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Showing papers on "Leaf spot published in 2020"


Journal ArticleDOI
Jun Liu1, Xuewei Wang1
TL;DR: This study proposes an early recognition method of tomato leaf spot based on MobileNetv2-YOLOv3 model that improves the accuracy of the regression box of tomato gray leaf spot recognition by introducing the GIoU bounding box regression loss function.
Abstract: Tomato gray leaf spot is a worldwide disease, especially in warm and humid areas. The continuous expansion of greenhouse tomato cultivation area and the frequent introduction of foreign varieties in recent years have increased the severity of the epidemic hazards of this disease in some tomato planting bases annually. This disease is a newly developed one. Thus, farmers generally lack prevention and control experience and measures in production; the disease is often misdiagnosed or not prevented and controlled timely; this condition results in tomato production reduction or crop failure, which causes severe economic losses to farmers. Therefore, tomato gray leaf spot disease should be identified in the early stage, which will be important in avoiding or reducing the economic loss caused by the disease. The advent of the era of big data has facilitated the use of machine learning method in disease identification. Therefore, deep learning method is proposed to realise the early recognition of tomato gray leaf spot. Tomato growers need to develop the app of image detection mobile terminal of tomato gray leaf spot disease to realise real-time detection of this disease. This study proposes an early recognition method of tomato leaf spot based on MobileNetv2-YOLOv3 model to achieve a good balance between the accuracy and real-time detection of tomato gray leaf spot. This method improves the accuracy of the regression box of tomato gray leaf spot recognition by introducing the GIoU bounding box regression loss function. A MobileNetv2-YOLOv3 lightweight network model, which uses MobileNetv2 as the backbone network of the model, is proposed to facilitate the migration to the mobile terminal. The pre-training method combining mixup training and transfer learning is used to improve the generalisation ability of the model. The images captured under four different conditions are statistically analysed. The recognition effect of the models is evaluated by the F1 score and the AP value, and the experiment is compared with Faster-RCNN and SSD models. Experimental results show that the recognition effect of the proposed model is significantly improved. In the test dataset of images captured under the background of sufficient light without leaf shelter, the F1 score and AP value are 94.13% and 92.53%, and the average IOU value is 89.92%. In all the test sets, the F1 score and AP value are 93.24% and 91.32%, and the average IOU value is 86.98%. The object detection speed can reach 246 frames/s on GPU, the extrapolation speed for a single 416 × 416 picture is 16.9 ms, the detection speed on CPU can reach 22 frames/s, the extrapolation speed is 80.9 ms and the memory occupied by the model is 28 MB. The proposed recognition method has the advantages of low memory consumption, high recognition accuracy and fast recognition speed. This method is a new solution for the early prediction of tomato leaf spot and a new idea for the intelligent diagnosis of tomato leaf spot.

109 citations


Proceedings ArticleDOI
07 Oct 2020
TL;DR: A CNN based method for plant disease detection has been proposed here and performs well in terms of time complexity and the area of the infected region.
Abstract: Agricultural productivity is a key component of Indian economy. Therefore the contribution of food crops and cash crops is highly important for both the environment and human beings. Every year crops succumb to several diseases. Due to inadequate diagnosis of such diseases and not knowing symptoms of the disease and its treatment many plants die. This study provides insights into an overview of the plant disease detection using different algorithms. A CNN based method for plant disease detection has been proposed here. Simulation study and analysis is done on sample images in terms of time complexity and the area of the infected region. It is done by image processing technique. A total of 15 cases have been fed to the model, out of which 12 cases are of diseased plant leaves namely, Bell Paper Bacterial Spot, Potato Early Blight, Potato Late Blight, Tomato Target Spot, Tomato Mosaic Virus, Tomato Yellow Leaf Curl Virus, Tomato Bacterial Spot, Tomato Early Blight, Tomato Late Blight, Tomato Leaf Mold, Tomato Septoria Leaf Spot and Tomato Spider Mites and 3 cases of healthy leaves namely, Bell Paper Healthy, Potato Healthy and Tomato Healthy. Test accuracy is obtained as 88.80%. Different performance matrices are derived for the same.

