Open Access is an initiative that aims to make scientific research freely available to all. To date our community has made over 100 million downloads. It’s based on principles of collaboration, unobstructed discovery, and, most importantly, scientific progression. As PhD students, we found it difficult to access the research we needed, so we decided to create a new Open Access publisher that levels the playing field for scientists across the world. How? By making research easy to access, and puts the academic needs of the researchers before the business interests of publishers.
We are a community of more than 103,000 authors and editors from 3,291 institutions spanning 160 countries, including Nobel Prize winners and some of the world’s most-cited researchers. Publishing on IntechOpen allows authors to earn citations and find new collaborators, meaning more people see your work not only from your own field of study, but from other related fields too.
Biochar is a potential alternative management tool for diseases caused by soilborne pathogenic Fusarium and Phytophthora, respectively fungus and oomycete. Currently there are only general reviews for biochar applications against plant pathogens without emphasis on Fusarium and Phytophthora. Globally, soilborne Fusarium and Phytophthora are economically important pathogens that severely impact agriculture and forestry industries. Our present review focuses on biochar treatment against soilborne Fusarium and Phytophthora, biochar mechanism for Fusarium and Phytophthora suppression, and feedstock effect on biochar efficacy. Biochar applications alter the rhizosphere or soil environment which impedes the survival and reproduction of soilborne Fusarium and Phytophthora pathogens. Unlike other disease control approaches such as fungicides applications or fumigation that directly target the cell-wall and other structures in Fusarium and Phytophthora soilborne pathogens, biochar has different mechanisms of action. Over the years, majority of research have focused on biochar treatments against soilborne Fusarium or Phytophthora pathogens under controlled conditions but not field trials. While biochar has several advantages, evidence-based research is required to understand its impact on the environment. Future research areas for biochar includes evaluating applications for different farming systems, biochar efficacy ratings and validating application rates against Fusarium and Phytophthora soilborne pathogens.
Resilient Agriculture, AgResearch Ltd., Grasslands Research Centre, Palmerston North, New Zealand
Goldy De Bhowmick
Smart Foods and Bioproducts, AgResearch Ltd., Te Ohu Rangahau Kai, Palmerston North, New Zealand
Adnan Akhter
Faculty of Agriculture Sciences, Department of Plant Pathology, Quaid-e-Azam Campus, University of the Punjab, Lahore, Pakistan
Muhammad Taqqi Abbas
Faculty of Agriculture Sciences, Department of Plant Pathology, Quaid-e-Azam Campus, University of the Punjab, Lahore, Pakistan
*Address all correspondence to: kwasi.adusei-fosu@agresearch.co.nz
1. Introduction
Soilborne pathogens are a huge problem for agriculture production [1] because they are hidden enemies of plants and offer greater challenge in their management. Among all known major plant diseases, soilborne pathogens alone are responsible for 90% of them [2]. Among soilborne pathogens, Fusarium and Phytophthora are considered as the most damaging plant diseases that threaten agriculture and forestry [3, 4, 5]. Globally, agriculture and forestry form the backbone of food security and economic growth [6, 7]. Therefore, it is important for Fusarium and Phytophthora soilborne pathogens to be managed. Fusarium species are well known to put economic burden or losses on the farming community [8] e.g., Fusarium oxysporum which is considered fifth most destructive persistent fungal pathogen [6]. Recent study reported the global impact of Fusarium spp. because the pathogen has a wide host-range presently in five major continents including Asia, Australia, North America, South America and Europe (Muhammad et al. 2023). Phytophthora is an emerging threat to the forest and horticulture sectors [9]. Soilborne Phytophthora species has been reported to cause 100% yield losses in some crops such as soybean [10].
Soilborne pathogens impact crop yields by infecting plants via their roots, causing wilting, discolouration and in some cases death of the plant. Soilborne pathogens reduce the value of agricultural lands because soilborne pathogens such as Fusarium can live in soil for over four decades [11, 12, 13]. This long-term effect of soilborne pathogens on the soil cause farmers to adopt land rotation farming system, but for locations where land is scarce, it becomes a daunting task. Over the years, chemicals (e.g., fumigation and fungicides) have been employed to control soilborne pathogens such as Fusarium and Phytophthora which are fungus and oomycetes, respectively [14, 15].
Chemicals are the main stay of farmers to manage diseases caused by Fusarium and Phytophthora spp. [16]. Different fungicides such as prochloraz, bromuconazole, benzamides, phosphonate, quinones are applied against Fusarium or Phytophthora soilborne pathogens based on their mode of actions and chemical properties [17]. However, an imperative drawback for fungicide treatment is the development of resistance in Fusarium and Phytophthora [18, 19]. Due to detrimental effects of chemicals on the environment and health of humans [20], there is the appetite for alternative tools to control soilborne diseases caused by Fusarium and Phytophthora.
Some ‘natural enemies’ or biological control agents such as Trichoderma spp., Burkholderia cepacia, Pseudomonas spp., plant growth-promoting rhizobacteria (PGPR) and arbuscular mycorrhizal fungi are also used to mitigate the losses caused by Fusarium and Phytophthora [21, 22]. However, the success of biological control depends not only on plant-microbial interactions, but also on the ecological fitness of the biological agents [23]. Identifying a soilborne disease control tool that would fine-tune soil physicochemical properties to suppress Fusarium and Phytophthora will be important for the agriculture industry. Biochar has been reported to modify soil physical, chemical, and biological properties to suppress soilborne pathogens [15, 24]. Therefore, application of soil organic amendments such as biochar serves as an alternative disease management option [25] against plant pathogens and diseases.
Biochar is a carbonaceous material derived from pyrolysis of biomass at temperatures 300–700°C under restricted oxygen supply [26]. The average carbon content of biochar lies between 70 and 80% and comprised of aromatic carbon structures including a crystalline phase and an amorphous phase. The crystalline phase is reformed as fused polyaromatic hydrocarbon sheets, and the amorphous phase is formed as random aromatic rings [26]. The carbon structure in biochar is a well-developed porous structure with various active surface functional groups, imparting multifunctional agricultural solutions most importantly, improving soil and plant health [27, 28]. Biochar is a known carbon-negative material [27], used for remediating polluted soil and water bodies, and has carbon reduction benefits [27, 29, 30, 31, 32, 33, 34] with strong positive influence on climate change through limitation of emissions of greenhouse gases [30, 35, 36].
