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Despite our emergent understanding of the contribution of beneficial microbes to the health of humans and the crops we eat, microbiome engineering to improve plant health has had limited success. Recent work has shown that plant genotype plays a critical role in shaping the plant microbiome and so plant genetics must be considered in engineering practices. Here, we review recent work from our lab and others on plant-driven genetic and molecular mechanisms that shape plant-associated microbial communities. Based on our emergent understanding of plant-driven recruitment of beneficial microbes, we discuss challenges in Canadian agriculture that are strong candidates for microbiome engineering. These include pathogens that have been difficult to control through traditional methods including root rot pathogens, as well as controlled agricultural systems like greenhouses and vertical farming. Finally, we discuss knowledge gaps to achieve successful microbiome engineering that can be filled with basic research, particularly through the use of model plant systems. [ABSTRACT FROM AUTHOR]

The mitochondrial genome of Dematophora necatrix is 121,350 base pairs in length with a G + C content of 30.19%. Phylogenetic analysis showed that D. necatrix grouped with other members of the Xylariaceae, with which its mitogenome also shares a broadly similar architecture and gene content. The D. necatrix mitogenome contains 14 protein-coding and 26 tRNA-encoding genes, as well as one copy each of the rnl, rns, rps3 and nat1 genes. However, as much as 80% of this genome is intronic or non-coding. This is likely due to expansions and rearrangements caused by the large number of group I introns and the homing endonucleases and reverse-transcriptases they encode. Our study thus provides a valuable foundation from which to explore the mitochondrion's role in the biology of D. necatrix, and also serves as a resource for investigating the pathogen's population biology and general ecology. [ABSTRACT FROM AUTHOR]

AbstractWestern white pine (Pinus monticola) with genetic tolerance to white pine blister rust disease caused by Cronartium ribicola constitutes an invaluable resource for the mitigation of this disease as well as the restoration of the species and its utilization in managed forests. In the last several years, typical root-rot symptoms and sudden tree death have been observed in some western white pine plantations located in British Columbia (BC) in Canada, and a few Phytophthora species were found to be associated with symptomatic trees. Our objectives were to survey one of the plantations located in south-west BC on Vancouver Island to confirm the presence of these Phytophthora species and other oomycetes and test their pathogenicity on western white pine by completing Koch’s postulates. We used direct plating of root samples on PARP(H)-CMA media and by baiting for oomycetes in soil and root samples. Ten oomycetes, including four Phytophthora species (Phytophthora cinnamomi, P. cactorum-like, P. cryptogea and P. pseudocryptogea) were isolated from roots and soil samples of diseased Pi. monticola trees. The Phytophthora species were identified using ITS, β-tubulin and TEF1 gene regions. Koch’s postulates were validated with controlled inoculations of 1-year old seedlings; mortality occurred as early as 15 days after inoculation with P. cinnamomi when the seedlings were maintained in warm temperature conditions (25°C). Molecular typing of two P. cinnamomi cultures using Oxford Nanopore MinIONTM sequencing indicated that they belong to one of the two main clonal clusters of mating type A2 that have been recognized as the main drivers of the global P. cinnamomi epidemic. [ABSTRACT FROM AUTHOR]

Soilborne fungal pathogens that cause root rot, wilting and dying are the most important problems in pistachio production. The purpose of this study was to examine, isolate, and diagnose the pathogens from diseased pistachio trees in orchards and nurseries located in southeastern Turkey. Fungi isolated from the pistachio trees were identified by morphology and the sequences of the internal transcribed spacer (ITS) region and translation elongation factor-1α (TEF-1α). Fusarium solani, Fusarium oxysporum, Fusarium brachygibbosum, Fusarium chlamydosporum and Macrophomina phaseolina were the most important fungi causing root rot, wilting and decline of pistachio trees. Pathogenicity studies showed that all of the fungi identified can colonize and damage the vascular tissues of a sapling and cause substantial lesions and vascular discolourations. This study provides the first evidence of wilting due to the root and crown rot in pistachio trees in Siirt province of Turkey caused by some Fusarium species, especially F. solani, F. oxysporum, F. chlamydosporum, F. brachygibbosum and M. phaseolina. Finally, the research enabled the identification of some fungal pathogens that are seriously harming pistachio trees in southeastern Turkey. [ABSTRACT FROM AUTHOR]

Seedling rot in sugar beet was observed at Snyder Farms, Wyoming, USA, in April 2022. The diseased seedlings exhibited water-soaked brown to blackish lesions in hypocotyls with poor root systems. Four fungal isolates were retrieved from the diseased samples, and their morphological features were found to be identical to those of previously reported Fusarium species. Artificial inoculation with isolates developed similar symptoms to those observed in the field samples. Based on morphological characteristics, pathogenicity assays, sequence homologies of the internal transcribed spacer, translation elongation factor (tef1α), largest subunit of RNA polymerase II (rpb2), β-tubulin (β-tub), and multilocus phylogenic analyses with tef1α and rpb2, the causal agent was identified as Fusarium clavum (F. incarnatum-equiseti species complex 5). This is the first worldwide report of sugar beet seedling rot caused by F. clavum, detected in Wyoming, USA. This finding will help to formulate effective management practices to manage the pathogen and prevent its widespread occurrence. [ABSTRACT FROM AUTHOR]

The study investigated the effectiveness of seed dressing and foliar spray with indole acetic acid (IAA), gibberellic acid (GA) and Trichoderma harzianum, either alone or in combination, to manage root rot in green beans. The application of GA at concentrations of 40 ppm, 20 ppm, IAA at 20 ppm, 40 ppm and a combination of IAA at 40 ppm and GA at 40 ppm significantly reduced the incidence of pre-emergence root rot. Additionally, the use of IAA at concentrations of 10, 20 and 40 ppm completely suppressed post-emergence root rot in green beans. Furthermore, the application of tested growth regulators IAA and GA at different concentrations along with T. harzianum in combination induced higher chitinase polyphenol oxidase and phenylalanine ammonia-lyase activities compared to control. These treatments have the potential to be used as safe and effective alternatives to chemical fungicides for the control of green bean root diseases. [ABSTRACT FROM AUTHOR]

Root rot caused by Heterobasidion spp. is the most serious fungal disease of conifer forests in the Northern Hemisphere. In Scots pine (Pinus sylvestris L.) stands infected by H. annosum, root rot reduces sawlog quality due to decay and resin-soaked patches. Automatically detecting the disease during harvesting operations could be used to optimize bucking as well as to efficiently collect data on root-rot incidence within forest stands and at larger geographical scales. In this study, we develop deep learning models based on convolutional neural networks to automatically detect root rot disease and the presence of resinous wood in stem end images of Scots pine. In addition, we study the effect of pre-filtering the images via a classical texture operator prior to model development. Using transfer learning on pre-trained feature extractor networks, we first construct classifiers for detecting severely rotten wood in stem end images. Second, we develop a classifier for detecting the presence of resin outside branch knots. In rot detection, using regular RGB images, our final model reaches a binary classification accuracy of (63 ± 6)% on the independent test data, where the error is the standard error. Pre-processing the images using the classical texture operator increases the final classification accuracy to (70 ± 6)%. To detect only resin using regular RGB images, we find an accuracy of (80 ± 6)%. Finally, we discuss the operational implications and requirements of implementing such computer vision algorithms in the next generation of forest harvesters. [ABSTRACT FROM AUTHOR]