66 citations


Journal ArticleDOI
TL;DR: The current understanding of the molecular interactions that occur between C. beticola and its sugar beet host is summarized and the known virulence arsenal of this pathogen is highlighted as well as its ability to overcome currently used disease management strategies.
Abstract: Cercospora leaf spot, caused by the fungal pathogen Cercospora beticola, is the most destructive foliar disease of sugar beet worldwide. This review discusses C. beticola genetics, genomics, and biology and summarizes our current understanding of the molecular interactions that occur between C. beticola and its sugar beet host. We highlight the known virulence arsenal of C. beticola as well as its ability to overcome currently used disease management strategies. Finally, we discuss future prospects for the study and management of C. beticola infections in the context of newly employed molecular tools to uncover additional information regarding the biology of this pathogen. TAXONOMY Cercospora beticola Sacc.; Kingdom Fungi, Phylum Ascomycota, Class Dothideomycetes, Order Capnodiales, Family Mycosphaerellaceae, Genus Cercospora. HOST RANGE Well-known pathogen of sugar beet (Beta vulgaris subsp. vulgaris) and most species of the Beta genus. Reported as pathogenic on other members of the Chenopodiaceae (e.g., lamb's quarters, spinach) as well as members of the Acanthaceae (e.g., bear's breeches), Apiaceae (e.g., Apium), Asteraceae (e.g., chrysanthemum, lettuce, safflower), Brassicaceae (e.g., wild mustard), Malvaceae (e.g., Malva), Plumbaginaceae (e.g., Limonium), and Polygonaceae (e.g., broad-leaved dock) families. DISEASE SYMPTOMS Leaves infected with C. beticola exhibit circular lesions that are coloured tan to grey in the centre and are often delimited by tan-brown to reddish-purple rings. As disease progresses, spots can coalesce to form larger necrotic areas, causing severely infected leaves to wither and die. At the centre of these spots are black spore-bearing structures (pseudostromata). Older leaves often show symptoms first and younger leaves become infected as the disease progresses. MANAGEMENT Application of a mixture of fungicides with different modes of action is currently performed although elevated resistance has been documented in most employed fungicide classes. Breeding for high-yielding cultivars with improved host resistance is an ongoing effort and prudent cultural practices, such as crop rotation, weed host management, and cultivation to reduce infested residue levels, are widely used to manage disease. USEFUL WEBSITE: https://www.ncbi.nlm.nih.gov/genome/11237?genome_assembly_id=352037.

35 citations


Journal ArticleDOI
TL;DR: It is hypothesize that the most common endophytic fungi are latent pathogens in the host and may cause plant disease when the host becomes weakened by senescence or changed cultivation condition.
Abstract: Chinese mesona (Platostoma palustre) plays an important role as special crop in Southeast Asia and Taiwan for the production of herbal tea, grass jelly, and further processed food. In order to assess the potential threat of fungi to Chinese mesona, we surveyed isolates from symptomless plants in the area of mesona production, as well as from leaf spots of potted plants in a garden shop and a plantation in a botanical garden in Taiwan. From leaves, stems, and roots of 15 symptomless plants sampled at five collection events over two years, 154 isolates from 810 surface-sterilized plant fragments were obtained and identified based on DNA sequence data of the internal transcribed spacer region, and partially of the β-tubulin and histone H3 genes. The most common species belonged to the genera Cercospora, Colletotrichum, and Fusarium and were considered to be potential plant pathogens. Latent pathogenicity was confirmed by an infection experiment with an endophytic strain of Corynespora cassiicola. Observation of leaf spot disease associated with Cercospora kikuchii suggested pathogenicity of this fungus, which was also isolated as an endophyte from symptomless leaves. We hypothesize that the most common endophytic fungi are latent pathogens in the host and may cause plant disease when the host becomes weakened by senescence or changed cultivation condition. Leaf spots of plants in the botanical garden were associated with a species of Pseudocercospora, which was not found among the endophytic isolates and is newly described based on morphology and analysis of translation elongation factor 1 alpha gene sequences.

