto del extracto de tres plantas silvestres sobre la rizoctoniosis, la mancha sureña del maíz y los patógenos que las causan. INCI [online]. 2005, vol.30, n.12, pp.739-744. ISSN 0378-1844.

To find safer alternatives to handle plant diseases, ethanolic extracts of Lippia origanoides, Phyllanthus niruri y Heliotropium indicum were evaluated on Rhictozonia solani y Bipolaris maydis as well as on the diseases caused by them on corn. The extract obtained from dry leaves was diluted in potato-dextrose-agar at concentrations from 0 to 10% (v/v) and dispensed into Petri dishes. A mycelial disc of each fungus was placed in the dishes, colony diameter measured and the percentage of inhibition calculated based on the growth of the control (0%). For in vivo evaluation, three tests were established with corn: a) inoculation with R. solani and weekly application of extracts diluted in water at 2.5%; lesion number and length were evaluated 18 and 26 days later; b) application of extracts 1h before or later of innoculation with B. maydis with lesion evaluation every 3 or 4 days; c) application of extracts 24h before or later of inoculation. Significant differences (P<0.01) were found between the concentrations used in the vitro test. L. origanoides (1%) and P. niruri (5%) extracts caused 100% and 90 % inhibitions, resoectively. A major effect of P. niruri and L. origanoides was observed on the control of rhictozonia disease. With regard to southern corn leaf blight P. niruri and L. origanoides performed better when applied 1h before inoculation. These results indicate the potential of the extract of the evaluated plants to control both diseases in corn

Keywords : Bipolaris maydis ; Rhizoctonia solani .