Black Root Rot Disease Research Articles

Efficacy of Pseudomonas fluorescens and Organic Amendments Against Black Root Rot Disease Caused by Rhizoctonia solani in strawberry (Fragaria x ananassa Duch.)

Black root rot of strawberry caused by Rhizoctonia solani is one of the devastating soil borne disease. An experiment was conducted to evaluate the efficacy of organic amendments, PGPR (Pseudomonas Fluorescens) and botanical treatment for the management of R. solani on strawberry. The study was laid out in Randomized Block design (RBD) including 4 r eplications with 8 treatments in pot condition at the greenhouse of Department of Plant Pathology, Sam Higginbottom University of Agriculture, Technology and Sciences, Prayagraj, Uttar Pradesh, during Rabi season 20232024. The treatments consisted of combination of FYM, vermicompost, biomix compost, neem cake, cocopeat and botanical neem leaf extract were used as soil amendments and P. fluorescens as root treatment for evaluation on the plant growth, yield, physicochemical parameters (TSS and total ascorbic acid), disease intensity (%) and benefit cost ratio of strawb erry. The present investigation results revealed that T7 – P. fluorescens (0.3%) + FYM @ 100g + biomix compost @ 15g + vermicompost @ 15g + neem leaf extract @10% had the most promising results in term of maximum plant height (14.9 cm), maximum leaf number(15.75), days taken to first flowering (86 days), berry length (4.08 cm), berry diameter (2.84 cm), yield (38.87 qha-1), TSS (8.80 °Brix), total ascorbic acid (51.60mg/100g) and B:C ratio (1:2.24). It was also observed that T7 superior over other treatments giving least per cent disease intensity (30.75 %) followed by T6 – FYM @1 00g + P. fluorescens (0.3%) + biomix compost @15g + neem cake @15g + neem leaf extract @10% (35.50%). These findings highlight the potential of organic amendments, PGPR (P. fluorescens) and botanical treatments, as effective alternatives for managing black root rot disease caused by R. solani in strawberry cultivation.

Promising antifungal behavior of biosynthesized bimetallic silver-copper oxide nanoparticles and Bacillus safensis against some strawberry rots

Promising nanomaterials combined with beneficial microbes contributed to bio-modulations that might increase yields. In order to combat several fungal infections that invade strawberries (Fragaria ananassa), this study assessed the interactions between the synthesized CuO NPs, bimetallic Ag–CuO NPs, and Bacillus safensis (BS-22) under various treatment circumstances. The effectiveness of BS-22, CuO NPs, and bimetallic Ag–CuO NPs against four different pathogens that cause gray mold disease and root rot on strawberry plants was determined. It was possible to successfully extract twenty-four endophytic bacterial isolates from hygienic strawberry plants that were indigenous. BS-22 isolate, which produced the most hydrogen cyanide (HCN), siderophores, gibberellic acid (GA3), and indole-3-acetic acid (IAA), was identified molecularly as Bacillus safensis. The most extensively studied treatments (foliar CuO NPs at 200 ppm + foliar Ag–CuO NPs at 200 ppm + BS-22) decreased the frequency and severity of black root rot disease in strawberry plants. Foliar CuO NPs (50 ppm) + foliar Ag–CuO NPs (50 ppm) showed significant increase of the total suspended solids (TSSs), total antioxidant capacity (TAC) content, and the total polyphenols content compared to the control and other treatments. The same treatment recorded the highest value in all characters of cell wall components except lignin character where BS-22 treatment had the best effect. All tested treatments significantly decreased disease incidence and severity when strawberry fruit stored at 22 °C ± 2 for 25 days on average. According to this study, foliar CuO NPs (200 ppm) + foliar Ag–CuO NPs (200 ppm) + BS-22 (as a soil drench) might be used as a substitute for gray mold and root rot diseases in strawberry development and biocontrol.

First report of root rot of strawberry caused by Fusarium cugenangense, a member of the F. oxysporum species complex, in Tennessee, USA.

