Effect of soil type, organic matter content, bulk density and saturation on clubroot severity and biofungicide efficacy

Abstract

Growth room experiments were conducted to assess the interaction of soil type, biofungicides, soil compaction and pathotype/host on infection and symptom development caused by Plasmodiophora brassicae, the cause of clubroot on Brassica spp. In two initial experiments, four soil types (peat soil, mineral soil, non‐calcareous sand, soil‐less mix), two biofungicides (Bacillus subtilis, Clonostachys rosea), and two pathotypes (3 and 6, Williams’ differential set) were assessed. Differences in clubroot severity associated with soil type were unexpectedly small and variable. Prestop (C. rosea) was often more effective than Serenade (B. subtilis) at reducing clubroot levels on peat and mineral soils, but less effective than Serenade on sand. Inoculation with pathotype 3 often resulted in a slightly higher mean severity than pathotype 6. The interaction of soil type × biofungicide was similar on both canola (B. napus) and Shanghai pak choy (B. rapa subsp. chinensis), whether the soil was kept saturated or allowed to drain after inoculation. The impact of soil type on biofungicide efficacy might explain, in part, why biofungicides are more effective in one location than another. The observation that clubroot severity in soil‐less mix was affected by compaction led to an investigation of soil bulk density. Severity was higher in soil‐less mix that was more compacted than in the initial experiments, and was lower in peat and mineral soils when soil bulk density was reduced by adding soil‐less mix. In this study, soil bulk density had a larger impact on clubroot than soil type, organic matter or pathotype.

Relationships between plant diversity and soil microbial diversity vary across taxonomic groups and spatial scales

“…Negative impacts of BD on plant-microbial interaction are well-documented, particularly in agricultural soil (Young andRitz 2000, Beylich et al 2010). At the same time, BD could contribute to soil types' effects on plant-microbial interaction (Li et al 2002, Gossen et al 2016. At the same time, BD could contribute to soil types' effects on plant-microbial interaction (Li et al 2002, Gossen et al 2016.…”

“…More compact soil is likely impairing activity of both microbes and plants (Young andRitz 2000, Beylich et al 2010). At the same time, BD could contribute to soil types' effects on plant-microbial interaction (Li et al 2002, Gossen et al 2016. Depending on the dominant plant community (e.g., grasses vs. trees, and annuals vs. perennials), variations in root system might modify soil structure, which in turn contributes to its own turnover (Cook and Hesterberg 2013).…”

Bacterial composition in brassica‐cultivated soils with low and high severity of clubroot

“…As the chemical and genetic control of clubroot is still restricted, management practices such as crop rotation, elevation of pH and Ca levels and adequate management of soil moisture are the most important strategies to reduce the losses caused by the disease (Santos et al, 2020; Bhering, Carmo, Matos, Lima, & Sobrinho, 2017; Gossen, Kasinathan, Deora, Pengm, & Mc Donald, 2016; Dixon, 2014). Most control strategies aim to affect the P. brassicae phase in the soil, either by reducing the number or viability of resting spores or by inhibiting its germination or the activity of the primary zoospores, liberated with resting spores germination.…”

Crop production kept stable and sustainable with the decrease of nitrogen rate in North China Plain: An economic and environmental assessment over 8 years

“…Soil physical properties, bulk density and water-stable aggregates were measured after harvesting summer maize in 2015 and 2016. The samples from undisturbed soil for 0–30, 30–60, and 60–90 cm layers were collected using a steel cylinder of 100 cm 3 volume (5 cm in diameter, and 5.1 cm in height) to determine bulk density 31 . Soil samples were taken in 0–30, 30–60 and 60–90 cm layers, respectively, using a metal cylinder with diameter of 25 cm, from three randomly selected spots each plot.…”