Effect of Mixed and Single Crops on Disease Suppressiveness of Soils

Abstract

The effect of mixed cropping on disease suppressiveness of soils was tested for two cropping systems, Brussels sprouts-barley and triticale-white clover. Disease suppressiveness of field soils was evaluated in bioassays for the soilborne pathogens Rhizoctonia solani, Fusarium oxysporum f. sp. lini, and Gaeumannomyces graminis var. tritici. For both cropping systems, mixed cropping did not enhance disease suppressiveness of the soils. In some cases, soil cropped to barley alone was significantly more suppressive to F. oxysporum f. sp. lini than soils cropped to Brussels sprouts or the mixture of Brussels sprouts and barley. Analyses of the diversity of the indigenous bacterial and fungal microflora by denaturing gradient gel electrophoresis of amplified 16S- and 18S-rDNA fragments, respectively, revealed, in most cases, no significant differences between mixed and mono-cropped soils. In conclusion, in this study, mixed cropping of soils with Brussels sprouts and barley or with triticale and white clover did not enhance microbial diversity or disease suppressiveness of soils to three different soilborne plant pathogens.

Biological Soil Disinfestation (BSD), a new control method for potato brown rot, caused by Ralstonia solanacearum race 3 biovar 2

“…Soil bacterial diversity was studied using polymerase chain reactiondenaturing gradient gel electrophoresis (PCR-DGGE). For DNA extraction, PCR and DGGE analysis, the methods described by Hiddink, Termorshuizen, Raaijmakers, and van Bruggen (2005) were followed, the main steps of which are described below. Total DNA was extracted from 0.5-g soil samples using the Bio101 FastDNAÒ SPIN Kit for Soil according to the manufacturer's specifications (Bio101, Vista, CA, USA) except that before the final centrifugation step the DNA extract was incubated for 20 min at 65°C for better DNA elution.…”

Potato brown rot incidence and severity under different management and amendment regimes in different soil types

“…For DGGE analysis of the eubacterial soil population, PCR amplification of the V6 to V8 region of the 16S rRNA gene from total soil DNA was conducted as described previously (Hiddink et al 2005). DNA extracts from rhizosphere were diluted ten times more than for bulk soil to have the same amount of extracted DNA (about 2 ng).…”

Impact of cover crop in pre-plant of apple orchards: relationship between crop health, root inhabiting fungi and rhizospheric bacteria

“…Conversely, the potential of cover cops in controlling soilborne fungal pathogens may be attributed to microbial diversity or to allelopathic compounds such as those released by Brassicaceae, which have given alternating results in open field (Peters et al 2003;Motisi et al 2013). This suggests that although vegetation cover deeply influences soil microbial communities (Chim Chan et al 2008;Ke et al 2015) and land use can induce a shift in composition of microbial communities (Drenovsky et al 2010;Suleiman et al 2013), little has been investigated on the possibility of increasing soil health by manipulating microbial communities of cultivated soils using cover crops (Mazzola 2007;Hiddink et al 2005). Therefore, a study on cover crops focusing on plantÁsoil microorganism interaction was performed to evaluate their potential for developing new cropping practices that are able to mitigate replant disease.…”