Phytophthora capsici is a major oomycete-based pathogen causing enormous damage to the productivity of peppers and other major crops from different families worldwide by causing fruit rot, root rot and foliar blight diseases. This study utilized molecular signatures present within ITS1-5.8S rRNA-ITS2 and Ras-related GTP binding protein (Ypt1) genes to evaluate haplotype variability and phylogenetic relationships among P. capsici isolates with significant epidemiological implications. Twelve different evolutionary lineages specific to particular hosts and/or geographical regions and differed by SNPs, and 30 haplotypes with maximum diversity in India and Pakistan, were identified by sequence analysis of the ITS regions. It includes country-specific lineages Pc-I and Pc-II in India with multiple host ranges; capsicum-specific lineages Pc-IV, Pc-V and Pc-VIII from Pakistan; papaya-specific lineages Pc-VI from China, and watermelon-specific lineages Pc-VII and Pc-XI from USA. Many lineages showed cross-border infections, such as Pc-III and Pc-X in India and Pakistan, Cocoa-specific lineage Pc-IX in Brazil and Cote d'Ivoire, and Capsicum-specific multi-continental lineage Pc-XII. Similarly, 11 different SNP lineages and 32 haplotypes with maximum diversity in China were identified for the Ypt1 gene. These findings would be very useful for epidemiological surveillance of P. capsici strains worldwide, understanding population and evolutionary dynamics, developing lineage- and haplotype-specific diagnostic assays and disease-resistant varieties. [ABSTRACT FROM AUTHOR]

The understanding of how solitary and combined use of covercrop species and seeding rates influences soilborne diseases is lacking. Cover crops (crimson clover, triticale and crimson clover + triticale) were seeded in the field plots in September 2019 (Trial 1) and September 2021 (Trial 2) at two seeding rates (low and high) and a no cover cropped fallow served as a control. The soil was collected from all the plots in the following June. Red maple rooted cuttings were planted in nursery containers filled with those soils and plant health was evaluated with and without inoculation with Phytophthora nicotianae, Phytopythium vexans and Rhizoctonia solani. Plant height and fresh weight were measured, and plant roots were assessed for root rot severity (0–100% roots affected) and pathogen recovery. The number of fluorescent Pseudomonads present in soil samples was counted. Root rot severity and pathogen recovery were less with plants grown in cover cropped soil compared to non-cover cropped soil. Root rot severity caused by all three pathogens was least with the plants grown in the crimson clover and mixed cover cropped soil with the mixture being better than crimson clover. Moreover, plants grown in the high rate of cover cropped soil had less root rot severity compared to plants grown in low seeding rate cover cropped soil. Plant fresh weight was greater for plants grown in the high rate of crimson clover cover cropped soil and, in the mixture, compared to the non-cover cropped soil, whereas height was least affected. The Pseudomonad population was greatest in mixed cover cropped as well as in the high rate of cover cropped soil. Our findings suggest that a mixture of cover crop species and high seeding rate provides better service in suppressing root rot diseases likely associated with biological processes and nutrient availability. [ABSTRACT FROM AUTHOR]

Aurisin A (1) and the culture medium of the luminescent mushroom Neonothopanus nambi showed antifungal activity against Phytophthora palmivora, which causes the root-rot disease of Monthong durian, in a preliminary greenhouse experiment. Moreover, a new natural product, neonambiquinone B (2), was isolated. Their structures were elucidated by mass, IR and extensive analysis of their 1D and 2D NMR spectroscopic data. The results demonstrated that the culture medium of N. nambi is a promising potential for their agricultural applications. [ABSTRACT FROM AUTHOR]

Oomycetes are devastating soil-borne plant pathogens, and cause numerous losses on diverse crops worldwide. In this study, our aim was to identify actinomycetes with antimicrobial activity towards oomycetes from the rhizosphere of soybean. Strong growth inhibition of P. myriotylum was found in dual culture with a strain called 11 × 1, and also from using the 11 × 1 cell-free culture filtrate and EtOAc extract. The P. myriotylum growth-inhibiting activity of the 11 × 1 culture filtrates was stable at high temperatures, and acidic and alkaline conditions. The 11 × 1 strain was identified as a Streptomyces strain with the highest 16S rDNA sequence identity to S. scabiei, and phylogenomic analysis also showed clustering with S. scabiei strains. Applying the 11 × 1 culture filtrates to ginger and soybean leaves inhibited the necrosis caused by P. myriotylum and P. sojae, respectively. Pot assay experiments showed a strong control effect of the 11 × 1 culture filtrate against P. myriotylum-caused soft-rot disease of ginger, and against P. sojae caused root-rot of soybean. Analysis of the biosynthetic gene clusters from the genome of 11 × 1 predicted the production of staurosporine, and staurosporine was subsequently identified from LC-MS analysis of the 11 × 1 extract. The concentrations of staurosporine quantified in the 11 × 1 extracts were in the range of the staurosporine minimum inhibitory concentrations for P. myriotylum, supporting the contribution of staurosporine to the biocontrol effect of 11 × 1. The use of 11 × 1 culture filtrate to control both ginger and soybean diseases could be beneficial in an intercropping system of ginger and the leguminous nitrogen-fixing soybean. [ABSTRACT FROM AUTHOR]

In Egypt, only two local cultivars are known, namely, Assiuty and Manfalouty. Pomegranate root rot disease causes significant losses and often goes undetected in the early stages. A better understanding of the pathogen that causes a disease is important for its control. The objective of this study is to select, and characterize new genotypes of Manfalouty and Assiuty pomegranate cultivars for their qualitative and quantitative characteristics and identify the root rot tolerance in pomegranate genotypes. Socary genotype almost surpasses all the tested genotypes in the vegetative growth. The results indicated that Manfalouty genotype showed the lowest symptoms of root rot with disease severity value (33%), while Socary genotype showed the highest disease severity (75%). The obtained results may be useful in planning phytosanitary strategies and for pomegranate breeders in selecting root rot-resistant cultivars and paving the way for breeding programs and germplasm management. [ABSTRACT FROM AUTHOR]

Common bean (Phaseolus vulgaris L.) is an important food legume crop and major protein source in Kenya and many parts of the world. However, the yields are low due to the diseases like anthracnose caused by Colletotrichum lindemunthianum and Pythium root rots. The study, therefore, sought to screen Kenyan common bean genotypes for anthracnose and Pythium resistance and to improve the resistance of local landraces to the two diseases. Local landraces and commercial cultivars were screened for resistance under greenhouse conditions for Pythium and in vitro for anthracnose. The results showed that majority of the landraces were moderately resistant to anthracnose and Pythium root rot. The study further utilized molecular markers linked to anthracnose and Pythium resistance, respectively, to determine their potential to detect specific resistance genes among the test genotypes. None of the markers amplified the test genotypes except the control genotypes pointing toward different resistance genes. Further, cultivars G2333 and KK8 were used as donor parents for anthracnose and Pythium resistance, respectively, in a marker-assisted backcross breeding program involving three high-yielding farmer-preferred landraces. A number of lines were developed that carry both resistance genes. These lines can be advanced for release as new cultivars to enhance common bean production in Kenya. [ABSTRACT FROM AUTHOR]

