EFECTO DE EXTRACTOS BOTÁNICOS Y QUITOSANO SOBRE EL CONTROL DE LA PUDRICIÓN CAFÉ EN CORMOS Y PLANTAS DE GLADIOLO, CULTIVADAS EN INVERNADERO

Abstract

Fusarium oxysporum f.sp. gladioli causes rot corm and yellowing of gladiolus corms. In Mexico, the annual economical production of this crop is up to $800 mdp. The objective of this work was to evaluate methanolic extracts of red mombin, guava and nance on the control of F. oxysporum f.sp. gladioli over corms and gladioli plants. Leaves of each species were collected and they were washed, dried and grinded. The botanical powder was mixed with methanol in a proportion of 1:5. The extract was concentrated in a rotary evaporator at 65 °C. The botanical extracts were analyzed through gas chromatography and mass spectrophotometer (CG-EM) and 42 compounds were identified, that included monoterpenes, sesquiterpenes, diterpenes and fatty acids. For the greenhouse experiments, corms were inoculated with mycelia and spore solution and they were treated with the extracts at 2.5 and 5 %. They were planted in pots containing sterile or field collected soil. In experiment 1, corms treated with the nance and red mombin extracts at 2.5 % showed the lowest (8.5) and highest (14.5) emergency days (P≤0.025). In the treatment with guava at 5%, the flower spike was developed in 75% of the plants compared with the treatments with fungicide (33%) (P≤0.001). In experiment 2, the inoculated corms with spore solution and treated with extracts, germinated in less days and had less disease severity that the inoculated with mycelia (P≤0.001). In experiment 3, the treatment with nance at 2.5% (34.4 cm) and with fungicide (35.2 cm) showed the highest height in comparison with the remaining treatments (P≤0.001). The treatment with fungicide and with red mombin showed the lowest (2%) and highest (4.5) severity. In experiment 4, corms treated with guava and chitosan and planted in sterile soil, showed the lowest diseases incidence (33%). Overall, the planted corms in non-sterile soil germinated in fewer days, had less severity and reached the highest height than the plants in sterile soil. The botanical extract may be an alternative for managing the gladiolus fusariosis, perhaps for individual compounds or synergism of some of them.