Strawberry (Fragaria × ananassa Duch) in Tennessee is cultivated on plastic mulched beds annually, and production is limited primarily by multiple oomycete and fungal root rot pathogens that result in reduced vigor and black root rot disease symptoms. In early June 2018, plants (cv. Chandler) with reduced shoot vigor and size, and black, necrotic stunted roots were collected from Rhea County, TN. Roots and crowns of 10 plants were cut into 1-3 cm pieces and surface sterilized with 0.6% NaOCl, followed by 70% ethanol for 1 min each, and plated on water agar. White mycelia produced after 3 days were transferred to potato dextrose agar amended with 10 mg/liter rifampicin. After 10 days, fungal colonies were light purple on the surface and dark purple on the colony underside, later developing blue-black pigmentation on the underside. Microconidia on carnation leaf agar were ovoid to ellipsoid, aseptate or septate and 8.0 to 24.2 (13.7) × 3.0 to 4.5 (3.8) μm in size, macroconidia were 3 to 5 septate and falcate to almost straight and 33.7 to 52.8 (44.4) × 4.0 to 5.5 (4.9) μm in size (n=80); both conidia were produced on monophialides. Chlamydospores were globose and subglobose, formed terminally and intercalary on aerial, submerged, and surface mycelium, singly or in pairs and were abundantly produced in sucrose broth and on synthetic nutrient-poor agar (SNA) (diam. 7.6 μm). Morphology was consistent with Fusarium oxysporum (Leslie and Summerell, 2006) and F. cugenangense, a member of the F. oxysporum species complex, as described by Maryani et al. (2019). Fungal mycelia were used for PCR (Phire Plant Direct PCR Master Mix, Thermo Scientific, CA) and the translational elongation factor 1-α (EF1α) region was amplified with primers EF-1/EF-2 (O'Donnell et al., 1998), internal transcribed spacer (ITS) regions amplified with primers ITS1/ITS2 (White et al. 1990), and the RNA polymerase second largest subunit region (RPB2) with primer pairs 5f2/7cr and 7cf/11ar (O'Donnell et al., 2022). PCR products of isolate SC5 were sequenced, and sequences compared to all sequences in the FUSARIOID-ID database using polyphasic identification (Crous et al., 2021) with EF1α (GenBank Accession No. ON703236) and RPB2 (OR472390) sequences. The highest similarity (100%) was with isolates of F. cugenangense, including ex-type isolate InaCC F984 (99.94% similarity) (Maryani et al., 2019). F. cugenangense is closely related to F. callistephi and F. elaeidis, but both species lack chlamydospores, and F. elaeidis has polyphialides (Lombard et al, 2019). To satisfy Koch's postulates, healthy rooted strawberry plants produced in soilless media were transplanted into 4 plastic pots (1.2-liter) containing 5% (w/v) fungal inoculum (grown on barley grain) and mixed into the top 5-cm of peat-based soilless medium. Pots were incubated at 25°C and 50% RH in a growth chamber. Four pots without inoculum served as controls. The trial was repeated. Within 8 weeks, all inoculated plants had low vigor, with necrotic and stunted roots. Root sections of control and inoculated plants were plated, and the pathogen was re-isolated from diseased roots of all inoculated plants only and confirmed as F. cugenangense based on morphology and sequence analysis. To our knowledge, this is the first report of F. cugenangense, or any member of the F. oxysporum species complex, causing root rot of strawberry in Tennessee and could be an important component of the production-limiting black root rot disease complex of strawberry.

Investigations on black root rot disease of mulberry caused by Lasiodiplodia theobromae

Mulberry is an important food plant for domesticated silkworm (Bombyx mori L.). Among several root rot diseases reported in mulberry, black root rot caused by Lasiodiplodia theobromae has now emerged as a major disease. The survey was conducted and black root rot incidence was found to be maximum (51.7%) in Coimbatore district and minimum (14.1%) in Erode district. On PDA, L. theobromae covered Petri plate within three days with cottony white fluffy and slowly turned to black colour. All the four isolates were identified by molecular characterisation through PCR with ITS region and sequences were deposited in NCBI database. Among biocontrol agents screened, Trichoderma asperellum TRI 15 and T. virens TRI 37 were found to be inhibitory with 67.7% and 66.6% reduction in mycelial growth. Five mulberry varieties were screened, variety G2 showed resistance and V1 was highly susceptible.