Drought is a major abiotic stress which affects the growth and yield of crops globally. The infection caused by Macrophomina phaseolina is a significant limiting factor in the Vigna radiata (mungbean) production inflicting up to 100% yield losses under dry and hot conditions. In the present study, two cultivars of mungbean viz. RMG-492 and IPM 02-14 were exposed to combined M. phaseolina infection and drought stress. The cultivar RMG-492 was relatively more tolerant to M. phaseolina infection than IPM 02-14. There was reduction in disease incidence in plants exposed to combined stress in both the cultivars. However, a remarkable decrease in root rot (13.33%) and crown rot (20%) was observed in "IPM 02-14." This could be accredited to a stronger defense response including increased antioxidant capacity and lignin deposition in dual stress treated plants. Moreover, differences were observed on comparing the stress response in leaves upon fungal infection under well-watered and water-deficit conditions. The salicylic acid played a significant role in fungal stress response. However, soluble sugar mediated regulation was prominent in combined stress. Therefore, it could be concluded that plants adopt distinct response strategies under combined stress which could be further exploited to produce multiple stress resistant crops. [ABSTRACT FROM AUTHOR]

Three native Trichoderma isolates, Trichoderma koningii (OP050066), Trichoderma harzianum (OP050067), and Trichoderma viride (OP050068) selected of fourteen different native Trichoderma spp. isolated from rhizosphere of healthy soybean fields in Al-Baha region (Baljurashi Province) Saudi Arabia, were evaluated in-Vitro and under greenhouse conditions against the soil-borne fungi Rhizoctonia solani (OQ345525), Fusarium solani (OQ345527) and Fusarium oxysporum (OQ345526) isolated from soybean plants in the same region. The three tested Trichoderma isolates significantly inhibiting the mycelial growth of the three selected pathogens R. solani, F. solani and F. oxysporum in-Vitro and reduced the percentages of pre- and post-emergence damping-off caused by the three tested pathogenic fungi with significant increase of the survived soybean plants under greenhouse conditions. Furthermore, activities of peroxidase, polyphenoloxidase and chitinase oxidative enzymes of the treated plants were increased over the untreated control. The obtained results revealed the possibility of using that native Trichoderma isolate of soybean root disease management. [ABSTRACT FROM AUTHOR]

A highly controlled environment inside the greenhouse could provide suitable temperatures, nutrients, and light intensity for the crops. However, Pythium root rot continually threatens the productivity of numerous kinds of crops in hydroponic systems, including tomato, poinsettia, spinach, lettuce, and rose. It is caused by Pythium aphanidermatum, which grows well in the warmer temperatures inside the green house and is able to survive in low temperatures as well. In this research, we studied 165 isolates of P. aphanidermatum collected from three prefectures in Japan. We developed 10 reliable microsatellite markers to evaluate the genetic diversity of P. aphanidermatum. In total, 34 multilocus genotypes (MLGs) were observed. The index of association suggested that the population was highly clonal. This result was supported by the low result of Fst (0.075) and the short genetic distance per locus visualized in the minimum spanning network. The clonal population suggested that asexual reproduction was dominant. [ABSTRACT FROM AUTHOR]

The most significant issue affecting balloon flower (Platycodon grandiflorus) in Vietnam's mountainous provinces is stem and root rot disease. The purpose of this study was to identify the causal fungus Fusarium solani of balloon flower planted in Lao Cai province. F. solani's identity was confirmed through DNA sequencing and phylogenetic analyses based on ITS sequences. PDA was the most suitable medium for F. solani growth and development of the three semi-solid media tested (CA, PDA, and CDA). The optimal temperature and pH conditions for its growth ranged from 25-30 °C with a maximum growth rate of 25 °C and pH 5.5-7.0 with a maximum growth rate of 6.5. This is the first report of F. solani causing balloon flower stem and root rot in Vietnam. [ABSTRACT FROM AUTHOR]

Elsinoë are plant pathogenic fungi that cause scabs, spotted anthracnose, and some morphological distortions on various plants, including woody plants, economically important crops, and ornamental plants. Taxonomical reexamination of Elsinoë species in Japan has not yet been conducted based on the modern species criteria. In this study, several Japanese isolates were reexamine based on the morphological and molecular-phylogenetic analysis of the internal transcribed spacer region (ITS), large subunit gene (LSU)m and protein-coding gene such as RNA polymerase II subunit (rpb2) and Translation elongation factor 1-alpha (tef). Japanese isolates were divided into four clades and three new species, Elsinoë hydrangeae, E. sumire, and E. tanashiensis were proposed. One species, Sphaceloma akebiae, was transferred to the genus Elsinoë. [ABSTRACT FROM AUTHOR]

Raspberry root rot and wilting complex (RRWC), primarily caused by Phytophthora rubi, is the most important disease for raspberry producers in Canada. There is currently little to no information on phenotypic diversity or sensitivity to metalaxyl-m of P. rubi isolates affecting raspberries in Canada. This study was conducted to understand the diversity in virulence and sensitivity to metalaxyl-m of P. rubi populations collected from diverse raspberry cultivars, fields, and locations during 2018–2020. All isolates of P. rubi (n = 24) were pathogenic on 'Chemainus' raspberry and showed significant variation (P < 0.05) in days to first foliar symptom development (DFSD) and progress in wilting index, as indicated by relative areas under disease progress curves (rAUDPC). Principal component analyses identified that root rot index, rAUDPC, DFSD, and percentage reduction in root length and weight were important variables in assessing pathogen virulence. Metalaxyl-m sensitivity was assessed using a radial growth assay and effective concentrations that inhibited 50% of mycelial growth (EC50) were determined for 44 isolates. The EC50 values ranged from 0.035–4.71 µg mL−1 with a mean value of 0.793 µg mL−1. About 61% of the isolates were very sensitive (EC50 values <0.20 µg mL−1), 25% of isolates were considered sensitive (EC50 values of 0.21–1.18 µg mL−1), and 14% of isolates showed reduced sensitivity to metalaxyl-m (EC50 value range of 1.19–4.71 µg mL−1). Knowledge of pathogen phenotypic diversity will be useful for raspberry breeders in screening genotypes against RRWC and the results of the fungicide sensitivity study will be useful in developing management strategies for RRWC. [ABSTRACT FROM AUTHOR]