25 citations


Journal ArticleDOI
TL;DR: A large regional and yearly variation in disease severity, distribution and impact on yield is verified, emphasizing the need to adapt fungicide applications to the actual need based on locally adapted risk assessment systems.
Abstract: Fungal plant diseases driven by weather factors are common in European wheat and barley crops. Among these, septoria tritici blotch (Zymoseptoria tritici), tan spot (Pyrenophora tritici-repentis), and stagonospora nodorum blotch (Parastagonospora nodorum) are common in the Nordic-Baltic region at variable incidence and severity both in spring and winter wheat fields. In spring barley, net blotch (Pyrenophora teres), scald (Rhynchosporium graminicola, syn. Rhynchosporium commune) and ramularia leaf spot (Ramularia collo-cygni) are common yield limiting foliar diseases. We analysed data from 449 field trials from 2007 to 2017 in wheat and barley crops in the Nordic-Baltic region and explored the differences in severity of leaf blotch diseases between countries and years, and the impact of the diseases on yield. In the experiments, septoria tritici blotch dominated in winter wheat in Denmark and southern Sweden; while in Lithuania, both septoria tritici blotch and tan spot were common. In spring wheat, stagonospora nodorum blotch dominated in Norway and tan spot in Finland. Net blotch and ramularia leaf blotch were the most severe barley diseases over large areas, while scald occurred more locally and had less yield impact in all countries. Leaf blotch diseases, with severity >50% at DC 73–77, caused an average yield loss of 1072 kg/ha in winter wheat and 1114 kg/ha in spring barley across all countries over 5 years. These data verify a large regional and yearly variation in disease severity, distribution and impact on yield, emphasizing the need to adapt fungicide applications to the actual need based on locally adapted risk assessment systems.

24 citations


Journal ArticleDOI
TL;DR: Using image texture analysis of olive plant leaves, correlation in between the signatures of Neofabrea leaf spot disease and Peacock leaf spot diseases with some texture features is identified.

23 citations


Journal ArticleDOI
TL;DR: Treatment with bioformulation treatment T3, notably increased plant height, number of leaves per plant, chlorophyll, carotenoids, and total soluble sugar content followed by formulations number T4, T2, and T1, however, total soluble protein content was observed to be less in T3 as compared to control.
Abstract: Leaf spot disease caused by Curvularia lunata is one of the major constraints affecting the cultivation of maize in India. Recently, it has been reported that the severity of curvularia leaf spot was prevalent in moderate to severe intensities and cause extensive damage to the crop thus lowering the yields. In the present study, in vivo preventive effect of Lawsonia inermis Linn. bioformulation on curvularia leaf spot disease of maize has been studied. All the experiments were conducted in pots. Percent disease index (PDI), percent efficacy of disease control (PEDC), chlorophyll contents, total carotenoids, and others various growth characteristics like plant height, number of leaves per plant, total carbohydrate and protein content were recorded. Percent seed germination was also observed for seeds treated with all formulations. A significant control of leaf spot disease was recorded with bioformulations treatment T3 [seeds were treated with partially purified acetone extract (4 ml): 100% clove bud oil cake (4 ml): 100% cow dung (2 ml)], T4 [seeds were treated with partially purified acetone extract (3 ml): 100% clove bud oil cake (4 ml): 100% cow dung (3 ml)], T2 [seeds were treated with 100% alcoholic crude extract (2 ml): 100% clove bud oil cake (6 ml): 100% cow dung (2 ml)] and T1 [seeds were treated with 100% alcoholic crude extract (4 ml): 100% clove bud oil cake (4 ml): 100% cow dung (2 ml)] as compared to other bioformulation treatments and its PDI and PEDC were recorded 9.10%, 10.00%, 17.50%, 19.00% and 89.47%, 88.43%, 79.76%, 78.03%, respectively. Results showed that treatment with bioformulation treatment T3, notably increased plant height, number of leaves per plant, chlorophyll, carotenoids, and total soluble sugar content followed by formulations number T4, T2, and T1. However, total soluble protein content was observed to be less in T3 as compared to control. This study suggests that these bioformulations could be essential towards sustainable agricultural science deprived of harming the ecosystem. The synthesized bioformulations have enormous potential to be commercially explored for agriculture use.