Generally, biochar is used as soil amendment and there have been several reports that demonstrated improvements in soil–plant health [35, 36, 37, 38, 39]. Biochar application provides favourable soil conditions such as pH [29, 40], water holding capacity, nutrient supply (calcium-Ca, phosphorus-P, potassium-K, Nitrogen-N), cation exchange capacity (CEC) [29], the growth of beneficial bacteria [40] which enhances the overall soil and plant health. In addition, biochar does increase crop yield or biomass which has been demonstrated in maize [41], pepper [42], asparagus [43, 44], tomato [25], beans [45] and ryegrass [36].
In this review we have highlighted the application of biochar against Fusarium and Phytophthora soilborne pathogens from published literature (Figure 1). We have also discussed the effect of the pyrolysis process that influences the physicochemical composition biochar to enable disease management when used for soil treatments. Furthermore, we have highlighted the challenges associated with biochar applications under different agriculture production or farming systems.
Figure 1.
Biochar production process flow chart and application.
2. Discussing the mechanisms of biochar in soilborne pathogen management
Thermochemical methods such as pyrolysis, gasification, hydrothermal liquefaction and torrefaction are used to convert organic matter of biomass into solid carbon residue biochar [46], but pyrolysis has gained more attention in the recent times because it yields byproducts including solid biochar [21, 46]. Previous studies have shown that pyrolysis temperature, duration, heating rate, vapour residence time, pyrolysis type, feedstock composition, and feedstock material/biomass properties including biomass type, moisture, and particle size play a pivotal role in influencing the physicochemical properties of biochar [21, 46].
Temperature used for pyrolysis has been reported to influence biochar properties with subsequent impact on soil. An increase in pyrolysis temperature increases the C, P, K, Ca, ash content, pH, and surface area of biochar, whiles decreasing N, H, and O content [47]. The structure of biochar obtained from high-temperature pyrolysis is distinguished by a substantial surface area and aromatic carbon content. On the other hand, soil treated with biochar produced via pyrolysis at low temperature yields high volatile and readily decomposable substrates which promote plant development [48]. The increase in pH is mostly triggered by breakdown of hydroxyl bonds present within the feedstock material under high pyrolysis temperature [49]. Such phenomenon also suggests the availability of weak bonds within the feedstock and their vulnerability towards thermal decomposition [49]. Generally, slow pyrolysis produces biochar with greater N, S, available P, Ca, Mg, surface area, and cation exchange capacity (CEC) in comparison to fast pyrolysis [47]. The surface area increases significantly due to the decomposition of organic matter, and destruction of aliphatic alkyls, esters, and the aromatic lignin core thereby reducing the pre-blocking substances and by increasing the externally accessible surface area [50, 51]. In some of the studies it was also observed that at temperatures lower than 500°C, the lignin is not fully converted to a hydrophobic polycyclic aromatic hydrocarbon (PAH) thereby increasing the hydrophilicity of the biochar [50, 51]. Thus, at temperatures higher than 650°C, biochar’s are more hydrophobic and are thermally stable [50, 51]. The relationship between CEC and pyrolysis temperature was reported in previous studies and illustrated that with the increasing pyrolysis temperature CEC decreased linearly.
The physicochemical characteristic of biochar is determined by the initial feedstock and the pyrolysis conditions (heating temperature and time) [52]. Determining the best use for biochar requires comprehensive knowledge of the whole manufacturing process. Detailed physical, chemical characteristics and elemental composition of the biochar derived from different feedstocks have been researched by others [53]. The physicochemical characteristics of biochar have the potential to modify the availability of nutrients and carbon in the soil, as well as shield microorganisms from desiccation and predators. These changes might impact the soil’s microbial diversity and taxonomy [38].
The pyrolysis temperature could yield different physicochemical properties of the biochar based on the feedstock type used. For instance, biochar’s produced from woods, biosolids, and herbaceous feedstock demonstrated a neutral to slightly acidic pH upon lowering the pyrolysis temperature to under 400°C [49]. The variation in feedstock composition significantly affects the biochar properties including the elemental content (C, H, N, and S), yield, ash content, functional groups, aromaticity, porosity, specific surface area. According to [54], soil treated with biochar made from woodchip produced higher saturated hydraulic conductivities than those treated with manure-based biochar [55]. Similarly, manure-based biochar has a higher soil cation exchange capacity (CEC) than wood (Eucalyptus) biochar. To efficiently utilise majority of available biomass, the feedstocks are categorised into 1st to 3rd generation including lignocellulosic plants and energy crops, and algae. Recently, a fourth generation of biomass are being used widely includes organic waste such as coffee grounds, fruit peels, and sewage sludge [56, 57, 58, 59, 60, 61]. Among the agricultural crop residues and woody biomass category corn stalks, wheat stalks, straw, rice husk, potatoes, soybeans, sugar cane, bagasse, cotton, oranges, grapes, peanuts, rapeseeds, etc. were explored for biochar production [56, 57, 58, 59, 60, 61]. Previous studies revealed that biochar’s made from agricultural wastes were mostly alkaline in pH under similar pyrolysis conditions.
In summary the effect of pyrolysis and feedstock types could enhance the biochar properties and subsequent positive impact on soil when used as a supplement. For instance, the CEC of biochar was associated with the disappearance of some acidic functional groups when pyrolysis temperature was increased [62]. Others have also reported that pyrolysis exhibited high porosity with longitudinal pores of sizes ranging from micro to macropores and the macropores were originated from vascular bundles of raw biomass that could provide habitats for symbiotic microorganisms promoting soil health [51]. The cellulose, and lignin present in the feedstock (crop residues) is reported to potentially decay into smaller fragments resulting in lower O/C and H/C [62]. However, in case of woody biomass the differences in hemicellulose, cellulose, and lignin proportions further affects the elemental composition with low ash, low moisture, high calorific value, and few voids.
2.1 Biochar treatments against soilborne pathogenic Fusarium
Fusarium is a cosmopolitan fungus and could be either soilborne or foliar pathogen [63]. They spread via the production of spores (conidia or microconidia), which act as the infecting materials as well as reproductive structures. These spores typically exist in either a haploid or dikaryotic vegetative stage [64]. Some soilborne Fusarium spp. are known to be host specific, whereas others have a broad host range. Fusarium research over the past 100 years has improved our understanding about the relevance of this fungi group, but there are still some unknowns regarding its biology that must be addressed [63]. Gaining better understanding of the biology will provide information to develop precise and reliable control tools against the Fusarium pathogen which are difficult to manage.
