Control Of Root Rot Research Articles

Identification and characterization of biocontrol agent Lysinibacillus boronitolerans P42 against Cerrena unicolor that causes root rot of arecanut palm

The arecanut palm is one of the most important industrial crops in tropical area around the world. The root rot of arecanut palm, which is caused by Cerrena unicolor, has led to heavy economic losses and restricted greatly the development of arecanut industry, especially in Hainan province of China. The common use of chemical agents has worsened the problems of the emergence of resistant pathogens and the pollution of agricultural environment. This study aims to screen and identify a more effective and environment friendly biocontrol method for the prevention and treatment of root rot of arecanut palm. The mycelium growth rate is investigated to select antagonistic bacteria from tropical crop rotation fields which show improved resistance against soil-borne pathogens, and the strain P42 is revealed with the strongest antagonistic effects (82.18%). Based on 16s rDNA sequence analysis, the strain P42 is identified as Lysinibacillus boronitolerans. In vitro antimicrobial activity shows that the strain P42 exhibits broad-spectrum antagonistic activity against a wide variety of tropical agricultural fungal pathogens, including Cerrena unicolor, Magnaporthe oryzea, Botryodiplodia theobromae, Neoscytalidium dimidiatum, Thanatephorus cucumeris, Fusarium oxysporum, and Botrytis cinereaPer.. The antagonistic activity of the culture of P42 is tolerant to common proteases, longer storage time, and temperature range of 40-121°C; and is significantly influenced by alkaline (7-9) and acidic (1-2) pH, as well as by ultraviolet ray treatment for more than 30min. The investigation on the antagonistic activity of the crude extract of fermentation filtrate indicates that the active compounds might be lipopeptides, polyketones, or proteins. To our knowledge, this is the first report of L. boronitolerans as potential bio-reagents for controlling root rot of arecanut palm caused by Cerrena unicolor.

Bacillus amyloliquefaciens FG14 as a potential biocontrol strain against rusty root rot of Panax ginseng, and its impact on the rhizosphere microbial community

Rusty root rot is the most destructive disease in ginseng production. The bacterial strain FG14 isolated from the rhizosphere of Panax ginseng was characterised as Bacillus amyloliquefaciens. The inhibition rates of the FG14 bacterial suspension against the mycelial growth, spore production and spore germination of Ilyonectria robusta which causes ginseng rusty root rot were all more than 90% at a concentration of 108 cfu/mL. The sterile fermentation broth of strain FG14 also had significant inhibitory ability. The results of plantgrowth promotion showed that the fresh weight and root length of ginseng seedlings treated with 3 × 108 cfu/mL FG14 bacterial suspension were 4.49 times and 2.12 times greater than the seedlings treated with I. robusta. The soil enzyme activities of urease, phosphatase, invertase, and catalase of strain FG14 and the expression of seven lipopeptide biosynthesis genes were up-regulated, and antifungal metabolite production was stable. The diversity and abundance of bacterial and fungal communities in rhizosphere soil changed during different growth stages of ginseng after inoculation with strain FG14. The relative abundance of the Ilyonectria genus was significantly lower than the water control at the leaf spreading stage of P. ginseng. These results indicate the great potential of B. amyloliquefaciens FG14 for use as a biological agent for the green control of ginseng rusty root rot.

Fungal and bacterial endophytes antagonistic to Phytophthora species causing root rot in Cinnamomum cassia

Endophytes were investigated for their potential to protect Cinnamomum cassia (cinnamon) from Phytophthora root rot. From healthy cinnamon trees in diseased plantations, 134 bacterial and fungal endophytes were isolated and screened in vitro for their ability to antagonise the root rot pathogens Phytophthora cinnamomi, P. multibullata and P. × vanyenensis. Seventeen endophytes exhibiting high levels of antagonism in vitro (more than 45%) were then tested in a glasshouse study for their ability to reduce the impact of Phytophthora infection in cinnamon seedlings. Trials using cinnamon seeds or seedlings inoculated with an endophyte and then infested with Phytophthora identified three endophytes expressing high levels of disease suppression (based on root damage reduction) and plant growth promotion. These were Penicillium citrinum, Xylaria curta and Clonostachys rosea. These endophytes can potentially be used in the biological control of root rot in cinnamon, but this must be explored further under field conditions.