22 citations


Journal ArticleDOI
TL;DR: This study provides useful information for disease diagnosis and management for Bipolaris leaf spot in maize and finds that B. zeicola isolates were mainly distributed in high altitude and cool mountainous areas, while B. maydis was more widely distributed in Sichuan Province.
Abstract: Many species of the genus Bipolaris are important plant pathogens and often cause leaf spot, root rot, and seedling blight in an extremely wide range of hosts around the world. In recent years, maize leaf spot caused by Bipolaris species has frequently occurred with complex symptoms and is becoming increasingly serious in Sichuan Province of China. To investigate the population diversity of Bipolaris spp. and their corresponding symptoms in maize, 747 samples of maize leaf spot were collected from 132 sampling sites in 19 administrative districts of Sichuan Province from 2011 to 2018. Based on morphological characteristics, pathogenicity testing, and phylogenetic analysis of the rDNA internal transcribed spacer (ITS) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) genes, a total of 1186 Bipolaris isolates were identified as B. maydis, B. zeicola, B. cynodontis, B. oryzae, B. setariae, and B. saccharicola, among which B. maydis and B. zeicola were the dominant pathogenic species, accounting for 57.34% and 42.07% of the isolates, respectively. We found that B. zeicola isolates were mainly distributed in high altitude and cool mountainous areas, while B. maydis was more widely distributed in Sichuan Province. The typical symptoms caused by the Bipolaris species were clearly distinct in maize. The typical symptoms caused by B. maydis were elongated strip lesions, or fusiform, elliptical lesions, and those caused by B. zeicola were narrow linear lesions. Herein, B. saccharicola was first reported on maize and caused subrotund lesions. This study provides useful information for disease diagnosis and management for Bipolaris leaf spot in maize.

21 citations


Journal ArticleDOI
TL;DR: This study revealed the first emaravirus infecting pear trees and its association with a severe pear chlorotic leaf disease and revealed the profile distribution of viral RNA reads from the RNA-seq libraries of three samples along the RNA1 to RNA5 of an emarvirus.
Abstract: Pear chlorotic leaf spot (PCLS) is a recently emerged disease of commercially cultivated sandy pear (Pyrus pyrifolia) trees in central and southern China. By integrating high-throughput sequencing ...

18 citations


Journal ArticleDOI
TL;DR: High disease severity, population expansion, intraspecies diversity, and increased range of experimental hosts were seen in the emergence of Alternaria disease on ornamentals.
Abstract: Serious outbreaks of Alternaria leaf spot and plant decay have recently been recorded on several ornamental plants in the Biella Province (Northern Italy). Twenty-two fungal isolates were obtained from Alternaria infected plant tissues from 13 ornamental hosts. All the isolates were identified morphologically as small-spored Alternaria species. Multilocus sequence typing, carried out by means of ITS, rpb2, tef1, endoPG, Alt a 1, and OPA10-2, assigned 19 isolates as Alternaria alternata, two isolates as belonging to the Alternaria arborescens species complex, and one isolate as an unknown Alternaria sp. Haplotype analyses of ornamental and reference A. alternata isolates from 12 countries identified 14 OPA10-2 and 11 endoPG haplotypes showing a relatively high haplotype diversity. A lack of host specialization or geographic distribution was observed. The host range of the studied A. alternata isolates expanded in cross-pathogenicity assays, and more aggressiveness was frequently observed on the experimental plants than on the host plants from which the fungal isolates were originally isolated. High disease severity, population expansion, intraspecies diversity, and increased range of experimental hosts were seen in the emergence of Alternaria disease on ornamentals. More epidemiological and molecular studies should be performed to better understand these diseases, taking into consideration factors such as seed transmission and ongoing climate changes.