Soilborne Fusarium pathogens are very difficult to manage [65]. Others have resorted to control tools such as fumigation and fungicides treatments against soilborne Fusarium pathogens [14], but these methods are considered not environmentally friendly or sustainable. Chemicals usually directly target parts of the soilborne pathogens including cell-wall and other structures whiles contaminating the soil. However, developing sustainable methods that would not contaminate soil but modify its properties such as soil pH, nutrients supply/availability/mobility and beneficial microbial populations to inhibit pathogenic Fusarium spp. from thriving is an alternative sustainable method. For instance, it has been demonstrated that some soil amendments regulated soil pH and nutrient supply which contributed to the successful management of Fusarium oxysporum f. sp. spinaciae in spinach fields [14].
The application of biochar has been reported to suppress several pathogenic Fusarium spp. [25, 43, 44, 66, 67, 68]. A case study reported that biochar has been tested mostly against fungi soilborne pathogens including F. oxysporum f.sp. radicis lycopersici, followed by F. oxysporum, F. solani and Fusarium spp. [37, 69].
Earlier research shows that a commercial prototype biochar produced by fast pyrolysis of hardwood dust successfully reduced the damaging effect of allelopathy on arbuscular mycorrhizal (AM) root colonisation and on Fusarium crown and root rot of asparagus under greenhouse conditions [44]. Similar studies were done in greenhouses to determine biochar efficacy against F. proliferatum in infested soils collected from field and results showed that root lesions were reduced in the soil treated with biochar [43]. Others have demonstrated soilborne F. oxysporum f.sp. lycopersicichlamydospores were suppressed via amendment of soil with biochar produced from feedstocks including wood chip and green waste biochar [25, 66].
A rare experiment in field determined efficacy of biochar produced from poultry faecal waste and sawdust against pathogenic F. verticillioides causal organism for ear rot in maize, using biochar treatment combinations as soil amendments. Biochar from sawdust effectively managed the disease compared with poultry faecal waste [70]. Recent studies showed that biochar made from organic wastes for soil amendment significantly decreased the colonisation and survival of F. oxysporum f. sp. vasinfectum in potted cotton plant under controlled conditions [71].
Advances made in production of biochar has been the coupling of biochar with other microbial inoculants to provide multiple benefits to plants and soil. Most recently, several studies have shown that biochar produced from feedstock such as bone charcoal, wood chip mixed with garden waste residue or cassava, coupled with microbial inoculants including strains of Pseudomonas chlororaphis, Paenibacillus polymyxa, Streptomyces pseudovenezuelae, Arbuscular mycorrhizal fungi, and Trichoderma aureoviride, suppressed pathogenic F. solani, F. oxysporum f.sp. radicis lycopersici in soil [72]. Identifying an approach to develop appropriate coupling materials to improve the biochar efficacy against Fusarium soilborne is very important for plant protection.
2.2 Biochar treatments against soilborne pathogenic Phytophthora
Phytophthora is an oomycete and could be soilborne or foliar pathogen. They mainly spread via the movement of infested soil, water, or plants using their two flagella that enhance swimming ability of zoospores [73]. The vegetative stage of oomycetes is diploid [64] and have cellulose in its cell walls [74]. Phytophthoras are known to have a wide host range [75], however, there are other host specific species such as the Phytophthora agathadicida [76] among others. Most agricultural practices rely heavily on chemicals for the management of Phytophthora soilborne pathogens. Applied chemicals target the cell walls of these pathogens but due to the difference in oomycete cell wall structure, a different strategy is required to control oomycetes diseases [77]. Thus, if targeting the pathogen directly has existing challenges, then other mechanisms of controlling phytophthora species via altering the soil environment would be a promising method such as biochar treatments.
There is lack of information on the use of biochar to treat Phytophthora pathogens. A few studies have reported its effectiveness in controlling several Phytophthora soilborne pathogens including P. cinnamomi, P. capsici, P. cactorum via soil amendment with biochar [42, 78, 79]. Earlier research explored the effect of biochar on P. cinnamomi and cactorum and suggested that biochar amendment has the potential to alleviate disease progression and physiological stress caused by phytophthora canker pathogens [78]. In addition, they reported that there is likely an optimal level of biochar incorporation into the root media, beyond which its beneficial effects may be less pronounced [78].
Other trials have been conducted to determine whether two commercially available biochar amendments could suppress P. capsici infection in sweet bell pepper (Capsicum annuum) using three naturally infested field soils. Their research showed that amending soil with a biochar product containing a proprietary mix of beneficial microorganisms and enriched substrates resulted in a lower soil P. capsici abundance in all soils, and low root infection in two of the three soils tested. This treatment also led to increased soil pH, lower soil nitrogen availability, and reduced leaf chlorophyll content [79]. Recent research has demonstrated that biochar treatments effectively inhibited pathogen growth and controlled P. capsici, with biochar applied immediately before planting having greater effects than that applied 20 days before planting [42]. Further trials compared the control treatments with biochar-amended rhizosphere soils and reported that biochar treated soil had higher pH levels, more available nutrients (e.g., P and K) and higher abundance of beneficial fungi that led to the suppression of P. capsici [42]. There is less information for field application of biochar against pathogenic Phytophthora. As it stands all the research with biochar treatments against Phytophthora have mainly been conducted under controlled conditions [42, 69, 78, 79]. It is also evident that most of the commercial and newly developed biochar products have not been tested against phytophthora on a commercial scale. This is concerning because farmers need to rely on research data to make informed decisions regarding the use of biochar products against Phytophthora soilborne pathogens. In a recent case study, it was reported that biochar has been tested against only 6% of oomycetes [69], highlighting the lack of research with biochar against pathogenic oomycetes. Interestingly, at the time only one oomycetes P. capsici was identified as soilborne with the rest foliar pathogens [69].
