Verticillium wilt is the most severe diseases of olive worldwide. The pathogen, Verticillium dahliae Kleb., is able to persist for several years in contaminated soils by its resting structures represented by the microsclerotia (MS). In the last decades the disease has occurred with increasing frequency and severity in most olive-growing areas, particularly on young plants in the nursery as well as in the field. The disease control by means of synthetic fungicides involves several risks and then safer and more eco-compatible control measures are necessary. Preventive methods (i.e. pathogen-free soil and planting material, suppressive substrates and biocontrol agents) have been shown as promising tools for anefficient control ofthe pathogen in the nursery. Recently, alternative plant growth substrates containing natural amendments or composted biomasses are being studied notonly for agronomic properties, but also for their suppressiveness against soil-borne pathogens. To prevent V. dahliae infections our investigations were conducted for one year in growth chamber and for two year in a commercial olive plant nursery with self-rooted olive plants, cv Leccino. Trials were aimed at evaluating the suppressive activity against V. dahliae MS of some organic amendments, obtained from vegetal by-products, and antagonistic bacteria isolated from these suppressive matrices. The experimental matrices at 15% (v/v) weremixed in different proportion with a standard substrate (“Sonnoli”) while experimental bacteria were applied at a concentration of 10 9 cfu g -1 . The experimental substrates were artificially contaminated with 50-100 MS/g. In blind trial experiments, the pathogen was periodically monitored in the soil by either semi-selective medium or real-time Scorpion PCR. The effect of the treatments on the plant growth was also evaluated. Results of experiments evidenced thatsome experimental matrices and antagonistic microorganisms significantlyreduced the inoculums density of V. dahliae MS in the rizosphere of olive plantsand did not interfere with the plant growth. The mechanisms of compost suppressiveness were mainly related to their natural content of antagonistic microflora. The new substrates and antagonists are worthy to be optimized as new and safer alternatives to chemicals for the prevention of V. dahliaeinfections in the rhizosphere of nursery-grown olive plants.

Effect of cured compost and biocontrol agents on the viability of Verticillium dahliae microsclerotia in the rhizosphere of nursery-grown olive plants

LIMA, Giuseppe;DE CURTIS, Filippo;
2009-01-01

Abstract

Verticillium wilt is the most severe diseases of olive worldwide. The pathogen, Verticillium dahliae Kleb., is able to persist for several years in contaminated soils by its resting structures represented by the microsclerotia (MS). In the last decades the disease has occurred with increasing frequency and severity in most olive-growing areas, particularly on young plants in the nursery as well as in the field. The disease control by means of synthetic fungicides involves several risks and then safer and more eco-compatible control measures are necessary. Preventive methods (i.e. pathogen-free soil and planting material, suppressive substrates and biocontrol agents) have been shown as promising tools for anefficient control ofthe pathogen in the nursery. Recently, alternative plant growth substrates containing natural amendments or composted biomasses are being studied notonly for agronomic properties, but also for their suppressiveness against soil-borne pathogens. To prevent V. dahliae infections our investigations were conducted for one year in growth chamber and for two year in a commercial olive plant nursery with self-rooted olive plants, cv Leccino. Trials were aimed at evaluating the suppressive activity against V. dahliae MS of some organic amendments, obtained from vegetal by-products, and antagonistic bacteria isolated from these suppressive matrices. The experimental matrices at 15% (v/v) weremixed in different proportion with a standard substrate (“Sonnoli”) while experimental bacteria were applied at a concentration of 10 9 cfu g -1 . The experimental substrates were artificially contaminated with 50-100 MS/g. In blind trial experiments, the pathogen was periodically monitored in the soil by either semi-selective medium or real-time Scorpion PCR. The effect of the treatments on the plant growth was also evaluated. Results of experiments evidenced thatsome experimental matrices and antagonistic microorganisms significantlyreduced the inoculums density of V. dahliae MS in the rizosphere of olive plantsand did not interfere with the plant growth. The mechanisms of compost suppressiveness were mainly related to their natural content of antagonistic microflora. The new substrates and antagonists are worthy to be optimized as new and safer alternatives to chemicals for the prevention of V. dahliaeinfections in the rhizosphere of nursery-grown olive plants.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11695/18235
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