Management of Black Root Disease-Causing Fungus Fusarium solani CRP1 by Endophytic Bacillus siamensis CNE6 through Its Metabolites and Activation of Plant Defense Genes.

Black root rot disease of Cicer arietinum L. is accountable for substantial loss in chickpea production worldwide. Endophytic Bacillus siamensis CNE6 has previously shown multifaceted plant growth-promoting, broad-spectrum antifungal, and chickpea plant-colonizing potential. In the present study, the strain Bacillus siamensis CNE6 was used for controlling black root rot disease caused by Fusarium solani CRP1 in chickpea. CNE6 showed strong antagonistic potential against CRP1 both in vivo and in vitro. Scanning electron microscopic studies indicated cellular deformation of CRP1 due to production of β-glucanase, protease, and other secondary metabolites. A total of five compounds were detected from the cell-free supernatant (CFS) of the ethyl acetate (EA) fraction of CNE6 through gas chromatography-mass spectrometry analysis. A confocal microscopic study demonstrated strong inhibition of biofilm formation of the pathogen CRP1 by the EA fraction of CFS of CNE6. Molecular docking analysis revealed that one compound, (2E)-6-methoxy-2-[(4-methoxyphenyl)methylidene]-2,3-dihydro-1-benzofuran-3-one, may inhibit the activity of lanosterol 14-alpha demethylase, which is involved in ergosterol biosynthesis and beta-tubulin assembling. In vivo experiments also showed the efficacy of CNE6 for increasing chickpea growth as well as upregulation of four defense genes (CHI1, PAMP, PR2B, and TF1082) upon pathogenic challenge. Thus, our results strongly suggest a positive role for CNE6 as a prospective biocontrol agent for combating Fusarium solani in chickpea. IMPORTANCE The present work was undertaken to explore an effective biocontrol agent against the destructive black root rot disease of chickpea. We have used an efficient bacterial endophyte, CNE6, which can colonize in the chickpea root system, produce secondary metabolites and enzymes to degrade pathogenic cellular integrity, inhibit pathogenic establishment by rupturing biofilm formation, and induce host immunity upon treatment. Interaction of the bacterial metabolite was also observed with lanosterol 14-alpha demethylase, which is an important component in fungal membrane functioning. Being an endophyte, Bacillus siamensis CNE6 fulfills a suitable criterion as a biocontrol agent to control black root rot disease in chickpea and has huge prospects for use commercially.

Evaluation of artificial inoculation methods to determine resistance reaction to dry root rot and black root rot disease in mulberry (Morus spp.)

Root rot disease of mulberry is a widespread soil-borne disease, which can cause serious damage and huge economic loss to mulberry production in India. Efficient and reliable screening methods are prerequisites to evaluate the disease-resistant germplasm accessions for developing a cultivar’s resistance to root rot. A multifactor experiment with four replications was established to evaluate four different inoculation techniques namely, colonized sorghum grains (CSG), colonized toothpick, root dip (RD), and syringe inoculation using pathogenic isolates of three fungal pathogens; Fusarium solani, F. oxysporum (dry root rot) and Lasiodiplodia theobromae (black root rot) against known resistant and susceptible mulberry germplasm accessions under glasshouse conditions. In addition, all the methods of evaluating resistance were compared and the results indicated that CSG and RD methods of inoculation for dry and black root rot were stable in their pathogenic effect. Also, these two methods were easy to screen and more convenient than other methods.

Whole-Genome Resource of Lasiodiplodia pseudotheobromae BaA, the Causative Agent of Black Root Rot Morinda officinalis.

Whole-Genome Resource of Lasiodiplodia pseudotheobromae BaA, the Causative Agent of Black Root Rot Morinda officinalis.