2.3 Biochar mechanisms of action against Fusarium and Phytophthora soilborne pathogens
Biochar can alter soil physicochemical properties such as soil pH, water holding capacity, bulk density, soil aggregation [35], which subsequently enhance the soil to suppress soilborne pathogens as shown in Figure 2 and Table 1. However, the effectiveness of biochar to alter any of these soil properties to suppress soilborne diseases depends on the application rate [24]. A major property of soil that leads to the control of soilborne pathogens is soil pH [14, 24, 79, 81, 82, 83, 84]. There have been several reports that showed that changes in soil pH can successfully control soilborne Fusarium wilt diseases [14, 24, 35, 81, 82, 83, 84]. Similarly, an oomycete soilborne pathogen such as Phytophthora has been reported to be suppressed by changes in soil pH, and this has also been reported for Phytophthora blight disease [79] including other Phytophthora soilborne pathogens. In vitro studies have shown that acidification suppresses the natural capacity of soil microbiome such as bacterial communities to fight pathogenic soilborne Fusarium infections because soil acidification disrupts the emission of antifungal substances [72]. The role of pH has been reported to transform soil via contributing atmospheric sulphur dioxide and nitrogen oxides because of the effect on bacterial populations in soil [85, 86]. Research has shown that sulphur compounds severely inhibits the growth of pathogenic fungi through the destruction of cell membranes or disruption of cellular antioxidation systems [86]. Under in vitro conditions, the optimal pH at which pathogen survived differed with among Phytophthora pathogens. For instance, an in vitro experiment showed that the optimum pH for P. citricola to survive was at 9, whereas P. tropicalis at pH 5, and five other species, P. citrophthora, P. insolita, P. irrigata, P. megasperma, and P. nicotianae, at pH 7 [87]. In another study, biochar was used to also suppress Phytophthora spp. in pineapple fields by amending soil with sulphur to lower pH from 6.3–5.1/5.4 [88]. Others have attributed the biochar induced inhibition of Phytophthora capsici to the augmented action of beneficial fungal microbial community of the soil [42]. Biochar induced resistance mechanisms were reported in Quercus rubra and Acer rubrum against P. cinnamomi, P. cactorum, respectively [78].
Figure 2.
Picture showing the effect of biochar on soilborne Fusarium and Phytophthora pathogens.
Pathogen class
Pathogen name
Host
Treatments (Biochar or supplemented with other agents)
Literature confirming Fusarium and Phytophthora soilborne pathogens treated with biochar as a stand-alone or supplemented with other disease control agents.
Nutrient availability is another indicator that regulates the dynamics of soilborne pathogen and plant health [79]. Biochar amendment is reported to contribute to soil nutrition through the release of available nutrients to the roots of plants which leads to the decrease in root hairs development [39], thereby reducing the surface area for root infection by soilborne pathogens [89]. A study showed that considerable amounts of P, K, and Ca with limited amount of Mg contributed to a reduction of soilborne pathogens such as Phytophthora [79] and Fusarium [90].
Biochar has variable amount of anti-oxidants, phenolics and other organic acids [91]. These compounds can be toxic at higher concentrations to activates plant defence systems [66, 92]. Biochar-borne organic stimuli showcase the potential to both activate both salicylic acid (SA) and jasmonic acid (JA), pathways [92, 93, 94]. Moreover, biochar can absorb toxins and accelerate the production of antibiotics together with influence on the chemical composition of root exudation, collectively inhibiting establishment of soilborne pathogens on plants. As a result of hermetic response of biochar borne chemicals, augmentation of resistance pathways has been extensively reported [66, 95].
The successful disease infection process by a pathogen relies on environmental factors (e.g., humidity, temperature, rainfall), susceptible host plant and the pathogen as depicted in the disease triangle [96]. This means that for biochar to successfully influence the soil physicochemical properties to suppress soilborne pathogens, it would need a favourable environmental and a mechanism to trigger some defences in the host plant against the pathogens. Although some studies have explored how biochar changes the dynamics of the soil physicochemical properties to suppress soilborne pathogens including Fusarium and Phytophthora, the effect of the environmental factors on applied biochar, and the mechanisms that could trigger defences in the host against soilborne pathogens remains a conundrum.
3. Limitations for biochar treatments against soilborne Fusarium and Phytophthora
The optimal dosage of biochar application is still not established because it depends on biochar type, soil types and target species. Earlier research elucidated that an application rate of biochar 0.5 to 135 t ha−1 supported positive plant growth responses [97]. Whereas, others have reported variable response of biochar type and application rate on the pathosystems [35]. Recent reports suggest inconsistent results for biochar tested at different concentrations against soilborne pathogens. For instance, Ralstonia solanacearum development in eggplants was suppressed at a lower concertation of 6% leaf waste biochar [98]. However, biochar of pinewood origin had more suppressive effective at a higher (20%) concentration against peach replant disease [99]. A deeper understanding of the mechanisms supporting biochar-mediated disease suppression is important for the development of products that can consistently reduce soilborne disease in the field [79]. Unfortunately to date, the scientific community lacks information for standardised biochar application rates and feedstock types used against soilborne Fusarium and Phytophthora. Acquiring data for biochar application rates, feedstock types and pyrolysis processes to support production of commercial biochar will massively transform the biochar and agriculture industries [60]. An approach for standardising biochar application rates will depend heavily on an established databank for biochar results showing specific application rates juxtaposed with the feedstock type, source, age, and whether biochar is made from standalone organic source or mixture. Information for soil type, and stage of soilborne Fusarium and Phytophthora pathogen treated will be relevant for adoption.
4. Prospects of biochar: Operationalising biochar for agricultural production systems
Although biochar is currently being advocated to be integrated into farming practices (Figure 3) as a soilborne disease or pathogen control tool, less is communicated about the most ideal application techniques. After testing the efficacy of biochar against soilborne diseases caused by Fusarium, Phytophthora, or other pathogens, the goal is to adopt and implement the findings to suit various farming systems. Current research has demonstrated that biochar is a promising soil amendment that controls soilborne Fusarium and Phytophthora pathogens [24, 25, 35, 43, 44, 67, 68, 69, 70, 78, 79, 84]. Majority of research confirming efficacy of biochar against Fusarium and Phytophthora soilborne pathogens have been experimented in potted plants under greenhouse or glasshouse conditions and this presents an opportunity for biochar application in nurseries where plant or crops are produced.
Figure 3.
Application of biochar in different agricultural production systems to manage soilborne Fusarium and Phytophthora.
