Suppression of Pythium ultimum by Biowaste Composts in Relation to Compost Microbial Biomass, Activity and Content of Phenolic Compounds

Abstract

Seventeen composts from separately collected organic household waste plus one bark compost and one compost from grape marc were analysed for suppression of Pythium ultimum\ phytotoxicity\ microbial biomass and activity\ substrate!induced respiration\ extractible phe! nolic compounds and other physical and chemical par! ameters[ Nine of the samples were mildly suppressive to P[ ultimum\ the others were conducive[ The bark compost sample was strongly suppressive[ Therefore of the exam! ined composts\ only the bark could be used to exert an economically relevant control of P[ ultimum in hor! ticultural media[ A large part of the compost samples was slightly phytotoxic[ Microbial biomass and SIR had only weak correlations with disease incidence[ Microbial activity and content of extractible phenolics were posi! tively correlated with disease incidence[ None of the tested parameters were therefore suitable as a predictive test for suppression of P[ ultimum with the compost sam! ples used in this study[ Zusammenfassung Unterdru Ãckung von Pythium ultimum durch Biotonnekomposte in Beziehung zu mikrobieller Biomasse und Aktivita Ãt sowie zum Phenolgehalt Siebzehn Biotonnekomposte sowie ein Rindenkompost und ein Traubentresterkompost wurden auf ihre Fa Ãhig! keit\ Pythium ultimum zu unterdru à cken\ getestet[ Weiteres wurden die P~anzenvertra Ãglichkeit der Komposte\ ihre mikrobielle Biomasse und Aktivita Ãt\ substratinduzierte Respiration\ lo à sliche Phenole und weitere physikalische und chemische Parameter untersucht[ Neun der siebzehn Proben waren leicht suppressiv gegenu à ber Pythium ulti! mum\ die anderen konnten den Pathogen nicht unterdru à c! ken[ Der Rindenkompost hatte stark suppressive Wirkung[ Von den untersuchten Komposten ko à nnte nur der Rindenkompost fu à r die Unterdru à ckung von P[ ulti!

Effects of irrigation with treated agro-industrial wastewater on soil chemical characteristics and fungal populations during processing tomato crop cycle

“…Several studies have reported tight correlations between the natural suppressive capacity of the soil, the level of microbial populations, and the OM content (Erhart et al, 1999; According to a previous report (Abawi and Widmer, 2000), wastewater used for irrigation can also affect the microbial diversity in the soil, including the relationships among the different species in terms of suppression of plant pathogens such as F. oxysporum, which is responsible for plant vascular diseases.…”

The rhizosphere: a playground and battlefield for soilborne pathogens and beneficial microorganisms

“…To date, compost amendment has been successfully used to increase soil suppressiveness to diseases in agricultural crops, including nematode diseases (Erhart et al 1999;Lumsden et al 1983;Oyarzun et al 1998;Serra-Wittling et al 1996;Steinberg et al 2004;Widmer et al 2002), as well as disease suppression in horticultural crops (Cotxarrera et al 2002;Hoitink and Boehm 1999). The mechanisms involved, however, are not fully understood yet and subject of ongoing studies.…”

Organic Amendments to Avocado Crops Induce Suppressiveness and Influence the Composition and Activity of Soil Microbial Communities

“…Many authors have correlated the suppression of certain plant diseases with organic parameters related to physicochemical properties (28,29), microbial biomass (30,31), microbial diversity (23,32), microbial community composition (33,34), microbial overall activity (30,35), metabolic and enzymatic profiles (34,36), and particular enzymatic activities (37,38). Even if certain of these parameters are better predictors than others, none is universally related to disease suppression, and their correlation with suppressiveness is largely dependent on the pathosystem, the type of amendment used, and the environmental conditions (26,27).…”