Arbuscular mycorrhizal fungi as a promising biomaterial for controlling root rot of Panax notoginseng

Root rot is a main disease in Panax notoginseng, which is severe and difficult to control. Arbuscular mycorrhizal fungi (AMF) are known to effectively prevent plant diseases caused by soil-borne pathogens. However, the potential role of AMF as a biocontrol agent against root rot in P. notoginseng is still unclear. This study aims to investigate the efficacy of AMF, including Funneliformis mosseae, Rhizophagus intraradices and Claroideoglomus etunicatum, individually and in combination, for controlling root rot in P. notoginseng seedlings. The effect of different AMF on the indicators of P. notoginseng growth, superoxide dismutase, peroxidase activity, proline, malondialdehyde, soluble sugars and proteins were measured. The effects of different AMF on root rot resistance were comprehensively evaluated using the subordinate function method. The results showed that the incidence of root rot decreased from 75% to 12.5%–50.0% after inoculation with different AMF agents, and the disease index decreased from 22.92% to 6.25%–16.67%. Moreover, AMF significantly increased the growth parameters of P. notoginseng, such as plant height (6.35%–41.73%), stem diameter (12.98%–45.96%), fresh weight (6.28%–95.35%), and leaf area (8.89%–97.71%). Moreover, AMF also improved the content of chlorophyll (2.40%–50.67%) and rate of net photosynthetic (52.08%– 279.17%), enhancing superoxide dismutase (4.02%–114.89%) and peroxidase activity (85.60%–139.98%), as well as promoting the accumulation of soluble sugars (30.21%–90.00%), proteins (3.31%–65.81%), and proline (4.02%–114.89%) in the root and leaf, while reducing the malondialdehyde content (19.99%–139.98%). Particularly, C. etunicatum was found to be the most effective in promoting growth and disease resistance in P. notoginseng. These findings provide insights into the potential use of AMF as an effective biocontrol agent to manage root rot.

Trichoderma harzianum as a potential biological agent in control of the charcoal root rot of sugar beet

Trichoderma harzianum as a potential biological agent in control of the charcoal root rot of sugar beet

Activity of Essential Oils and Plant Extracts as Biofungicides for Suppression of Soil-Borne Fungi Associated with Root Rot and Wilt of Marigold (Calendula officinalis L.)

Essential oils (EOs) and Plant extracts (PEs) are gaining attention as eco-friendly alternatives to synthetic fungicides for the management of soil-borne fungi related to root rot and the wilt of marigolds. Here, EOs of Cinnamomum zeylanicum (cinnamon), Mentha piperita (peppermint), Syzygium aromaticum (clove), Thymus vulgaris (thyme), PEs of Cymbopogon citratus (lemongrass), Lantana camara (lantana), Ocimum basilicum (basil), and Zingiber officinales (ginger) were first evaluated in vitro for their inhibitory activity against the mycelium growth of the root rot and wilt fungi of marigold: Rhizoctonia solani, Sclerotinia sclerotiorum, Fusarium oxysporum, and F. solani, and in vivo for their activity in reducing disease progression. The results show that all EOs had a strong inhibitory activity on the mycelium growth of pathogens. Maximum inhibition of mycelium growth was achieved at a concentration of 1 mL/Lof S. aromaticum, C. zeylanicum, and M. piperita. The inhibition values were 100, 80.9, and 72.4% for F. solani, 100, 81.1, and 70% for S. sclerotiorum, 90.2, 79.4, and 69.1% for F. oxysporum, and 85.4, 78.2, and 68.7% for R. solani, respectively. Regarding plant extracts, the highest inhibition of mycelium growth was attained at a concentration of 20% of Z. officinales, C. citratus, and L. camara. The inhibition values were 77.4, 69.1, and 60.6% for F. solani, 76.5, 67.2, and 58% for S. sclerotiorum, 73.5, 68.2, and 56.3% for F. oxysporum, and 72, 64.8, and 55.2% for R. solani, respectively. In pot experiments, the application of EOs and PEs showed high efficiency in suppressing root rot and wilt of marigold at all concentrations used, especially at 3 mL/L for seed soaking (along with 1.5 mL/L for foliar spraying) for S. aromaticum, C. zeylanicum, and M. piperita EOs, and (40% for seed soaking along with 20% for foliar spraying) for Z. officinales, C. citratus, and L. camara PEs. All the treatments applied in the field greatly reduced the diseases in both seasons, especially S. aromaticum EO, C. zeylanicum EO, Z. officinales PE, and carbendazim treatments. This was accompanied by a significant improvement in morphological, yield, and phytochemical parameters of marigold as well as a significant increase in the activity of defense-related antioxidant enzymes. Overall, essential oils and plant extracts can be used effectively to control root rot and wilt in marigold as sustainable and eco-friendly botanical biofungicides.