Other nurseries that use bare-root production systems to produce planting materials may contribute to the spread of soilborne pathogens such as Fusarium and Phytophthora [100, 101, 102, 103]. Therefore, integrating biochar treatments into the nursery for plant production system as a disease control tool could serve as biosecurity tool to ensure clean healthy plant materials are supplied to farmers. This would limit the risk of introducing and spreading soilborne Fusarium or Phytophthora.
Greenhouse production systems could also benefit immensely from biochar as a soilborne disease control option. Vegetable crops such as tomato and pepper, which are also impacted by Fusarium and Phytophthora soilborne pathogens [25, 42, 79], are produced in both small- or large-scale commercial greenhouses. In colder countries such as Canada, the commercial greenhouse production systems are used for vegetable cultivation throughout the year. This is also true for other countries where farmlands are scarce. Treatment of soil or potting mix with biochar for vegetable production under greenhouse conditions could be integrated into the production practices to limit chemical treatments to manage pathogens such as Phytophthora capsici L. and F. oxysporum f.sp. lycopercisi for pepper and tomato respectively [24, 42, 79].
Although biochar has proved to be effective against soilborne pathogens Fusarium and Phytophthora, its large-scale application on farms may face economic challenges. More research is needed to explore the best biochar application methods for larger plantations where soils have been severely infested with Fusarium and Phytophthora pathogens. A comprehensive cost–benefit analysis is required for farmers operating on large farmlands who would want to explore the biochar treatments taking into consideration the direct and indirect cost in comparison with any existing Fusarium and Phytophthora soilborne disease management tools they are using.
Biochar as a soil amendment plays a crucial role in suppressing soilborne Fusarium and Phytophthora pathogens. However, there is still a significant knowledge gap regarding the application rates and extensive field trials for existing commercial biochar products from different feedstocks. It is imperative for more research to be conducted to establish appropriate application guidelines for farmers to make informed decisions prior to using biochar as soilborne diseases management tool. Although soil treatment with biochar could result in disease suppression, there is a risk that disease incidence could still exceed the economic threshold. Thus, attention should be given to biochar treatments that could suppress diseases from reaching this economic threshold. Further studies should be done to explore how environmental factors and plant host defence triggered mechanisms interact with biochar-treated soil against soilborne Fusarium and Phytophthora pathogens. Other aspects of biochar that must be explored includes potential confounding effects on humans and the environment to ensure that pros and cons are well understood. Most reported research on biochar efficacy against soilborne Fusarium and Phytophthora pathogens has been conducted under controlled conditions in pots. However, few studies have tested its effectiveness in the field. The lack of field trials makes it difficult to understand the effect biochar could have on Fusarium and Phytophthora soilborne pathogens in real field conditions. Another important reason why field trial is required to validate biochar efficacy is because of the heterogeneity nature of soil unlike potted soil. Research to develop biochar would be successful provided bioprocessing engineers, biochar technologists, and plant pathologists establish meaningful collaborations to explore the full potential of biochar for controlling soilborne diseases caused by Fusarium and Phytophthora pathogens. Involving policy advisors is also paramount to guide the adoption of biochar applications.
We appreciate the support of all the contributors of this review who committed their time to review material prior to submission. We also thank the editorial team that provided constructive feedback. We thank Prof. Hailong Wang at Foshan University, China and the Director of The Biochar Engineering Technology Research Centre of Guangdong Province for reviewing the manuscript and making constructive suggestions. We also thank Dr. Jiafa Lou for his constructive review.
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
References
1.Shafique HA, Sultana V, Ehteshamul-Haque S, Athar M. Management of soil-borne diseases of organic vegetables. Journal of Plant Protection Research. 2016;56:222-230
2.Mokhtar M, El-Mougy N. Bio-compost application for controlling soil-borne plant pathogens–a review. International Journal of Engineering and Innovative Technology. 2014;4:61-68
3.Bose T, Spies CF, Hammerbacher A, Coutinho TA. Phytophthora: An underestimated threat to agriculture, forestry, and natural ecosystems in sub-Saharan Africa. Mycological Progress. 2023;22:78
4.Hardy GSJ. Phytophthora root rot of Forest trees. In: Encyclopedia of Forest Sciences. Academic Press; 2004. pp. 758-766
5.Yan X, Guo S, Gao K, Sun S, Yin C, Tian Y. The impact of the soil survival of the pathogen of Fusarium wilt on soil nutrient cycling mediated by microorganisms. Microorganisms. 2023;11:2207
6.Dean R, Van Kan JA, Pretorius ZA, Hammond-Kosack KE, Di Pietro A, Spanu PD, et al. The top 10 fungalpathogens in molecular plant pathology. Molecular Plant Pathology. 2012;13:414-430
7.Jhariya MK, Banerjee A, Meena RS, Yadav DK. Agriculture, forestry and environmental sustainability: A way forward. In: Sustainable agriculture, forest and environmental management. Singapore: Springer; 2019. pp. 1-29
8.Bockus WW, Bowden RL, Hunger RM, Murray T, Smiley R. Compendium of Wheat Diseases and Pests. USA: American Phytopathological Society (APS Press); 2010