Damping-off, crown rot, and root rot caused by Fusarium oxysporum and Pythium spp. are important diseases that reduce the growth of cannabis plants and cause mortality. There are currently limited management options available to producers in the absence of registered chemical fungicides. The comparative efficacy of five biological-control agents in reducing disease severity was evaluated in this study. Rhapsody® ASO (Bacillus subtilis), Stargus® (Bacillus amyloliquefaciens), Lalstop® (Gliocladium catenulatum, Prestop®), RootShield® Plus WP (Trichoderma harzianum and Trichoderma virens), and Asperello® (Trichoderma asperellum) were applied to cannabis cuttings in rockwool blocks followed 48 hr later by inoculation with a F. oxysporum spore and mycelial suspension. Disease was rated 7, 14 and 21 days post-inoculation. The most effective treatments were Lalstop, Rootshield, Asperello and Stargus, which provided a significant (P < 0.05) reduction (30 to 56.3%) in mean disease severity 14 days post-inoculation compared to the Fusarium inoculated control. Application of Rootshield, Asperello and Lalstop resulted in endophytic colonization of cannabis cuttings when assessed after 2 and 7 days. For Pythium biocontrol, Rootshield Plus WP, Asperello, and Lalstop were applied as a drench to rooted plants 7 days before inoculation with P. myriotylum. Based on disease severity ratings and plant measurements in two experiments, the most effective treatments were Rootshield and Lalstop. Plants receiving Lalstop or Rootshield had significantly (P < 0.05) higher fresh root weights compared to the pathogen only treatment. These results indicate that several biological control agents can protect cannabis plants from infection by Fusarium and Pythium spp. through pre-emptive colonization. [ABSTRACT FROM AUTHOR]

Plant disease management in agriculture science is the primary concern for every country, as the food demand is increasing fast due to an increase in population. Furthermore, modern technology has improved the efficacy and precision of disease detection in plants and animals. Plant disease identification using various image processing approaches has recently been employed on a big scale to help farmers monitor their plantation areas. Based on the perpetuation and spread, the diseases can be floral, foliar, and soilborne. Grain production is typically affected by foliar diseases, which reduce photosynthetic area, duration, and function. Soil-borne conditions include vascular wilt, root rot, and damping-off; and can exhibit symptoms such as wilting of foliage, root decay, and sudden death. This paper highlights the significant issues and challenges for leaf disease classification. A comparative study of different methods based on the agricultural product, methodology, efficiency, advantages, and disadvantages is also included. The review study analyzes the most frequently used machine learning algorithms in the last five to seven years, revealing that Support Vector Machine (SVM) has been extensively used for disease classification. An analysis of specific Techniques (Feature Extraction plus machine learning-based Classification algorithm) and their associated accuracy is also performed, demonstrating that (ORB) features combined with Linear SVM provide the highest accuracy of 99.98%. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Armillaria fungi are frequently documented as economically and ecologically significant plant pathogens, recognised as the causal agents of Armillaria root rot disease. Armillaria mellea is one of the most aggressive pathogens in the Armillaria genus. None of the chemicals tested against Armillaria have been effective in fully eradicating an established A. mellea mycelium from an infection site and/or preventing plant mortality, which makes studies about the chemical sensitivity of A. mellea essential. In this work, the inhibitory effects of 120 different chemical agents on the growth rate of A. mellea were examined using the Biolog Phenotype MicroArray system of chemical sensitivity panels. Among the tested substances, aromatic and membrane function compounds showed the highest inhibitory activity against A. mellea. Interestingly, our results demonstrated promising potential for application of caffeine as an A. mellea-oriented fungicide. Further studies were conducted to explore the antifungal activity of a low-cost and locally available caffeine-rich waste, i.e. spent coffee grounds (SCG) against A. mellea. It is noteworthy that the hyphal growth of A. mellea was significantly inhibited when cultivated on malt extract agar supplemented with SCG. Current findings uncovered, for the first time, the potential use of caffeine-rich wastes for designing management strategies to practically control the spread of A. mellea. [ABSTRACT FROM AUTHOR]

Hedychium coronarium Koen is a perennial flowering plant that has ornamental, nutritional and medicinal value. In October 2019, root rot symptoms were observed in fields of H. coronarium in Yunnan Province, China. Fungal isolates were obtained from the diseased samples and the pathogenicity was confirmed by fulfilling Koch's postulates using wounded and unwounded plant inoculations. The pathogen was identified as Ceratobasidium sp. (binucleate Rhizoctonia) through morphological characterization and anastomosis grouping as well as sequence analysis of both rDNA-ITS and EF-1α. To our knowledge, this is the first report of Ceratobasidium sp. AG-I (binucleate Rhizoctonia) causing root rot on H. coronarium. [ABSTRACT FROM AUTHOR]

Severe root rot was observed in onion seedlings growing in nursery seedbeds in Changnyeong, South Korea in September 2021. The diseased onion seedlings showed symptoms including water-soaking, browning and blight, followed by seedling collapse. Three isolates were obtained from diseased onion seedlings, and their morphological characteristics were found to be similar to previously described Pythium species. Artificial inoculation with isolates produced identical symptoms to those observed in the original infection. Based on morphological characteristics, sequencing of rRNA gene internal transcribed spacer, ribosomal large subunit gene region, and cytochrome c oxidase subunit I gene region, and pathogenicity testing, the causative agent of root rot on the onion seedlings was identified as Globisporangium irregulare (formerly Pythium irregulare). This is the first report of root rot caused by G. irregulare on onion seedlings in Korea. The results of this study suggest that root rot may pose a severe threat to onion seedling cultivation. [ABSTRACT FROM AUTHOR]

Since 2015, necrosis caused by Fusarium spp. has been regularly observed in carrot seed crops in France. A collection of 53 Fusarium isolates was gathered from lesions on carrot between 2016 and 2019. Morphological characterization at both the macroscopic and microscopic levels and molecular typing based on the ACL1, RPB2 and EF1-α partial gene sequences resulted in the identification of two main groups, corresponding to 22 F. avenaceum and 22 F. tricinctum isolates. In addition, three isolates of F. graminearum, two each of F. oxysporum and F. acuminatum, and one isolate of F. solani were also identified. Dual cultures of Trichoderma spp. (T. atroviride and T. harzianum) and Fusarium spp. (F. tricinctum isolate FT001 and F. avenaceum isolate FA002) did not indicate any antibiosis capabilities of Trichoderma. The in vitro sensitivity of isolates FT001 and FA002 to two fungicides and one natural product was similar, with an efficacy depending on the active ingredient. Prothioconazole + tebuconazole was more effective (mycelial growth reduced by 97% for FT001 and 99.8% for FA002) than fluopyram + trifloxystrobin (mycelial growth reduced by 58% and 56%, respectively). Allium extracts seemed to be a promising alternative to fungicides, since they were almost as efficient as prothioconazole + tebuconazole. Artificial inoculation of durum wheat using three isolates from carrot lesions (FT001, FA002 and F. graminearum FG001) induced plant necrosis. This result suggests that Fusarium pathogens of carrot seed crops may be transmitted to wheat, which is commonly used in rotation with carrot. [ABSTRACT FROM AUTHOR]

I Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada (AAFC), 5403 1st Avenue South, Lethbridge, AB T1J 4B1, Canada; and (A.B.) Morden Research and Development Centre, AAFC, 101 Route 100 #100, Morden, MB R6M 1Y5, Canada i Stripe rust disease caused by the pathogen I Puccinia striiformis i f.sp. At present, the disease is managed mainly by planting clubroot-resistant canola cultivars, which initially became available in 2009 and 2010. B Screening of barley cultivars for resistance to I Bipolaris sorokiniana i isolates from the Prairies. b D. D. ADIHETTY, K. XI, H. KLEIN-GEBBINCK, R. ABOUKHADDOUR, H. R. KUTCHER, J. R. TUCKER, X. WANG, W. XU, A. D. BEATTIE, A. BADEA, T. K. TURKINGTON AND S. E. STRELKOV. B Transcriptome analysis of rutabaga ( I Brassica napus i ) cultivars indicates glucosinolate-derived nitriles may play a role in inducing plant defence against clubroot disease. b H. LIU, Q. Q. ZHOU, S. E. STRELKOV, S. F. HWANG AND J. A. OZGA. [Extracted from the article]

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. [ABSTRACT FROM AUTHOR]

Bipolaris sorokiniana root-rot of wheat seedlings remains a serious worldwide problem. Spores of Nocardiopsis albirubida strain NA2 were bioformulated as talcum wettable powder (TWP) and clay-alginate pellets (CP) biofungicides before screening for their biocontrol effect. Based on their promising biocontrol results, the talcum powder biofungicide was selected to optimise the bioformulation parameters using the response surface methodology (RSM). The biofungicides TWP and CP significantly (P < 0.05) and respectively reduced the disease severity index (DSI) to 25.6% and 58.2% compared to a positive control (84.0%). Furthermore, the talcum powder biofungicide showed no significant differences compared to a marketed chemical control agent (Difenoconazole®). The TWP biofungicide was selected and a Placket-Burman screening design was explored to evaluate the composition for an optimised biofungicide. Two variables: washed spore density and talcum powder quantity, respectively, showed an important in planta biocontrol effect on B. sorokiniana. The RSM optimisation for the two influencing variables allowed a very notable reduction of the DSI, passing from 25.6% (standard formulation process) to 5.1% (optimised talcum powder biofungicide) by using 25 ml of washed spore suspension (≈107spores ml−1) and 125 g of autoclaved talcum powder. The coefficient of determination R2 = 0.950 indicated that 95.0% of the response variability can be simulated with the suggested mathematical equation. The spore viability and the biocontrol efficacy have been demonstrated after 12 months storage. The TWP biofungicide based on washed NA2 spores open up promising applications for the biocontrol of B. sorokiniana root rot. [ABSTRACT FROM AUTHOR]

Multilocational field studies were conducted near North Battleford, Wilkie and Cando in Saskatchewan (SK), Canada during the 2015 (year 1) and 2016 (year 2) summer crop growing seasons to evaluate Aphanomyces euteiches Drechs and Fusarium root rot response to different seed place fertility, preemergence herbicide combination, and foliar fertility. Seven seed place fertility treatments (F1 to F7) were Nitrogen and phosphorus inoculant, liquid Optimize inoculant (LCO), LCO /5.5-25-0-0 (N-P-K-S), LCO /15-25-0-0, LCO /15-25-0-15, LCO/liquid orthophosphate (2-8-1) at 33.7 L/ha/15-0-0-15 and LCO/15-40-40-15 respectively. The four preemergence herbicide (P RE1 to P RE4) were: Glyphosate/Saflufenacil; Glyphosate/Sulfentrazone/Carfentrazone; Glyphosate/Sulfentrazone/Pyroxasulfone and Glyphosate/Sulfentrazone/Trifluralin. Pea was treated with five postemergence (POST 1-5) herbicide with/without adjuvants/foliar fertility at 4-5 node stage as Imazamox/bentazon (Viper) plus 28% v/v Urea Ammonium Nitrate (UAN) – POST 1; Viper plus 2X 28% UAN – POST 2; Viper plus 1X 28% UAN plus foliar fertility – POST 3; Viper plus 2X 28% UAN plus foliar fertility – POST 4 and Quizalofop-p-ethyl at 494.23 mL/ha – POST 5. Growth response, root rot disease severity and yield (kg/ha) were analyzed using SAS statistical software. Significant means were at F < 0.05 were separated by the Fisher's Protected LSD test at the 5% level. Root rot was significantly lower in P RE4 compared to other treatments. Postemergence herbicide treatments and seed-place fertility recorded significant interaction on root rot incidence and yield. There was over 30% yield improvement between 2016 and 2015 trials due to soil moisture. The trial minimized pea root rot from infested soils and increased yield. [ABSTRACT FROM AUTHOR]

Biocontrol, an alternative to chemical control against plant pathogens, may also improve plant health and enhance fruit yield. Tomato production in open fields or greenhouses is constrained by the pathogens Fusarium oxysporum f. sp. lycopersici race 3 (Fol R3) and F. oxysporum f. sp. radicis-lycopersici (Forl). In this work, we studied the biocontrol effect of the antagonistic bacteria Acinetobacter calcoaceticus AcDB3, Bacillus thuringiensis BtMB9, B. subtilis BsTA16, and B. amyloliquefaciens BaMA26 in field trials with four tomato hybrids over two consecutive growing seasons (2019–2020 and 2020–2021). The effect of these bacteria on plant growth was also evaluated. The presence of F. oxysporum in field soil and/or infected plants was confirmed microbiologically. All four bacterial strains significantly suppressed the severity of Fusarium crown and root rot of tomato (FCRRT) and Fusarium wilt symptoms, as well as increased tomato yield under field conditions. Among the four strains, B. subtilis BsTA16 showed the highest reduction in symptoms of Fusarium wilt (68%) and FCRRT (74%). To the best of our knowledge, this is the first report of biological control agents (BCAs) exerting antagonistic activity against both FCRRT caused by Forl and Fusarium wilt caused by Fol in tomato under field conditions. [ABSTRACT FROM AUTHOR]

Root chicory (Cichorium intybus var. sativum) production is increasing in KwaZulu-Natal Province, South Africa, especially on coarse-textured soils, prone to boron (B) deficiency. Literature on the response of chicory to B application is scarce and largely anecdotal. A field experiment was conducted to determine this response and the movement of B in the upper 60 cm of a loamy sand. Eight rates of B (from 0 to 3.5 kg ha−1) were either soil- or foliar-applied, with four replications. Soil samples were taken pretrial and after each of the two harvests at 15 cm depth intervals to 60 cm for fertility analysis. Hot water soluble B was also analyzed. Results are presented as means of the two harvest periods for yield, and leaf and soil analysis. Root analysis is reported for the second harvest only. Yield effects were not significant (p > 0.05) for both seasons over all B application rates. Application method (App), and the App × B interaction were also not significant. Root chicory was tolerant to 3.5 kg B ha−1. Multiple rooting, especially in the control plots, was significant compared to plots that received B and root rot incidence was also significantly higher, probably due to B deficiency. Root quality was compromised at about 0.1 mg B kg−1 in the topsoil. A highly significant movement of B occurred from the topsoil to 45–60 cm measured after the final harvest. The application rate, App, and time were all significant for the averaged data from the 0–15 to 45–60 cm depths. [ABSTRACT FROM AUTHOR]