Molecular mechanisms of Phytophthora sojae avirulence effectors escaping host recognition.

Phytophthora sojae is a well-known destructive oomycete pathogen, which causes soybean stem and root rot and poses a serious threat to global food security. Growing soybean cultivars with the appropriate resistance to P. sojae (Rps) genes are the primary management strategy to reduce losses. In most Phytophthora pathosystems, host resistance protein encoded by a specific R gene in the plant recognizes corresponding RxLR effector protein, encoded by an avirulence gene. This gene-for-gene relationship has been exploited to help breeders and agronomists deploy soybean cultivars. To date, 6 Rps genes have been incorporated into commercial soybean germplasm and trigger plant immunity in response to 8 P. sojae avirulence effectors. The incorporation of Rps genes in the soybean population creates selection pressure in favor of novel pathotypes of P. sojae. The 8 avirulence genes evolved to evade the host immune system, driven by genetic selection pressures. Understanding the evading strategies has important reference value for the prevention and control of Phytophthora stem and root rot. This investigation primarily highlights the research on the strategies of P. sojae avirulence effector evasion of host recognition, looking forward to creating durable resistance genes and thereby enabling successful disease management.

Cell-free culture filtrate of Trichoderma longibrachiatum AD-1 as alternative approach to control Fusarium solani and induce defense response Phaseolus vulgaris L. plants

The present study was conducted to evaluate the antifungal activities of cell-free culture filtrate of Trichoderma isolated from rhizospheric soil of common bean (Phaseolus vulgaris L.) plants against growth and spore germination of Fusarium solani. The results noted that the cell-free culture filtrate of Trichoderma at different concentrations of isolated Trichoderma longibrachiatum AD-1 significantly inhibited mycelial growth of F. solani with growth reduction ranging from 28.8 to 97.3% and inhibited spore germination up to 96%. Compared to control, soil treated with cell-free culture filtrate of T. longibrachiatum AD-1 exhibited a significant reduction in the frequency of root rot disease and boosted the percentage of surviving plants and vegetative growth. To get insight into the biocontrol mechanism, we employed Real-Time Quantitative Reverse Transcription PCR (RT-qPCR), which revealed that the cell-free culture filtrate of Trichoderma in common bean (Phaseolus vulgaris L.) showed significant upregulation of defense-related genes PR1, PR2, PR3, and PR4. This study revealed that the cell-free culture filtrate of Trichoderma could be promising to develop an alternative natural agent to control root rot diseases caused by Fusarium spp.

Combined Application of Trichoderma harzianum and Paclobutrazol to Control Root Rot Disease Caused by Rhizoctonia solani of Tomato Seedlings

Many root diseases can cause serious damage to tomato (Solanum lycopersicum L.) production during the seedling growth period, particularly Rhizoctonia solani, Pythium spp., and Alternaria spp. Paclobutrazol (PBZ) has proved to reduce the damage of the Alternaria blight disease on tomato seedlings. The present investigation was designated to evaluate the growth of infected tomato seedlings with R. solani under applications of Trichoderma harzianum alone, PBZ alone, both PBZ and T. harzianum, and comparing with applied fungicide. PBZ enhanced the chlorophyll system in tomato seedlings, enzymatic antioxidants, and the total antioxidants, besides the vegetative parameters. The combined application of both PBZ and Trichoderma significantly improved growth parameters, decreased the damping off percent of R. solani, as well as increased the enzymatic antioxidants and the total antioxidants of tomato seedlings. It was found that applying 100 mg L−1 PBZ did not affect the effectiveness of the biocontrol agent of T. harzianum. The images of the scanning electron microscope (SEM) confirm that PBZ showed twisting, shrinking, and collapsing of lysis and hyphae in cultures of R. solani. This is the first report that confirms the biochemical control of R. solani on tomato seedlings using the combined application of PBZ and T. harzianum. Further studies are still needed to test more Trichoderma species and different phytopathogens.