9.Hansen EM. Phytophthora species emerging as pathogens of forest trees. Current Forestry Reports. 2015;1:16-24
10.Dorrance AE. Management of Phytophthora sojae of soybean: A review and future perspectives. Canadian Journal of Plant Pathology. 2018;40:210-219
11.Adusei-Fosu K. Improving the Detection and Control of Fusarium Oxysporum f. Sp. Elaeidis. UK: University of Nottingham; 2017
12.Paugh KR, Gordon TR. Survival of Fusarium oxysporum f. sp. lactucae on crop residue in soil. Plant Disease. 2021;105:912-918
13.Scott J, McRoberts D, Gordon T. Colonization of lettuce cultivars and rotation crops by Fusarium oxysporum f. sp. lactucae, the cause of Fusarium wilt of lettuce. Plant Pathology. 2014;63:548-553
14.McDonald MR, Collins B, duToit L, Adusei-Fosu K. Soil amendments and fumigation for the management of Fusarium wilt of bunching spinach in Ontario, Canada. Crop Protection. 2021;145:105646
15.Parajuli M, Baysal-Gurel F. Control of Phytophthora and Rhizoctonia root rot on red maple using fungicides and biofungicides. HortScience. 2022;57:1306-1312
16.Foster J, Hausbeck M. Managing Phytophthora crown and root rot in bell pepper using fungicides and host resistance. Plant Disease. 2010;94:697-702
17.Amini J, Sidovich D. The effects of fungicides on Fusarium oxysporum f. sp. lycopersici associated with Fusarium wilt of tomato. Journal of Plant Protection Research. 2010;50:172-178
18.Hu C-H, Perez FG, Donahoo R, McLeod A, Myers K, Ivors K, et al. Recent genotypes of Phytophthora infestans in the eastern United States reveal clonal populations and reappearance of mefenoxam sensitivity. Plant Disease. 2012;96:1323-1330
19.Patel JS, Vitoreli A, Palmateer AJ, El-Sayed A, Norman DJ, Goss EM, et al. Characterization of Phytophthora spp. isolated from ornamental plants in Florida. Plant Disease. 2016;100:500-509
21.Das MM, Haridas M, Sabu A. Biological control of black pepper and ginger pathogens, Fusarium oxysporum, Rhizoctonia solani and Phytophthora capsici, using Trichoderma spp. Biocatalysis and Agricultural Biotechnology. 2019;17:177-183
22.Larkin RP, Fravel DR. Efficacy of various fungal and bacterial biocontrol organisms for control of Fusarium wilt of tomato. Plant Disease. 1998;82:1022-1028
23.Alabouvette C, Olivain C, Migheli Q, Steinberg C. Microbiological control of soil-borne phytopathogenic fungi with special emphasis on wilt-inducing Fusarium oxysporum. The New Phytologist. 2009;184:529-544
24.Jin X, Zhou X, Wu F, Xiang W, Pan K. Biochar amendment suppressed Fusarium wilt and altered the rhizosphere microbial composition of tomatoes. Agronomy. 2023;13:1811
25.Akhter A, Hage-Ahmed K, Soja G, Steinkellner S. Potential of Fusarium wilt-inducing chlamydospores, in vitro behaviour in root exudates and physiology of tomato in biochar and compost amended soil. Plant and Soil. 2016;406:425-440
26.Saravanan A, Kumar PS. Biochar derived carbonaceous material for various environmental applications: Systematic review. Environmental Research. 2022;214:113857
27.Wu P, Wang Z, Bolan NS, Wang H, Wang Y, Chen W. Visualizing the development trend and research frontiers of biochar in 2020: A scientometric perspective. Biochar. 2021;3:419-436
28.Yadav SPS, Bhandari S, Bhatta D, Poudel A, Bhattarai S, Yadav P, et al. Biochar application: A sustainable approach to improve soil health. Journal of Agriculture and Food Research. 2023;11:100498
29.Gao Y, Chen H, Fang Z, Niazi NK, Adusei-Fosu K, Li J, et al. Coupled sorptive and oxidative antimony(III) removal by iron-modified biochar: Mechanisms of electron-donating capacity and reactive Fe species. Environmental Pollution. 2023;337:122637
30.Hussain MM, Bibi I, Ali F, Saqib ZA, Shahid M, Niazi NK, et al. The role of various ameliorants on geochemical arsenic distribution and CO2-carbon efflux under paddy soil conditions. Environmental Geochemistry and Health. 2023;45:507-523
31.Liu J, Wei X, Ren S, Qi J, Cao J, Wang J, et al. Synergetic removal of thallium and antimony from wastewater with jacobsite-biochar-persulfate system. Environmental Pollution. 2022;304:119196
32.Luo J, Li X, Ge C, Müller K, Yu H, Deng H, et al. Preparation of ammonium-modified cassava waste-derived biochar and its evaluation for synergistic adsorption of ternary antibiotics from aqueous solution. Journal of Environmental Management. 2021;298:113530
33.Niazi NK, Bibi I, Shahid M, Ok YS, Shaheen SM, Rinklebe J, et al. Arsenic removal by Japanese oak wood biochar in aqueous solutions and well water: Investigating arsenic fate using integrated spectroscopic and microscopic techniques. Science of the Total Environment. 2018;621:1642-1651
34.Pan H, Yang X, Chen H, Sarkar B, Bolan N, Shaheen SM, et al. Pristine and iron-engineered animal-and plant-derived biochars enhanced bacterial abundance and immobilized arsenic and lead in a contaminated soil. Science of the Total Environment. 2021;763:144218
35.Poveda J, Martínez-Gómez Á, Fenoll C, Escobar C. The use of biochar for plant pathogen control. Phytopathology. 2021;111:1490-1499
36.Kammann C, Ratering S, Eckhard C, Müller C. Biochar and hydrochar effects on greenhouse gas (carbon dioxide, nitrous oxide, and methane) fluxes from soils. Journal of Environmental Quality. 2012;41:1052-1066
37.Laird DA, Fleming P, Davis DD, Horton R, Wang B, Karlen DL. Impact of biochar amendments on the quality of a typical Midwestern agricultural soil. Geoderma. 2010;158:443-449
38.Lehmann J, Rillig M, Thies J, Masiello CA, Hockaday WC, Crowley D. Biochar effects on soil biota: A review. Soil Biology and Biochemistry. 2011;43:1812-1836
39.Prendergast-Miller MT, Duvall M, Sohi SP. Biochar-root interactions are mediated by biochar nutrient content and impacts on soil nutrient availability. European Journal of Soil Science. 2014;65:173-185
40.Zhang M, Riaz M, Zhang L, El-Desouki Z, Jiang C. Biochar induces changes to basic soil properties and bacterial communities of different soils to varying degrees at 25 mm rainfall: More effective on acidic soils. Frontiers in Microbiology. 2019;10:1321