Evaluation of Fungicide Soil Drench Treatments to Manage Black Root Rot Disease of Avocado.

Four common fungicidal products were evaluated for their effect on symptoms caused by two nectriaceous black root rot fungi, Calonectria ilicicola and Dactylonectria macrodidyma, when applied as pot drenches to avocado (Persea americana) seedlings in the greenhouse. Applications of fludioxonil, thiophanate-methyl + etridiazole, prochloraz, and prochloraz MnCl at 2 and 4 weeks after inoculation with C. ilicicola significantly reduced root necrosis and improved root and aboveground plant biomass compared with water-treated controls. Fludioxonil reduced necrosis by 60% and had a significantly lower frequency of reisolation of C. ilicicola than the other three fungicide treatments. D. macrodidyma inoculation caused less severe symptoms in seedlings than C. ilicicola despite the longer duration of the trial. Pot drenches with fludioxonil, thiophanate-methyl + etridiazole, and prochloraz MnCl, but not prochloraz alone, significantly reduced root necrosis caused by D. macrodidyma. Prochloraz MnCl was the only fungicide treatment to increase root and plant biomass compared with water-treated controls. Both fludioxonil and prochloraz MnCl reduced the frequency of reisolation of D. macrodidyma from necrotic roots by about 50% compared with the other fungicides or water controls. The results indicated that drenches with these fungicides may suppress existing low to moderate black root rot infection, allowing new root growth and improved establishment in the orchard. Fungicide drenching must not replace best-practice disease management strategies in nurseries but may be a useful tool in crisis situations.

Native bacteria for field biocontrol of black root rot in Egyptian strawberry

BackgroundIncreasing cultivation of strawberry in Egypt has boosted efforts to increase its yield. Biocontrol agents (BCAs) may avoid side effects and health risks caused by chemical fungicides used to control black root rot disease in strawberry. Some BCAs control the disease and augment strawberry yield, but additional research is needed to fit BCAs into emerging control strategies. The impact of six bacterial isolates of Paenibacillus polymyxa and Bacillus brevis on this disease and on berry yield is reported and compared to a common chemical fungicide.ResultsThe bacterial isolates reduced the growth of the black root rot causal agents Fusarium solani, Rhizoctonia solani, and Macrophomina phaseolina, in dual culture bioassays. The greatest fungal inhibition was caused by P. polymyxa isolates 1 and 2 and B. brevis isolate 2. They suppressed the growth of F. solani, R. solani, and M. phaseolina by more than 74, 76, and 79%, respectively. Disease severity and incidence were significantly reduced on naturally infected strawberry plants in the field by the six isolates. The best results were obtained by the superior bioassay isolates which suppressed the disease incidence by 73, 77, and 71%, and its severity by 72, 78, and 70%, respectively. Disease suppression by bacteria was comparable to that by fungicide Actamyl. Bacteria surpassed Actamyl with regard to strawberry yield and enhancement of peroxidase and chitinase activities in the leaves.ConclusionsThese isolates are potential benign alternatives to fungicides used against black root rot in strawberry in Egypt. More studies are needed to examine their economic use on a wider scale.

Identification of Berkeleyomyces rouxiae causing black root rot disease on cotton seedlings in New South Wales, Australia

Identification of Berkeleyomyces rouxiae causing black root rot disease on cotton seedlings in New South Wales, Australia

Suppression of Strawberry Black Root Rot Disease in the Field by Chitosan Applied as Root Dipping and Foliar Spray

Suppression of Strawberry Black Root Rot Disease in the Field by Chitosan Applied as Root Dipping and Foliar Spray

In-vitro compatibility assay of indigenous Trichoderma and Pseudomonas species and their antagonistic activities against black root rot disease (Fusarium solani) of faba bean (Vicia faba L.)