Evaluating the Impact of Trichoderma brevicompactum 31636 on Root Rot of Atractylodes macrocephala and the Fungal Community in the Rhizosphere Soil

Trichoderma brevicompactum can control of plant diseases, but there are few studies about the control of root rot by T. brevicompactum 31636 and its biocontrol mechanism. To explore the impact of T. brevicompactum 31636 on root rot and the structure of fungal communities of rhizosphere soil. The effect of T. brevicompactum 31636 on controlling root rot was assessed, the growth of plants was observed by pot experiments, and the fungal structure was detected by high-throughput sequencing analysis. Compared with the CK (healthy plants) group, the plant height, fresh weight, and dry weight increased by 55.3%, 48.55% and 57.8%, respectively. While the concentration of atractylenolide I, II, III, and atractylone increased by 19.35%, 16.96%, 89.42% and 89.32%, respectively. The results of pot experiments indicated that T. brevicompactum 31636 could significantly improve the survival rate of Atractylodes macrocephala . The results of principal coordinates analysis (PCoA) showed that the sample of CK and Fo+Th (adding Fusdrium oxysporum before T. brevicompactum 31636) group on one side, and samples of Th and Fo group on the other. Furthermore, among the top 20 dominant fungi detected, the fungal genus with 1% increase of relative abundance included Trichoderma (1%), Sordariomycetes (1.5%), Mortierella (1.3%), Penicillium (1%), meanwhile the fungal genus with 1% decrease of relative abundance included Fusarium (30%) and Pleosporales (1%). In summary, T. brevicompactum 31636 can control the root rot of A. macrocephala by regulating of the soil fungal community and inhibiting pathogen.

EVALUATION OF NATIVE ANTAGONISTS FOR THE MANAGEMENT OF STEM ROTS OF CLUSTER BEAN CAUSED BY SCLEROTIUM ROLFSII SACC.

Cluster bean, Cyamopsis tetragonoloba (L.) Taub is an important annual legume crop of kharif season in arid and semi-arid regions of the Indian subcontinent. Six fungal antagonists and four bacterial antagonists were evaluated against Sclerotium rolfsii in vitro and in vivo condition to develop an effective management strategy for stem rot of cluster bean. During in vitro studies, native fungal and bacterial antagonists were inhibited the mycelial growth of pathogen. Among the fungal antagonists tested, the isolate-I4 (THM) showed the maximum growth inhibition of S. rolfsii up to 68.10 per cent. The bacterial antagonist Isolate-I3 (PFV) recorded the maximum inhibition zone of 13.33 mm and a minimum of 23.00 mm mycelial growth of S. rolfsii. Pot culture studies revealed that the combined application of T9-T. harzianum (THM) + P. fluorescens (PFV) (ST+ SA) through seed treatment and soil application recorded the minimum incidence of stem rot (4.66 per cent) and maximum plant height, number of pods/plant and pod length.The findings reported in the present study supported the applicability of isolate-I4 (THM) Isolate-I3 (PFV) as a possible alternative to fungicides for the control of root rot in black gram.

Research Progress in Detection and Control of Soil Borne Disease Fusarium Root Rot

Fusarium is a variety of species, which is difficult to distinguish in morphology. Traditionally, identification of pathogenic fusarium requires the separation of pathogenic bacteria, purification of pathogenic bacteria, separation and purification after tieback, sequencing and other processes, which are time-consuming and laborious. Molecular detection technology can make pathogen identification more efficient. Fusarium control mainly includes cultivating disease-resistant varieties, chemical control, physical control, biological control and crop rotation. In recent years, various root rot bacteria caused by Fusarium have shown an increasing trend. By reviewing the previous relevant research results, this study summarized the research progress of molecular detection and prevention measures of root rot caused by the soilborne disease fungus Fusarium, and explored the current research status and existing problems of fusarium. In order to provide theoretical reference for further study of soil-borne pathogenic fungi.