41.Ahluwalia O, Singh P, Bhatia R. A review on drought stress in plants: Implications, mitigation and the role of plant growth promoting rhizobacteria. Resources, Environment and Sustainability. 2021;5:100032
42.Wang G, Ma Y, Chenia HY, Govinden R, Luo J, Ren G. Biochar-mediated control of Phytophthora blight of pepper is closely related to the improvement of the rhizosphere fungal community. Frontiers in Microbiology. 2020;11:1427
43.Elmer W. Effect of leaf mold mulch, biochar, and earthworms on mycorrhizal colonization and yield of asparagus affected by Fusarium crown and root rot. Plant Disease. 2016;100:2507-2512
44.Elmer WH, Pignatello JJ. Effect of biochar amendments on mycorrhizal associations and Fusarium crown and root rot of asparagus in replant soils. Plant Disease. 2011;95:960-966
46.Mishra RK, Mohanty K. A review of the next-generation biochar production from waste biomass for material applications. Science of the Total Environment. 2023;904:167171
47.Weber K, Quicker P. Properties of biochar. Fuel. 2018;217:240-261
48.Mukherjee A, Zimmerman AR. Organic carbon and nutrient release from a range of laboratory-produced biochars and biochar–soil mixtures. Geoderma. 2013;193:122-130
49.Li H, Tan Z. Preparation of high water-retaining biochar and its mechanism of alleviating drought stress in the soil and plant system. Biochar. 2021;3:579-590
50.Rafiq MK, Bachmann RT, Rafiq MT, Shang Z, Joseph S, Long R. Influence of pyrolysis temperature on physico-chemical properties of corn stover (Zea mays L.) biochar and feasibility for carbon capture and energy balance. PLoS One. 2016;11:e0156894
51.Tomczyk A, Sokołowska Z, Boguta P. Biochar physicochemical properties: Pyrolysis temperature and feedstock kind effects. Reviews in Environmental Science and Bio/Technology. 2020;19:191-215
52.Enders A, Hanley K, Whitman T, Joseph S, Lehmann J. Characterization of biochars to evaluate recalcitrance and agronomic performance. Bioresource Technology. 2012;114:644-653
53.Jindo K, Mizumoto H, Sawada Y, Sanchez-Monedero MA, Sonoki T. Physical and chemical characterization of biochars derived from different agricultural residues. Biogeosciences. 2014;11:6613-6621
54.Singh B, Singh BP, Cowie AL. Characterisation and evaluation of biochars for their application as a soil amendment. Soil Research. 2010;48:516-525
55.Lei O, Zhang R. Effects of biochars derived from different feedstocks and pyrolysis temperatures on soil physical and hydraulic properties. Journal of Soils and Sediments. 2013;13:1561-1572
56.Asadi H, Ghorbani M, Rezaei-Rashti M, Abrishamkesh S, Amirahmadi E, Chengrong C, et al. Application of rice husk biochar for achieving sustainable agriculture and environment. Rice Science. 2021;28:325-343
57.Domingues RR, Trugilho PF, Silva CA, ICND M, Melo LC, Magriotis ZM, et al. Properties of biochar derived from wood and high-nutrient biomasses with the aim of agronomic and environmental benefits. PLoS One. 2017;12:e0176884
58.Duku MH, Gu S, Hagan EB. A comprehensive review of biomass resources and biofuels potential in Ghana. Renewable and Sustainable Energy Reviews. 2011;15:404-415
59.Ghorbani M, Neugschwandtner RW, Konvalina P, Asadi H, Kopecký M, Amirahmadi E. Comparative effects of biochar and compost applications on water holding capacity and crop yield of rice under evaporation stress: A two-years field study. Paddy and Water Environment. 2023;21:47-58
60.Liu Z, Jia M, Li Q, Lu S, Zhou D, Feng L, et al. Comparative analysis of the properties of biochars produced from different pecan feedstocks and pyrolysis temperatures. Industrial Crops and Products. 2023;197:116638
61.Nwajiaku IM, Olanrewaju JS, Sato K, Tokunari T, Kitano S, Masunaga T. Change in nutrient composition of biochar from rice husk and sugarcane bagasse at varying pyrolytic temperatures. International Journal of Recycling of Organic Waste in Agriculture. 2018;7:269-276
62.Li S, Harris S, Anandhi A, Chen G. Predicting biochar properties and functions based on feedstock and pyrolysis temperature: A review and data syntheses. Journal of Cleaner Production. 2019;215:890-902
63.Suga H, Hyakumachi M. Genomics of phytopathogenic Fusarium. In: Applied Mycology and Biotechnology. Volume 4: Fungal Genomics. Netherlands: Elsevier Science B.V.; 2004. pp. 161-189
64.Rossman AY, Palm ME. Why are Phytophthora and other Oomycota not true fungi? Outlooks on Pest Management. 2006;17:217
65.Nehra S, Gothwal RK, Varshney AK, Solanki PS, Chandra S, Meena P, et al. Chapter 19 - bio-management of Fusarium spp. associated with fruit crops. In: Sharma VK, Shah MP, Parmar S, Kumar A, editors. Fungi Bio-Prospects in Sustainable Agriculture, Environment and Nano-Technology. Academic Press; 2021. pp. 475-505. Available from: https://shop.elsevier.com/books/fungi-bio-prospects-in-sustainable-agriculture-environment-and-nano-technology/sharma/978-0-12-821734-4
66.Akhter A, Hage-Ahmed K, Soja G, Steinkellner S. Compost and biochar alter mycorrhization, tomato root exudation, and development of Fusarium oxysporum f. sp. lycopersici. Frontiers in Plant Science. 2015;6:529
67.Eo J, Park K-C, Kim M-H, Kwon S-I, Song Y-J. Effects of rice husk and rice husk biochar on root rot disease of ginseng (Panax ginseng) and on soil organisms. Biological Agriculture & Horticulture. 2018;34:27-39
68.Wang Q, Fang W, Yan D, Han D, Li Y, Ouyang C, et al. The effects of biochar amendment on dimethyl disulfide emission and efficacy against soil-borne pests. Water, Air, & Soil Pollution. 2016;227:1-9
69.Iacomino G, Idbella M, Laudonia S, Vinale F, Bonanomi G. The suppressive effects of biochar on above- and belowground plant pathogens and pests: A review. Plants. 2022;11:3144
70.Akanmu A, Sobowale A, Abiala M, Olawuyi O, Odebode A. Efficacy of biochar in the management of Fusarium verticillioides Sacc. causing ear rot in Zea mays L. Biotechnology Reports. 2020;26:e00474