BackgroundFaba bean (Vicia faba L.) cultivation is highly challenged by faba bean black root rot disease (Fusarium solani) in high lands of Ethiopia. To ensure sustainable production of faba beans, searching for eco-friendly disease management options is necessary to curb the progress of the disease timely. The indigenous biocontrol agents that suit local environments may effectively strive with in-situ microorganisms and suppress local pathogen strains. This study aimed to screen antagonistic indigenous compatible Trichoderma and Pseudomonas strains against Fusarium solani. In the pathogenicity test, soil-filled pots were arranged in complete random block design and sown with health faba bean seeds. The effect of some fungicides was evaluated against Fusarium by food poisoning methods to compare with the biocontrol agents. The antagonistic efficacy of biocontrol agents and their compatibility was investigated on Potato dextrose agar medium.ResultsFusarium solani AAUF51 strain caused an intense root rotting in faba bean plant. The effect of Mancozeb 80% WP at 300 ppm was comparable with Trichoderma and Pseudomonas strains against Fusarium. The mycelial growth of test the pathogen was significantly (P ≤ 0.05) reduced to 86.67 and 85.19% by Trichoderma harzianum AAUW1 and Trichoderma viridae AAUC22 strains in dual culture, respectively. The volatile metabolites of Pseudomonas aeruginosa AAUS31 (77.78%) found the most efficient in reducing mycelial growth of Fusarium followed by Pseudomonas fluorescens AAUPF62 (71.11%) strains. The cell-free culture filtrates of Pseudomonas fluorescens AAUPF62 and Pseudomonas aeruginosa AAUS31 were more efficient than the Trichoderma strain in reducing the growth of Fusarium isolates. There was no zone of inhibition recorded between Trichoderma harzianum AAUW1, Trichoderma viridae AAUC22, Pseudomonas aeruginosa AAUS31, and Pseudomonas fluorescens AAUPF62 strains, hence they were mutually compatible.ConclusionsThe compatible Trichoderma and Pseudomonas strains showed antagonistic potentiality that could be explored for faba bean protection against black root rot disease and might have a future dual application as biocontrol agents.

Application of Bacillus pumilus isolates for management of black rot disease in strawberry

BackgroundBlack root rot of strawberry plants caused by Rhizoctonia solani, Fusarium solani, and Pythium sp. is a serious disease in Egypt. Biocontrol agents have frequently proved to possess paramount and safe tools against many diseases. The impact of soil treatments with 3 Bacillus pumilus isolates on black root rot disease of strawberry plants caused by R. solani, F., and Pythium sp. under laboratory and field conditions was examined herein on the commonly used ‘Festival’ strawberry cultivar. To increase the bacterial adhesion and distribution on the roots, each seedling was dipped in bacterial cell suspension at 1 × 108 colony-forming units/ml of each separate bacterial isolate for 30 min then mixed with 5% Arabic gum.ResultsThe tested B. pumilus isolates significantly reduced the growth area of these 3 fungi. The two bacterial isolates Nos. 2 and 3 reduced the growth area by more than 85.2, 83.6, and 89.0% for R. solani, F. solani, and Pythium sp., respectively. Likewise, the 3 bacterial isolates significantly (P ≤ 0.05) inhibited the disease under field conditions. Isolates Nos. 2 and 3 suppressed the disease incidence by 64.4 and 68.9% and disease severity by 65.3 and 67.3%, respectively. The fungicide Actamyl had effect similar to that of the 2 isolates. B. pumilus isolates significantly enhanced growth parameters and yields of strawberry plants; isolates Nos. 2 and 3 raised the yield by 66.7 and 73.3%, respectively.ConclusionsBacillus pumilus isolates could effectively manage the black rot disease in strawberry herein. Due to the significant impact of the root rot disease on strawberry yield, B. pumilus should be further tested to manage the disease on strawberry on large scale in Egypt.

Conserved Markers Order in Quantitative Trait Loci Confers Resistance against Black Root Rot Disease in Cotton

Conserved Markers Order in Quantitative Trait Loci Confers Resistance against Black Root Rot Disease in Cotton

Comparative Study on the Fungicidal Activity of Metallic MgO Nanoparticles and Macroscale MgO Against Soilborne Fungal Phytopathogens.