Sustainable production of biopesticides for common bean root rot control within the biorefinery approach: a Technology Readiness Level 3 experimental proof of concept.

Biopesticides are recognized as an efficient alternative to synthetic pesticides for pest and disease crop management. However, their commercial production processes use grains, generating large amounts of organic waste, even when agriculture waste or byproducts are the feedstock of choice. Frequently, these organic wastes are rich in nutrients that, after adequate treatment, can be used as nitrogen and carbohydrate sources for secondary metabolite production produced by microorganisms during submerged fermentation. In this sense, this study aimed to prove the concept that biopesticides could be produced under a full biorefinery process, using the entire biomass of an underexplored agroindustrial waste-damaged bean-as the main feedstock. A combination of sequential processes, including solid state fermentation, hydrolysis, and submerged fermentation, were designed for the production of two biopesticides (conventional-fungal conidia and second-generation secondary metabolite-cerulenin) from a high potential biological control agent strain Sarocladium oryzae BRM 59907. The combined processes, using damaged common bean grain as the main feedstock, provided biopesticides and organic fertilizer production that successfully controlled common bean root rot disease. This work proved to be possible the biopesticide production using a full biorefinery concept, inside the same productive chain, contributing to a sustainable environment and economy, together with animal and human health safety.

The potential of novel bacterial isolates from healthy ginseng for the control of ginseng root rot disease (Fusarium oxysporum).

Ginseng root rot caused by Fusarium oxysporum is serious disease that impacts ginseng production. In the present study, 145 strains of bacteria were isolated from the rhizosphere soil of healthy ginseng plants. Three strains with inhibitory activity against Fusarium oxysporum (accession number AF077393) were identified using the dual culture tests and designated as YN-42(L), YN-43(L), and YN-59(L). Morphological, physiological, biochemical, 16S rRNA gene sequencing and phylogenetic analyses were used to identify the strains as Bacillus subtilis [YN-42(L)] (accession number ON545980), Delftia acidovorans [YN-43(L)] (accession number ON545981), and Bacillus polymyxae [YN-59(L)] (accession number ON545982). All three isolates effectively inhibited the growth of Fusarium oxysporum in vitro and the antagonistic mechanism used by the three strains involved the secretion of multiple bioactive metabolites responsible for the hydrolysis of the fungal cell wall. All three biocontrol bacteria produce indoleacetic acid, which has a beneficial effect on plant growth. From our findings, all three antagonistic strains can be excellent candidates for ginseng root rot caused by the pathogenic fungus Fusarium oxysporum. These bacteria have laid the foundation for the biological control of ginseng root rot and for further research on the field control of ginseng pathogens.

First Study Case of Microbial Biocontrol Agents Isolated from Aquaponics Through the Mining of High-Throughput Sequencing Data to Control Pythium aphanidermatum on Lettuce.

Aquaponics is defined as a sustainable and integrated system that combines fish aquaculture and hydroponic plant production in the same recirculated water loop. A recent study using high-throughput sequencing (HTS) technologies highlighted that microbial communities from an aquaponic system could control one of the most problematic pathogens in soilless lettuce culture, namely, Pythium aphanidermatum. Therefore, this study aims at isolating the microorganisms responsible for this biocontrol action. Based on the most promising genera identified by HTS, an innovative strategy for isolating and testing original biocontrol agents from aquaponic water was designed to control P. aphanidermatum. Eighty-two bacterial strains and 18 fungal strains were isolated, identified by Sanger sequencing, and screened in vivo to control damping-off of lettuce seeds caused by P. aphanidermatum. Out of these 100 isolates, the eight most efficacious ones were selected and further tested individually to control root rot disease caused by the same pathogen at a later stage of lettuce growth. Strains SHb30 (Sphingobium xenophagum), G2 (Aspergillus flavus), and Chito13 (Mycolicibacterium fortuitum) decreased seed damping-off at a better rate than a propamocarb fungicide and a Pseudomonas chlororaphis registered biocontrol agent did. In root rot bioassays, lettuce mortality was prevented by applying strains G2 and Chito13, which were at least as efficacious as the fungicide or biopesticide controls. Lettuce disease symptoms and mortality were eradicated by strain SHb30 in the first bioassay, but not in the second one. These results show that aquaponic systems are promising sources of original biocontrol agents, and that HTS-guided strategies could represent interesting approaches to identify new biocontrol agents.

