Fusarium oxysporum causa pérdidas en la producción de tomate, para su control se emplean fungicidas químicos que afectan el medio ambiente y causan problemas de resistencia; por lo que se han desarrollado alternativas como los extractos vegetales. El objetivo del presente trabajo fue evaluar la efectividad biológica de extractos de plantas del semidesierto mexicano contra F. oxysporum bajo condiciones de invernadero. Los tratamientos fueron: T1 = A. lechuguilla hoja (250 mg L-1), T2 = C. illinoinensis ruezno (250 mg L-1), T3 = L. graveolens hoja (500 mg L-1), T4 = L. graveolens tallo (125 mg L-1), T5 = testigo químico, T6 = testigo absoluto (inoculado) y T7 = control; a los que se les evaluó la incidencia y severidad de la enfermedad, y variables morfométricas. Se observó disminución de la incidencia y severidad de la enfermedad con extractos de A. lechuguilla hoja y L. graveolens tallo, además de un mayor desarrollo en parámetros morfométricos de las plantas.
Introduction: In several regions of the world, Fusarium oxysporum causes losses on tomato crops; for control it, chemical fungicides are used. Nevertheless, these fungicides causing environmental and resistance problems; therefore, ecological alternatives as plant extracts have been developed. Due to the aim of this work, identify phytochemicals present in ethanolic and aqueous extracts from Agave lechuguilla qualitatively, Carya illinoinensis, Jatropha dioica, Larrea tridentata, and Lippia graveolens and determine their antifungal activity against F. oxysporum.Method: The plants collected from the northeast of Mexico; crudes and concentrated plant extracts obtained; the inhibition percentage and inhibitory concentration to 50 % (IC50) of F. oxysporum for each plant extract were determinate trough microdilution in the plate methodResults: The essential phytochemicals were flavonoids, saponins, tannins, and quinones. The antifungal activity showed at 1000 mg/L inhibition around 40 to 60% by aqueous crude extracts from leaves of L. graveolens and concentrated aqueous extracts from the stem of L. graveolens, respectively. The ethanolic extracts presented 100 % of inhibition for crude extracts of husk from C. illinoinensis; in leaves and stem from L. graveolens the inhibition started from 250 mg/L; for resuspended extracts, the inhibition started from 125 mg/L with L. graveolens stem and leaves; and finally in roots of A. lechuguilla and leaves from L. graveolens the inhibition started from to 250 and 500 mg/L respectively. The best IC50 was of 8.02 mg/L from the ethanolic resuspended extract of L. graveolens stem.Conclusion: The ethanolic plant extracts from L. graveolens, A. lechuguilla, and C. illinoinensis, showed 100 % of inhibiting activity against the development of F. oxysporum, representing an alternative for control of F. oxysporum.
This chapter will cover topics about the microbial antagonists Trichoderma spp. and Bacillus spp. from the perspective of use as potential biological control agents on plant diseases. Results obtained in the laboratory about from their isolation, microbial strain collections for both genera, taxonomic identification, antifungal activity in in vitro tests, obtained evaluation of the antifungal effect of secondary metabolites from microbial antagonists will be shown. Besides, results obtained from bioassays in the greenhouse and field are used as biopesticides in the control of diseases in fruit trees and vegetables and their effects on the promotion of plant growth and increased crop yield.
Plant extracts (PEs) and essential oils (EOs) contain phytochemical compounds (PCs). Nevertheless, PCs can be degraded when applied on field. The use of nano-encapsulates (NEs) and micro-encapsulates (MEs) arise as an alternative to the application of botanical products. However, NEs and MEs with PCs in plant disease control have not been explored enough. This review discusses the use of PCs for plant disease control and the benefits obtained from formulations with NEs and MEs; furthermore, it discusses methods to produce NEs and MEs.
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