Engineered nanoparticles have provided a basis for innovative agricultural applications, specifically in plant disease management. In this interdisciplinary study, by conducting comparison studies using macroscale magnesium oxide (mMgO), we evaluated the fungicidal activity of MgO nanoparticles (nMgO) against soilborne Phytophthora nicotianae and Thielaviopsis basicola for the first time under laboratory and greenhouse conditions. In vitro studies revealed that nMgO could inhibit fungal growth and spore germination and impede sporangium development more efficiently than could macroscale equivalents. Indispensably, direct contact interactions between nanoparticles and fungal cells or nanoparticle adsorption thereof were found, subsequently provoking cell morphological changes by scanning electron microscopy/energy-dispersive spectrometry (SEM/EDS) and transmission electron microscopy (TEM). In addition, the disturbance of the zeta potential and accumulation of various modes of oxidative stress in nMgO-exposed fungal cells accounted for the underlying antifungal mechanism. In the greenhouse, approximately 36.58 and 42.35% decreases in tobacco black shank and black root rot disease, respectively, could testify to the efficiency by which 500 μg/ml of nMgO suppressed fungal invasion through root irrigation (the final control efficiency reached 50.20 and 62.10%, respectively) when compared with that of untreated controls or mMgO. This study will extend our understanding of nanoparticles potentially being adopted as an effective strategy for preventing diversified fungal infections in agricultural fields.

Characterizations of antagonistic bacteria species against black root rot disease of faba bean (Vicia faba L.)

Characterizations of antagonistic bacteria species against black root rot disease of faba bean (Vicia faba L.)

Sowing maize as a rotation crop in irrigated cotton cropping systems in a Vertosol: effects on soil properties, greenhouse gas emissions, black root rot incidence, cotton lint yield and fibre quality

Although sowing winter cereal crops in rotation with irrigated cotton (Gossypium hirsutum L.) is practised by many Australian cotton growers, summer cereals such as maize (Zea mays L.) are sown more frequently than previously. Our objective was to quantify the impact of sowing maize rotation crops on soil properties, greenhouse gas emissions, incidence of black root rot (BRR) disease and crop yields in an ongoing long-term experiment located in a Vertosol in north-western New South Wales. The historical treatments were cotton monoculture (sown after either conventional or minimum tillage) and a minimum-tilled cotton–wheat (Triticum aestivum L.) rotation. The experiment was redesigned in 2011 by splitting all plots and sowing either maize during summer following the previous year’s cotton or retaining the historical cropping system as a control. pH and exchangeable cation concentrations were highest, and electrical conductivity (EC1:5) lowest during 2012, the season following a flood event, but were unaffected by sowing maize. In subsequent seasons, with the onset of dry conditions, pH and cation concentrations decreased, and EC1:5 increased. The upper horizons (0–0.3 m) of plots where maize was sown had higher concentrations of exchangeable Ca and Mg during 2012, and 0.45–1.20 m had higher concentrations of exchangeable Na and exchangeable sodium percentage, but these differences disappeared in subsequent years. Soil organic carbon (SOC) in the surface 0.15 m was higher with maize, with differences becoming evident three years after maize was first sown but without any increases in SOC storage. Soil under maize was less resilient to structural degradation. BRR incidence was lower in maize-sown plots only during 2012. Stepwise linear regression suggested that high concentrations of exchangeable Ca and Mg in the surface 0.15 m played a role in reducing BRR incidence during 2012. Maize rotation introduced into cotton monocultures improved lint yields and reduced greenhouse gas emissions but had little impact in a minimum-tilled cotton–wheat rotation. Maize is a suitable rotation crop for irrigated cotton in a two-crop sequence but is of little advantage in a cotton–wheat–maize sequence.