71.Asif M, Haider MS, Akhter A. Impact of biochar on Fusarium wilt of cotton and the dynamics of soil microbial community. Sustainability. 2023;15:12936
72.Liu Z, Zhou W, Sun Y, Peng Y, Niu J, Tan J, et al. Biochar and its coupling with microbial inoculants for suppressing plant diseases: A review. Applied Soil Ecology. 2023;190:105025
73.Judelson HS, Blanco FA. The spores of Phytophthora: Weapons of the plant destroyer. Nature Reviews Microbiology. 2005;3:47-58
74.Thines M. Oomycetes. Current Biology. 2018;28:R812-R813
76.Gadgil PD. Phytophthora Heveae, a Pathogen of Kauri. New Zealand: New Zealand Forest Service; 1974
77.Volynchikova E, Kim KD. Biological control of oomycete Soilborne diseases caused by Phytophthora capsici, Phytophthora infestans, and Phytophthora nicotianae in Solanaceous crops. Mycobiology. 2022;50:269-293
78.Zwart DC, Kim SH. Biochar amendment increases resistance to stem lesions caused by Phytophthora spp. in tree seedlings. HortScience. 2012;47:1736-1740
79.Shoaf N, Hoagland L, Egel DS. Suppression of Phytophthora blight in sweet pepper depends on biochar amendment and soil type. HortScience. 2016;51:518-524
80.Postma J, Clematis F, Nijhuis EH, Someus E. Efficacy of four phosphate-mobilizing bacteria applied with an animal bone charcoal formulation in controlling Pythium aphanidermatum and Fusarium oxysporum f.sp. radicis lycopersici in tomato. Biological Control. 2013;67:284-291
81.Cruz DR, Leandro LFS, Munkvold GP. Effects of temperature and pH on Fusarium oxysporum and soybean seedling disease. Plant Disease. 2019;103:3234-3243
82.Jayaraman S, Naorem AK, Lal R, Dalal RC, Sinha NK, Patra AK, et al. Disease-suppressive soils-beyond food production: A critical review. Journal of Soil Science and Plant Nutrition. 2021;21:1437-1465
83.Orr R, Nelson PN. Impacts of soil abiotic attributes on Fusarium wilt, focusing on bananas. Applied Soil Ecology. 2018;132:20-33
84.Segura RA, Stoorvogel JJ, Sandoval JA. The effect of soil properties on the relation between soil management and Fusarium wilt expression in Gros Michel bananas. Plant and Soil. 2022;471:89-100
85.Mahala DM, Maheshwari HS, Yadav RK, Prabina BJ, Bharti A, Reddy KK, et al. Microbial transformation of nutrients in soil: An overview. In: Rhizosphere Microbes: Soil and Plant Functions. Singapore: Springer Nature; 2020. pp. 175-211
86.Xie P, Li C-L, Shao B, Xu X-J, Chen X-D, Zhao L, et al. Simultaneous removal of carbon dioxide, sulfur dioxide and nitric oxide in a biofilter system: Optimization operating conditions, removal efficiency and bacterial community. Chemosphere. 2021;276:130084
87.Naqvi S. Phytophthora diseases of citrus and management strategies. Annual Review of Plant Pathology (India: Scientific Publishers). 2003;2:239-270
88.Loekito S, Afandi, Afandi A, Nishimura N, Koyama H, Senge M. Study on Soil Properties and Species Conformity of Phytophthora Species in a Pineapple Field. Pakistan: CABI; 2022
89.Graber ER, Frenkel O, Jaiswal AK, Elad Y. How may biochar influence severity of disease caused by soilborne pathogens? Carbon Management. 2015;5:169-183
90.Höper HC, Steinberg C, Alabouvette C. Involvement of clay type and pH in the mechanisms of soil suppressiveness to Fusarium wilt of flax. Soil Biology and Biochemistry. 1995;27:955-967
91.Graber ER, Harel YM, Kolton M, Cytryn E, Silber A, David DR, et al. Biochar impact on development and productivity of pepper and tomato grown in fertigated soilless media. Plant and Soil. 2010;337:481-496
92.Elad Y, David DR, Harel YM, Borenshtein M, Kalifa HB, Silber A, et al. Induction of systemic resistance in plants by biochar, a soil-applied carbon sequestering agent. Phytopathology. 2010;100:913-921
93.Harel YM, Elad Y, Rav-David D, Borenstein M, Shulchani R, Lew B, et al. Biochar mediates systemic response of strawberry to foliar fungal pathogens. Plant and Soil. 2012;357:245-257
94.Mehari ZH, Elad Y, Rav-David D, Graber ER, Harel YM. Induced systemic resistance in tomato (Solanum lycopersicum) against Botrytis cinerea by biochar amendment involves jasmonic acid signaling. Plant and Soil. 2015;395:31-44
95.Graber ER, Elad Y. Biochar impact on plant resistance to disease. In: Ladygina N, Rineau F, editors. Biochar and Soil Biota. Boca Raton, FL: CRC Press; 2013. pp. 41-68
96.Agrios G. Plant Pathology 5th Edition. Burlington, Ma. USA: Elsevier academic press; 2005. pp. 79-103
97.Glaser B, Lehmann J, Zech W. Ameliorating physical and chemical properties of highly weathered soils in the tropics with charcoal–a review. Biology and Fertility of Soils. 2002;35:219-230
98.Ahmad CA, Akhter A, Haider MS, Abbas MT, Hashem A, Avila-Quezada GD, et al. Demonstration of the synergistic effect of biochar and Trichoderma harzianum on the development of Ralstonia solanacearum in eggplant. Frontiers in Microbiology. 2024;15:1360703
99.Atucha A, Litus G. Effect of biochar amendments on peach replant disease. HortScience. 2015;50:863-868
100.Cobb RC, Haas SE, Kruskamp N, Dillon WW, Swiecki TJ, Rizzo DM, et al. The magnitude of regional-scale tree mortality caused by the invasive pathogen Phytophthora ramorum. Earth's Future. 2020;8:e2020EF001500
101.Donald F, Purse BV, Green S. Investigating the role of restoration plantings in introducing disease—A case study using Phytophthora. Forests. 2021;12:764
102.Green S, Cooke DE, Dunn M, Barwell L, Purse B, Chapman DS, et al. Phyto-threats: Addressing threats to UK forests and woodlands from Phytophthora. Forests. 2021;12(12):1617
103.Wingfield M, Hammerbacher A, Ganley R, Steenkamp E, Gordon T, Wingfield B, et al. Pitch canker caused by Fusarium circinatum—A growing threat to pine plantations and forests worldwide. Australasian Plant Pathology. 2008;37:319-334
Written By
Kwasi Adusei-Fosu, Goldy De Bhowmick, Adnan Akhter and Muhammad Taqqi Abbas
Submitted: 01 May 2025Reviewed: 21 May 2025Published: 25 August 2025
Open access peer-reviewed chapter - ONLINE FIRST