17 citations


Journal ArticleDOI
TL;DR: Investigation of micro-fungi species associated with leaf spot of Allanblackia floribunda in Southern Nigeria found that P. palmarum was the most prevalent out of all micro-Fungi Species associated with A. florIBunda in all locations.
Abstract: Fruit of Allanblackia floribunda is an active ingredient in the pharmaceutical industry. Fruit production in the species is hindered by incidence of pathogenic fungi leading to economic loss. This study was conducted to investigate micro-fungi species associated with leaf spot of A. floribunda. Field surveys were carried out in natural stands containing matured A. floribunda trees located at Owu Ikija, Ogun State (6.80°N, 4.03°E) and Benin, Edo State (6.29°N and 5.58°E) in Southern Nigeria. Diseased leaf samples were collected during wet and dry seasons. Pure cultures of fungal isolates obtained from the leaf samples were examined to determine their cultural and morphological characteristics. Percentage incidence of micro-fungi in each location was estimated. Leaves of healthy seedlings were sprayed with 104 conidial/ml spore concentration of fungal isolates to determine their pathogenicity. Fourteen fungal species were isolated from leaves of A. floribunda across the two sites. Aspergillus spp., Macrophomina phaseolina, Penicillium species, Pestalotia palmarum, Rhizopus nigricans and Trichoderma pseudokoningii were isolated from both sites during both seasons. Fusarium oxysporum, Lasiodiplodia theobromae, Penicillium javanicum and Pythium aphanidermatum were present at Owu Ikija while Colletotrichum capsici, C. coccodes and Curvularia lunata were present at Benin with fungal incidence of 12.5, 12.5 and 4.17%, respectively. P. palmarum had modal fungal incidence (35.29%) at Benin followed by T. pseudokoningii at Owu-Ikija with frequency value of 18.75 and 17.54%, respectively. P. palmarum was the most prevalent out of all micro-fungi species associated with A. floribunda in all locations. Pathogenicity test was negative for all tested isolates, variety of micro-fungi are associated with A. floribunda. Key words: Allanblackia floribunda, fruit, fungal isolates, leaf samples, pathogenicity.

Journal ArticleDOI
TL;DR: A survey of fungal leaf spots on macadamia trees in 20 commercial orchards in Queensland revealed two distinctive types of symptoms that were identical to the respective field disease symptoms.
Abstract: Extensive leaf spot was observed on all leaves of young macadamia trees planted in new orchards in Queensland, Australia. The loss in photosynthetic ability of these trees may contribute to their demise and poor establishment compared to trees without symptoms. A survey of fungal leaf spots on macadamia trees in 20 commercial orchards in Queensland revealed two distinctive types of symptoms. Leaves showing circular dark brown spots with yellow halos (Type 1) and irregular dark brown spots (Type 2) were collected. Fungal isolates associated with the infected leaves were identified by morphological characteristics and DNA sequencing as Neopestalotiopsis clavispora for Type 1 spots and Colletotrichum siamense for Type 2 spots. Koch’s postulates were fulfilled for N. clavispora and C. siamense. Pathogenicity assays showed that both fungi caused severe leaf spots, which are identical to the respective field disease symptoms. In order to clearly characterise them, the two leaf spots were named as Pestalotiopsis leaf spot (Type 1 spots) and Colletotrichum leaf spot (Type 2 spots). This is the first report of N. clavispora and C. siamense causing leaf spots in macadamia in Australia.