Screening of antagonistic strains <i>Trichoderma</i> Pers. towards causative agent of root rot in apples of genus Fusarium Link.

In recent years, in the south of Russia, fungi of the genus Fusarium Link (1809) constitute a special danger to such important agricultural perennial crops as the apple tree. Тhese fungi cause root rot, a harmful disease, which weakens the vascular organs, leading to a significant decrease in yield and even death of the plant. A literature review showed that the genus Trichoderma has great potential for the integrated protection of apple trees. In this regard, due to the lack of registered microbiological agents for the control of fusarium root rot in apple trees, the search for antagonistic strains for biotechnological control of this disease becomes relevant. In this work, the parasitic activity of strains of the genus Trichoderma against the causative agents of root rot in apple trees, namely Fusarium sporotrichioides and Fusarium oxysporum, was studied in vitro. Тhe research was carried out in 2020–2021 in the Laboratory of biotechnological control of phytopathogens and phytophages of the FGBSO “North Caucasian Federal Scientific Center of Horticulture, Viticulture and Winemaking”. Тhe research was focused on monoconidial strains of the causative agent of apple root rot: F. sporotrichioides (strain RR20XXIV/4.3) and F. oxysporum (strain RR20XXV/6.2), as well as 7 strains of the genus Trichoderma having expected antagonistic activity. Тhe activity of strains of the genus Trichoderma against fungi of the genus Fusarium was determined by the dual culture method using joint splicing on the PGA medium (potato-glucose agar). Тhe Trichocin, SP (titer 1010 CFU/g Trichoderma harzianum, strain G-30 VISR), registered against root rot for a number of crops, was used as a standard. A monoculture of the test object (strains of the genus Fusarium) was used as a control. Out of the 7 strains of antagonistic fungi, strains 20I/1 and 20II/2 showed the greatest activity against F. sporotrichioides by a dual mechanism of action, which involves competition for a nutrient medium and fungicidal parasitic antagonism; the latter strain showed hyperparasitism. Antibiotic (strain 20XIV/5) and alimentary antagonisms (strain 20II/3.2) were also detected. Strain 20XIV/5 showed antibiotic antagonism against F. oxysporum, having higher activity than the standard; strain 20I/1 showed alimentary antagonism. Тhe remaining antagonist strains showed competitive interactions for the environment.

Biocontrol of root rot in Geranium with antimycotic rhizobateria

Excessive and frequent usage of synthetic fungicides has negative effects on the environment and human health. Biological control is one of the most efficient and environmentally responsible ways to manage plant diseases. In the present study, Bacillus velezensis strain B63, Bacillus subtilis subsp. Spizizenii strain TRC-20S and Serratia sp. Showed antifungal activities against Fusarium semitectum (synonym: Fusarium incarnatum), Macrophomina phaseolina, and Efibula tuberculata (MW063610) (synonym: Phanerochaete tuberculata). These fungi were isolated and purified from rotten geranium roots. M. phaseolina and F. semitectum were identified based on morphological and microscopic features. In addition, E. tuberculata was identified using the PCR technique. Bacillus velezensis strain B63 gave the best results in the terms of a decrease in plant mortality percentage and an increase in the geranium biometric parameters either under greenhouse or under field conditions. In addition, Bacillus velezensis strain B63 successfully increased the activity of defense-related enzymes, peroxidase (POD), and superoxide dismutase (SOD) and boosted the accumulation of total phenolic and flavonoid content in geranium leaves under field conditions. Also, the maximum essential oil yield with the highest eugenol content was recorded due to the application of B. velezensis and B. subtilis. Furthermore, anatomical analysis confirmed the positive role of biological control to induce resistance to root rot diseases through increasing root diameter, cortex thickness, vascular cylinder dimension, mean xylem vessel diameter, and xylem vessel number. Bacillus velezensis strain B63 possesses a broad expanse of antifungal and plant growth-promoting properties and can therefore play a vital role in boosting sustainable agriculture. This strain could be developed and applied in field experiments to improve plant growth and control root rot pathogens.