Fusarium verticillioides (Fv) is a mycotoxin-producing phytopathogen causing ear and root rot in maize. Bacillus cereus strain B25 is a maize endophyte and an effective biological control agent against Fv. The B25 genome contains several genes associated with fungal antagonism, including lytic enzymes (chitinases A and B, chitosanase and glycoside hydrolase), siderophores (petrobactin and bacillibactin), antibiotics (surfactin), and biofilm. This study aimed to elucidate which B25 antagonistic mechanisms are implicated in Fv biocontrol. The expression of twelve B25 genes was evaluated by qRT-PCR after 3–30 h of confrontation between B25 and Fv. All B25 genes tested were induced, mainly between 6 and 24 h, while none was induced at 3 h. Lytic enzyme genes were induced at different times, with three of them occurring at 12 h. Chitinase and chitosanase activities were induced after 6 and 12 h, respectively, and gradually increased until 30 h. Biofilm formation was detected only when B25 interacted with Fv. Images of the B25-Fv interaction and measurements at 24 and 30 h showed little branching or abnormal mycelial growth, suggesting cell wall damage. In conclusion, when B25 is confronted against Fv, all B25 antagonistic mechanisms tested appear to be involved in Fv growth control. [ABSTRACT FROM AUTHOR]

Cyclamen (Cyclamen persicum Mill.) is an ornamental plant affected by various phytosanitary issues including bacterial soft rots, which cause crop losses of 20% worldwide. In Colombia, however, the symptoms of bacterial soft rots are not well described and the causal agents are unknown. This study aimed to characterize the bacterial soft rot disease according to its symptoms, and identify its causal agents at the species level. For this purpose, we visited nurseries in the municipality of San Antonio del Tequendama, Colombia, and selected diseased plants to describe symptoms, and to isolate and characterize pathogens using morphological, biochemical, and molecular methods. Soft rotting activity in potato tubers and pathogenicity in cyclamen plants also was evaluated. Six symptoms were found to be associated with the disease, namely: wilt, soft corm, bacterial exudates on corms, root rot, soft rot and necrotic soft rot on petioles and peduncles. Of 47 isolates, seven were pathogenic: one from the soft corms; two from petioles with soft rot; two from petioles with necrotic soft rot; and two from root rot. A multiple correspondence analysis clustered isolates in the genera Pseudomonas, Dickeya and Pectobacterium based on the morphological, biochemical, and pathogenic characteristics. A multi-locus analysis (MLSA) based on sequencing of the 16S rDNA region and housekeeping genes (gapA, icdA, mdh, pgi, rpoB and rpoD) confirmed the bacterial species Pseudomonas asplenii, Dickeya solani and Pectobacterium atrosepticum as the causal agents of cyclamen bacterial soft rot in Colombia. [ABSTRACT FROM AUTHOR]

Effects of cultivar, herbicide and sowing date on bean fly, Fusarium root rot, weed and productivity were examined during 2015 and 2016 seasons using a split-split-plot design. Sowing delayed from 10-15 May (mid spring) to 25–30 June (early summer) reduced weed biomass up to 49% (2015) and 78% (2016) at flowering, and 79% at maturity in control plots. Herbicides decreased weed biomass up to 79% (2015) and 63% (2016) for first-date sowings of COS16 and Talash cultivars at maturity compared to control. Late June sowings decreased disease incidence up to 75% at maturity. Late sowings indicated greater fly infestation and shorter bean plants compared to earlier sowings. Low 100-seed weight and yield (kg/ha) of bean cultivars were obtained for early sowings. This research advised late sowing of beans in late spring to minimize Fusarium root rot, herbicide applications and weed threats, and improve 100-seed weight and yield for sustainable production. [ABSTRACT FROM AUTHOR]

The efficacy of Trichoderma asperellum (TNAU-Tv) and Pseudomonas fluorescens (TNAU-Pf1) as seed treatment and soil application along with Farmyard Manure against groundnut root rot disease was evaluated under rainfed condition during the years 2016, 2017 and 2018. During the study, the results showed that among the various treatments imposed, seed treatment with Pseudomonas fluorescens10g/kg, Trichoderma asperellum 4 g/kg recorded maximum reduction of root rot incidence over control. Further, the soil applications of biocontrol agents Trichoderma asperellum 2.5 kg + FYM @ 200 kg/ha and 2.5 kg Pseudomonas fluorescens + FYM@ 200 kg/decreases the soil-borne diseases of root rot (80.67) and (79.27)% reduction over control and also recorded higher yield of 1176 kg/ha with simultaneous increase in seedling stands, plant height, and fresh weight, compared with untreated and chemical checks. In addition, BioVis PSM Root – Rhizoscanner study results in root length (361 mm), root tips (35Nos), forks (43Nos) segments (46) and estimated volume (452 cm3) in T. asperellum and P. fluorescens seed treatment. [ABSTRACT FROM AUTHOR]

Red raspberry (Rubus idaeus L.) is an important fruit crop in British Columbia, Canada, and the Pacific Northwest (PNW) region of the USA, as well as in other regions of the world. Root rot and wilting complex (RRWC), primarily caused by Phytophthora rubi, is the most important biotic constraint responsible for declining raspberry production in these regions, causing millions of dollars in losses. Other root-infecting fungal species and the root lesion nematode (Pratylenchus penetrans) may also be found associated with the disease complex. The average lifespan of raspberry plantings in the PNW is 10 to 12 years, which is reduced to 5 years by the disease complex. Phytophthora spp. play a predominant role in the RRWC complex due to the persistent nature of oospores, rapid dispersal of inoculum, and the polycyclic nature of infection, all of which increase disease severity. In this review, we discuss the current understanding of Phytophthora spp. and other pathogens associated with the RRWC, including pathogen biology and the disease cycle, the impact of infection on the plant, as well as current and potential cultural, biological, and chemical options for management. In addition, we discuss breeding efforts for disease resistance, including conventional and molecular approaches to identify sources of resistance, molecular markers linked to potential resistance genes, and their incorporation into elite breeding materials or cultivars. We also present the current gaps in knowledge, unique challenges, and future perspectives in sustainable disease management of this important disease complex. [ABSTRACT FROM AUTHOR]

Bakanae disease has been a major problem in rice production throughout the world. The most common and virulent species is Fusarium fujikuroi. The high genetic variability and epidemic character of Fusarium fujikuroi causes very important problems control of the disease. The use of resistant varieties is preferred in many countries of the World. This study aimed at the reactions of both Turkish and Italian cultivars to Bakanae disease, which are the most cultivated in Turkey and preferred by farmers. The most observed symptoms were that afflicted plants were taller than the normal height, thin and yellowish-green, there was browning of the leaves in the progressing period, rot in the root and root collar. All the tested rice cultivars in the study were found susceptible to the disease. This shows that Turkish and Italian rice varieties, which are most preferred in the Turkish rice market, are extremely susceptible to this disease. [ABSTRACT FROM AUTHOR]

