The Effect of Biochar on Plant Diseases: What Should We Learn While Designing Biochar Substrates?

Abstract

The increasing demand for soilless substrates and rising environmental concerns about the use of non-renewable resources such as peat has led to the search for alternative constituents of growing mixtures for containerized plants. In this report we reviewed the works concerning biochar as constituent of growing media, targeting its influence on plant growth and plant disease. Biochar mostly has positive or neutral influences on plant growth compared with peat media when present in concentrations higher than 25% (v:v). However, studies of biochar influence on plant disease reveals that while lower concentrations (≤1%) of biochar often suppressed several diseases, higher concentrations (≥3%) were mostly ineffective or induced plant disease. For use as horticultural peat replacement, it is recommended that biochar feedstocks and concentrations be standardized and the potential effect of biochar on plant disease be considered, so that growers can rely on consistent and reproducible biochars for desired effects.

Amending Sandy Soil with Biochar Promotes Plant Growth and Root Colonization by Mycorrhizal Fungi in Highbush Blueberry

“…Plants inoculated with P. cinnamomi developed root rot, regardless of whether the soil was amended with biochar or biocharbokashi. Other studies have reported that soil pathogens, such as Phytophthora sp., were suppressed by low concentrations of biochar in the soil, but higher concentrations were ineffective or, in some cases, accelerated plant disease (Copley et al, 2015;Frenkel et al, 2017;Jaiswal et al, 2015;Zwart and Kim, 2012). Perhaps the rates of biochar used in the present study were too high to suppress development of P. cinnamomi in highbush blueberry.…”

Impact of biochar properties on soil conditions and agricultural sustainability: A review

“…Moreover, biochar treated‐soil had raised pH and reduced chlorophyll content and soil available N. In a greenhouse experiment, Gu et al () concluded that biochar was efficient in reducing the bacterial wilt of tomato ( Ralstonia solanacearum ) by increasing chemotataxis ability of pathogen and suppressing the pathogen swarming mobility and root colonization. Moreover, recently a review study investigated that low amount of biochar (<1%) is considered effective in suppressing several plant diseases; but a higher rate of biochar (>3%), in most cases, is not effective or persuade plant diseases (Frenkel et al, ). Rogovska, Laird, Leandro, and Aller () indicated that two out of eight biochars significantly inhibited the severity of soybean root rot caused by Fusarium virguliforme under a greenhouse study, and further elucidated that suppression of root rot disease was not linked to the soil physico–chemical properties such as pH, bulk density, and soil moisture.…”

Biochar potential in intensive cultivation of Capsicum annuum L. (sweet pepper): crop yield and plant protection

“…To date, a biochar‐mediated influence has been shown for 15 different pathogens (fungi, oomycetes and nematodes) in 30 different pathosystems (i.e. plant/pathogen system) . The vast majority of these studied systems, however, have been small‐scale pot experiments.…”

“…plant/pathogen system). 27 The vast majority of these studied systems, however, have been small-scale pot experiments. The current study aims to test the influence of various biochars on the growth and disease resistance of Capsicum annuum L. (sweet pepper) under modern, high input, high yield, intensive net house cultivation over the course of several years (2011)(2012)(2013)(2014).…”