Control of Phytophthora and Rhizoctonia Root Rot on Red Maple Using Fungicides and Biofungicides

Phytophthora nicotianae and Rhizoctonia solani are the well-described soilborne pathogens of concern causing Phytophthora and Rhizoctonia root rot, respectively, of red maple plants (Acer rubrum L.), resulting in substantial economic losses to nursery growers. The management of root and crown rot disease of red maple is a big challenge. The objective of this study was to test the efficacy of several fungicide and biofungicide products to control Phytophthora and Rhizoctonia root rot on red maple plants in greenhouse conditions. Treatments, including fungicides and biofungicides, and nontreated and inoculated and nontreated and noninoculated as controls were arranged in a completely randomized design with six replications. Red maples planted in number 1 nursery containers were artificially inoculated with P. nicotianae or R. solani. Plant height, plant width, total fresh weight, and root fresh weight were measured and roots were assessed for root rot disease severity based on a scale of 0% to 100% root damaged. The pathogen recovery percentage of plant roots was determined by culturing ten randomly selected root pieces (≈1 cm long) cut from the root tips on Phytophthora selective medium (PARPH-V8) or Rhizoctonia semi-selective medium. All tested fungicides and biofungicides reduced Phytophthora and Rhizoctonia root rot on red maple plants compared with the nontreated and inoculated control. Likewise, pathogen recovery was lower for fungicide-treated and biofungicide-treated plants. Fungicides, such as mefenoxam, oxathiapiprolin, pyraclostrobin plus boscalid, and pyraclostrobin provided the most effective control of Phytophthora root rot. Pyraclostrobin plus boscalid and pyraclostrobin followed by biofungicides Bacillus amyloliquefaciens strain F727 and Trichoderma harzianum Rifai strain T-22 plus T. virens strain G-41 were most effective for suppressing Rhizoctonia root rot. There were no differences in plant height, plant width, plant fresh weight, and root fresh weight among the treatments. These findings will help nursery producers make decisions while formulating soilborne disease management strategies for red maple production.

Efficacy of Trichoderma species as bio-control agents to control root rot disease of Cantaloupe plants under the impact of climate change

Efficacy of Trichoderma species as bio-control agents to control root rot disease of Cantaloupe plants under the impact of climate change

Biocontrol activity and action mechanism of Bacillus velezensis strain SDTB038 against Fusarium crown and root rot of tomato.

Fusarium crown and root rot of tomato is a soilborne diseases that has brought serious harm and economic losses to tomato production in facilities in recent years. The disease has been reported in more than 30 countries worldwide, but there are few reports on its biological control. A Bacillus velezensis strain SDTB038 with biocontrol effects was isolated and identified in a previous study and is considered one of the most important PGPRs. Seven secondary metabolite biosynthesis gene clusters were found in strain SDTB038 by whole genome sequencing, explaining its biocontrol effects. Results indicated that different concentrations of SDTB038 fermentation broth inhibited the mycelial growth of Fusarium crown and root rot of tomato. Strain SDTB038 could generate indole acetic acid and promote healthy growth of tomatoes, while the effect of 108 CFU/ml SDTB038 concentration on promoting tomato growth was the most obvious. B. velezensis SDTB038 significantly reduced the accumulation of ROS in tomato plants, induced the up-regulation of antifreeze genes, and promoted the rapid recovery of tomato plants at low temperatures in a pot experiment. At the same time, SDTB038 had good control effect on Fusarium crown and root rot of tomato, and 108 CFU/ml SDTB038 fermentation broth had the best control effect, which was 42.98%. In summary, the strain B. velezensis SDTB038 may be a promising bacterial agent for biological control of Fusarium crown and root rot of tomato, and an important source of potential antimicrobial compounds.