Efficacy of soil solarization on black root rot disease and speculation on its leverage on nematodes and weeds of strawberry in Egypt

BackgroundStrawberry (Fragaria ananassa Duch.) is an economically important crop in Egypt. Yet complex black root rot disease of strawberry caused by Fusarium solani, Rhizoctonia solani, and Pythium sp. can cause considerable yield losses. Therefore, this study aimed at evaluating different aspects of soil solarization against this disease. Such an evaluation would better be viewed in the context of other beneficial effects of soil solarization on nematodes and weeds.Materials/methodsGrowth agar disks, growth suspension, and resting stages of strawberry black root rot fungi were evaluated at different temperatures and exposure times using digital hot water bath. Cloth bags artificially infested with single fungal species were buried into the soil before soil solarization at soil depths of 1–10, 11–20, and 21–30 cm at three spots of each plot for each of the abovementioned fungi for 3, 6, or 9 weeks. The disease incidence and severity in solarized and un-solarized soil was compared with the application of the fungicide Actamyl. Effects of soil solarization on nematodes and weeds were also consulted.ResultsThe lethal temperature to F. solani, Pythium sp., and R. solani was 58, 58, and 56 °C, respectively when exposure time was 1 min. Chlamydospores were killed at 62 °C while sclerotia were killed at 58 °C in hot water for 1 min. Maximum soil temperature in solarized soil was raised by 15, 14, and 12 °C at depths of 1–10, 11–20, and 21–30 cm as compared with non-solarized soil. Solarization for 3, 6, and 9 weeks significantly reduced the disease incidence and severity and increased the strawberry yield. Complete reduction in total count of all tested fungi was obtained after 9 weeks at all tested depths. A review of collective soil pest and pathogen control via solarization documented its beneficial application.ConclusionThe study may exploit hot months in Egypt for soil solarization against the serious root rot disease either singly or in an integrated pest management program.

Local Trichoderma strains as a control strategy of complex black root rot disease of strawberry in Egypt

BackgroundEconomics and human safety to avoid health risks caused by fungicides are materializing new era of biological pest control. Trichoderma species ranked high among other agents to control complex black root rot disease of strawberry caused by Fusarium solani, Rhizoctonia solani, and Pythium sp. Our study aimed to document the efficacy of local strains representing T. harzianum, T. viride, T. virinis, and T. koningii against such a disease.Materials/methodsThese strains were cultured separately on potato dextrose broth medium to test their inhibitory effect against strawberry black root rot in vitro and in vivo. Strawberry growth and yield were also assessed relative to the untreated check and the fungicide Actamyl. Activity of peroxidase and chitinase were measured in plant leaves using spectrophotometer.ResultsEach of the antagonistic fungal strains significantly reduced growth area of all pathogenic fungi collectively causing the disease. Trichoderma harzianum, T. viride, and T. koningii reduced the growth area more than 90.6% for all tested pathogenic fungi. Each species significantly reduced disease incidence and severity under field conditions. The highest reduction in the disease incidence and severity, 83.3 and 88.5% respectively, was attained by mixture of the four species. This mixture increased the strawberry fresh and dry weight by 83.3 and 176.9%, respectively, and the yield by 117.1%. All Trichoderma species tested significantly increased the activity of two plant defense-related enzymes of strawberry plants against the pathogens. Their mixture attained the highest increase of peroxidase and chitinase activity by 150 and 160.9%, respectively.ConclusionsWhile the fungal mixture could considerably increase the strawberry fresh and dry weight as well as the yield, it suppressed the incidence and severity of the disease. So, integrated pest management in ways that make these biocontrol agents complementary or superior to chemical fungicides should further be examined against this disease.

New occurrences of Botryosphaeriaceae causing black root rot of cassava in Brazil

Despite the occurrence of several diseases of cassava, the cassava black root rot (CBR) represents one of the main limiting factor for crop rentability in the world. However, the etiology of CBR is complex and it needs to be revised based on current molecular analysis. On this work, molecular and morphological studies allowed for the identification of three species of Botryosphaeriaceae causing black root rot disease of cassava in the states of Maranhao and Paraiba, Brazil, namely: Lasiodiplodia euphorbicola, Lasiodiplodia pseudotheobromae and Neoscytalidium hyalinum. This is the first report of these three fungal species as causal agents of CBR in the world.