Nineteen chickpea isolates of R. bataticola were obtained from different locations of Turkey in 2016–2017. The isolates were examined for their morphology, genetic and virulence characteristics. The colony color of 10 isolates was grayish black and rest of them was black. Eleven isolates had appressed colony texture, while 3 isolates had velvety and 5 isolates had fluffy. Eight isolates produced aerial mycelium and the other did not. Eight isolates were categorized as fast growing, 8 isolates were categorized as medium growing and 3 isolates were categorized as slow growing. The mean sclerotial sizes of the isolates varied between 65.6 and 127.4 µm. The sclerotia of the 11 isolates were round, 3 isolates were ovoid and 5 isolates were irregular shaped. The size of the PCR products varied from 435 to 518bp and the isolates showed between 99.61 and 100% identity with the reference. The isolates were highly variable in their morphological, molecular and virulence characteristics. [ABSTRACT FROM AUTHOR]

Cannabis (Cannabis sativa L., marijuana) plants with symptoms of crown rot, root decay, wilting and plant death were sampled during 2018 and 2019 from seven licensed production greenhouses. Affected tissues from 140 diseased plants were surface-sterilized and plated onto potato dextrose agar. Ninety-five isolates morphologically resembling Pythium species were subcultured and subjected to PCR of the ITS1-5.8-ITS2 region of ribosomal DNA. The following species were identified based on >99% sequence identity to reference isolates in GenBank: P. myriotylum (43 isolates), P. dissotocum (35 isolates), P. aphanidermatum (3 isolates) and Globisporangium ultimum (syn. P. ultimum) (2 isolates). A fifth species – P. catenulatum (12 isolates), was distinguished from P. rhizo-oryzae using the cytochrome oxidase c subunit I (COI) sequence. Cannabis licensed production facilities in British Columbia had all five species present, while P. dissotocum was found in two facilities in Ontario, and P. myriotylum was present in one facility in northern California. Isolates selected to represent each Pythium species were grown on potato dextrose agar at 25°C and they all showed comparable colony growth after 6 days. The same isolates caused root browning, decay and stunting of cannabis plants grown in a coco: perlite potting medium. Plant mortality was similar after 21 days but rates of disease progression varied depending on the isolate tested. Wounding of roots and prolonged periods of saturation enhanced disease development. These results demonstrate for the first time that crown and root rot on greenhouse-grown cannabis plants can be caused by up to five Pythium species. [ABSTRACT FROM AUTHOR]

Root rot disease of cassava is one of the major diseases in Thailand, widespread incidence of soil-borne pathogens has been found to affect more than 80%. The research aims to investigate the effect of elicitors as salicylic acid and Bacillus subtilis strain JN2-007 for inducing resistance against root rot disease by Fusarium solani in cassava. The experiment was carried out in a susceptible cassava cultivar to test the efficacy of elicitors in the biochemical response of plant defense mechanisms pertaining to hydrogen peroxide (H2O2) and enzyme activities. The results indicated that pathogenicity test of F. solani isolate SHRD1 caused the brown lesions around the inoculation point on cassava roots. Subsequently, salicylic acid and JN2-007 reduced mycelial growth of F. solani (11.83%–57.73% at day 7), as well as disease severity in the cassava plants at 14 days after the inoculation compared to that of the negative control (28.12%–39.58% compared to 68.75%). Furthermore, salicylic acid at a concentration of 500 µl. L−1 could induce H2O2, level of peroxidase, polyphenol oxidase, and catalase activities that were highest at 24 h after pathogen inoculation. The results suggested that elicitors played an important role as a plant defense inducer, leading to reduced Fusarium root rot disease. [ABSTRACT FROM AUTHOR]

Peanut [Arachis hypogea (L.)] is a valuable legume crop that is widely cultivated in Northern Nigeria. The yield of this crop is affected by root rot disease caused by the fungal pathogen (Macrophomina phaseolina). This study was carried out to assess the efficacy of Zinc (Zn) (1.76, 3.59, 4.71 and 6 mg kg−1) and Manure [M (2% and 4%)] in a complex interaction to manage the disease and improve yield. Two genotypes of peanut were selected for this study on the basis of their susceptibility to M. phaseolina (severely infected UGA 2) and (moderately infected ICGV 86015). The results showed that M. phaseolina suppressed the plant defense action through the activities of malionaldehyde (MDA), superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) thereby hindering identification of the pathogen elicitor. It was observed that manure enhanced the microbial activity and physicochemical properties of soil, which induced plant defense and antimicrobial protein against reactive oxygen species (ROS) thereby reducing the susceptibility of the pathogen to the peanut plant. The co-factor ability of Zn enhanced the activities of antioxidant enzymes to scavenge ROS molecules in the pathogen stressed cells, improve photosynthetic efficiency and prevent the plant from death. Therefore, this study has revealed that Zn and manure inhibits the multiplication of M. phaseolina in the peanut seedlings. [ABSTRACT FROM AUTHOR]

Crown and root rot of wheat is considered as one of the most damaging diseases, resulting in significant yield losses in different regions worldwide. The aim of this study was to isolate and identify Fusarium species associated with crown rot of wheat in Syrian coastal areas. Ten Fusarium isolates were recovered from crowns and roots of durum wheat plants (var. Cham5), showing typical symptoms, collected from five different sites in coastal Tartous province. Based on morphological characteristics, 7 isolates were identified as F. incarnatum (syn. F. semitectum), and 3 isolates were F. solani. The sequencing of a partial TEF1-α gene of two representative isolates of these two species confirmed the morphological identification. Phylogenetic tree of partial TEF1-α gene showed a clear separation between the two species and high genetic similarity of Syrian and reference isolates. Up to our knowledge, this is the first report of F. incarnatum and F. solani infecting the roots and crowns of wheat in Syria. [ABSTRACT FROM AUTHOR]

A 2-year research was conducted to evaluate the effects of bean cultivar, herbicide and planting date on a plot scale in Zanjan Province, Iran. Weeds across plots were identified as 26 species. Weed density was often lower for the fourth planting date (25-30 June) than the first date (10-15 May) of Imazethapyr, Trifluralin, hand-weeding and control at seedling, flowering and maturity stages of bean growth. At seedling and flowering, there was a greater Rhizoctonia root rot incidence on the first planting date than the fourth date. Postponing cultivation to the fourth planting date decreased mean disease incidence up to 93% at flowering in 2014 and 75% at maturity in 2015. There were greater mean fly infestation ratings at the third (2014) and fourth (2015) planting dates of treatments. Fly infestation was lacking in beans planted at the second date of cultivar and herbicide treatments examined in 2015. Postponing planting from the first date to the fourth one increased mean plant dry matter up to 162% at flowering in 2015. The highest number of pods per plant and seeds per pod were recorded for the third (2014) and first-second (2015) planting dates. This study recommends a postponed planting to minimize disease, herbicide use and weed threats, and thus produce beans in sustainable agriculture. [ABSTRACT FROM AUTHOR]

Fusarium species are generally appropriated pathogens in roots, plant debris and soil causing major disease as primary, secondary invader and co-invader with other pathogens. Fusarium chlamydosporum is the second most important pathogen, followed by F. solani to cause root rot disease in soybean (Glycine max) crop. The present study explores mycoparasitic activity of Pseudomonas aeruginosa (OG101) and Pseudomonas putida (PP) for the management of Fusarium infection in soybean crop. Investigation of glucanase production, chitinase production as well as effect on spore germination was assessed for in vitro biocontrol activity of Pseudomonas sp. and obtained that P. aeruginosa (OG101) produced 13% higher glucanase, 12% higher chitinase and 15% more spore inhibition as compared to P. putida (PP). Disease index of 1.73 and 2 was observed in plants treated with P. aeruginosa (OG101) and P. putida (PP) in presence of pathogen F. chlamydosporum, respectively. Both strains exhibited mycoparasitic activity which helps in management of fusarial infection in Glycine max. [ABSTRACT FROM AUTHOR]

Root rot is an important disease of the medicinal plant Atractylodes macrocephala (bai zhu) in China. This study evaluates an antagonistic fungal agent, Trichoderma brevicompactum, as an alternative to chemical pesticides for control of root rot caused by Fusarium oxysporum. The inhibitory effect of T. brevicompactum on F. oxysporum was examined in dual-culture experiments, with mycelial growth of the pathogen found to be reduced by 74.4%. The results of an enzyme-linked immunosorbent assayindicated that T. brevicompactum produced enzymes such as cellulase and chitinase, suggesting that the fungal agent may inhibit F. oxysporum growth by producing cell wall hydrolases. Under greenhouse conditions, the efficacy of T. brevicompactum was evaluated based on its effects on root rot severity, plant height, root dry weight, and root fresh weight. When used as a soil treatment, T. brevicompactum reduced root rot severity by 48% to 58% and increased plant growth and biomass significantly when compared with the control (healthy) group. The plant growth-promoting effect of T. brevicompactum seems related to its production of secondary metabolites that contain an auxin (indoleacetic acid), and to the disease resistance induced in the host by the fungal agent. The results of this study suggest that T. brevicompactum not only controls root rot in A. macrocephala but may also promote growth of the plant. [ABSTRACT FROM AUTHOR]

Chickpea (Cicer arietinum L.) is an important food legume worldwide, providing a source of high-quality protein. Fifteen chickpea samples showing leaf yellowing and root rot were obtained from southern Alberta, Canada, in 2018. Twenty single-spore Fusarium isolates were obtained from those samples. Based on the morphological characteristics, five species of Fusarium were identified, with F. redolens as the predominant species (11 isolates), followed by F. culmorum (3), F. sporotrichioides (3), F. oxysporum (2) and F. equiseti (1). The identification of each isolate was confirmed using partial sequences of the translation elongation factor 1-alpha (EF-1α) gene. Each EF-1α sequence displayed 99.54% to 100% similarity to sequences for each corresponding species in the GenBank database. The Fusarium isolates were tested for pathogenicity on chickpea 'CDC Frontier' in a greenhouse. Isolates recovered from inoculated plants were confirmed as the respective Fusarium species, fulfiling Koch's postulates. Selected isolates of each Fusarium species were able to infect common crops including barley, corn, canola, and lentil in Alberta. This is the first report of F. redolens on chickpea in Alberta, F. equiseti on chickpea in Canada, and F. culmorum and F. sporotrichioides on chickpea in the world. [ABSTRACT FROM AUTHOR]

Pythium spp. are the most common pathogens associated with soybean damping-off in the United States. The diversity of Pythium spp. recovered is extensive and the relative pathogenicity or aggressiveness of species common across states has varied among studies. We compared the aggressiveness and fungicide sensitivity of 118 isolates of four Pythium spp. (P. lutarium, P. oopapillum, P. sylvaticum, and P. torulosum) from 11 states (AR, IA, IL, IN, KS, MI, MN, ND, NE, SD, and WI). All isolates were screened using seed and seedling assays at two temperatures (13°C and 23°C). Seed rot and root rot severity varied by state of origin, with isolates from AR always the most aggressive. In general, isolates of P. sylvaticum and P. lutarium were more aggressive at 23°C compared with 13°C, while isolates of P. oopapillum and P. torulosum were more aggressive at 13°C than at 23°C. Fungicide sensitivity to five fungicides (metalaxyl, azoxystrobin, ethaboxam, captan, and thiram) was assessed using a plate assay at 13°C and 23°C. The EC50 values for each fungicide-isolate combination varied by state of origin, and were greatest for the isolates from AR. Temperature affected EC50 values for metalaxyl, azoxystrobin, and ethaboxam for P. oopapillum, P. sylvaticum, and P torulosum. The EC50 values for thiram were not affected by temperature for any species. Results from this study indicate that aggressiveness and fungicide sensitivity of Pythium spp. vary geographically, which suggests that management of damping-off of soybean should target local rather than regional Pythium populations. [ABSTRACT FROM AUTHOR]

Phytophthora root and stem rot due to Phytophthora sojae is a major constraint of soybean production. This study evaluated the combined effect of P. sojae inoculation and flooding on growth of soybean seedlings. The soybean cultivar 'Enrei' was grown in a greenhouse in pots containing vermiculite and containers of field soil. The plants were inoculated with two P. sojae isolates and subjected to flooding. The ratio of dead to live plants ranged from 0 to 0.32 across all treatments. Pathogen inoculation caused a significantly shorter maximum root length (MRL) in all the three experiments. MRL and shoot and root dry weight were affected by interaction between inoculation and flooding in one experiment with vermiculite media. Flooding affected the growth parameters only in the experiment with soil media. The results indicated that root of the soybean seedlings that survived from P. sojae infection grew less well than the non-inoculated plants. [ABSTRACT FROM AUTHOR]

The current investigation deals with the isolation, identification and testing the antagonistic ability of Trichoderma spp. on Macrophomina phaseolina under in vitro and in vivo conditions. The locally isolated biocontrol agents were subjected to morphological and molecular identification and further research was carried out to test all the biocontrol agents. T. harzianum was found to be highly effective in dual confrontation test, restricting the fungal growth by 67.59% as compared to control. Various secondary metabolites of Trichoderma spp. were studied with inverted plate and culture filtrate assay. Mycoparasitism and antibiosis were also examined using light and Scanning Electron Microscopy (SEM) which indicated that all the Trichoderma spp. restricted the growth by coiling around the host hyphae and through secondary metabolites. In vivo experiments showed that all the treatments significantly reduced the disease severity and intensity where T. harzianum was found to be the most effective biocontrol agent (decreased upto 72.88 and 60.24%). Nevertheless, T. harzianum could be used as a potent indigenous biocontrol agent against dry root rot which also helped to reduce its deleterious effect on the host plant. [ABSTRACT FROM AUTHOR]