Journal ArticleDOI
TL;DR: Berberine is a promising bioactive compound which may be developed as a lead compound in a new fungicide to control brown leaf spot and blast diseases of rice.
Abstract: Berberine showed in vitro remarkable antifungal activity against rice pathogens including Bipolaris oryzae, Curvularia lunata, Pyricularia oryzae and Rhizoctonia solani with MIC values of 125 μg/mL. It showed potent preventative and curative activities in suppression of brown leaf spot disease of a susceptible Oryza sativa var. KDML 105 under greenhouse conditions. Berberine at 5 mg/mL showed effective brown leaf spot disease suppression in rice when applied before pathogen inoculation. It also showed higher fungicidal activity in suppression of brown leaf spot disease in plants aged 30 and 60 days than did difenoconazole and mancozeb when applied after pathogen inoculation. Moreover, berberine at 10 mg/mL significantly (P < 0.05) reduced the percentage of rice blast disease severity by 49.81%, which was similar to the action of difenoconazole and mancozeb when applied twice under field conditions. However, it showed low fungicidal activity against dirty particle disease, a complex disease of rice, under field conditions when compared with synthetic fungicides. These results indicated that berberine is a promising bioactive compound which may be developed as a lead compound in a new fungicide to control brown leaf spot and blast diseases of rice.


Proceedings ArticleDOI
16 Nov 2020
TL;DR: In this paper, the integration of computer vision and computational intelligence for tomato Septoria leaf spot necrotic and chlorotic region computational assessment is proposed, where a new tomato leaf disease index (tomLDI) optimized using artificial bee colony (ABC) was developed by normalizing visible red reflectance, and introducing red-green and red-blue reflectance ratios to enhance tomato leaf spots pixels and reducing sensitivity to healthy green pixels.
Abstract: Visual inspection of plant health status and disease severity may yield subjective assessments due to error-prone sphere of colors and textures as affected by angular photosynthetic light source and the complexity of chlorosis. Quantification of damages on leaves due to destructive diseases is paramount for plant and pathogen interactions. To address this challenge, the proposed solution is the integration of computer vision and computational intelligence for tomato Septoria leaf spot necrotic and chlorotic region computational assessment. Dataset contains healthy and diseased tomato leaves that were captured individually. Non-vegetation pixels removal was done using CIELab color space. RGB color components and five Haralick texture features were extracted from the segmented leaf. Hybrid neighborhood component analysis and ReliefF algorithm were employed to select the important predictors resulting to RGB-entropy vector. A new tomato leaf disease index (tomLDI) optimized using artificial bee colony (ABC) was developed by normalizing visible red reflectance, and introducing red-green and red-blue reflectance ratios to enhance Septoria leaf spots pixels and reducing sensitivity to healthy green pixels. KNN bested classification tree, linear discriminant analysis and Naive Bayes in detecting Septoria leaf disease with accuracy of 97.46%. Deep transfer image regression was tested using raw infected leaf images and the tomLDI transformed colored channels through MobileNetV2, ResNet101 and InceptionV3. Using tomLDI channel, MobileNetV2 and ResNet101 bested other networks in estimating leaf diseased region percentage and number of Septoria spots with R2 values of 0.9930 and 0.9484 respectively. tomLDI channel proved to be more accurate than using raw images for regression.

Journal ArticleDOI
TL;DR: SSG is a promising broad-spectrum biocontrol agent for a variety of plant diseases caused by diverse pathogens and provides the greatest control to two diseases with hydrangea anthracnose and rhododendron Ramorum blight.

Journal ArticleDOI
Feng-Min Zhang1, Wei He1, Chun-Ya Wu1, Kai Sun1, Wei Zhang1, Chuan-Chao Dai1 
TL;DR: In outdoor pot and greenhouse conditions, P. liquidambaris significantly reduced leaf spot and root rot diseases while increasing peanut yields and the demonstrated ability of P.Liquidambaris to control disease makes it a strong biocontrol agent candidate.
Abstract: Soil-borne pathogens severely reduce the agricultural yield of peanuts. Accordingly, the application of biocontrol agents for plant disease management is a potentially powerful method for peanut cultivation. This study aimed to (1) evaluate the protective effect of the fungal endophyte Phomopsis liquidambaris for peanut plants against leaf spot disease caused by Colletotrichum gloeosporioides and against root rot disease caused by Fusarium oxysporum under outdoor conditions and (2) explore the potential biological control mechanisms of P. liquidambaris under greenhouse conditions. In our outdoor pot experiments, P. liquidambaris significantly reduced leaf spot and root rot diseases while increasing peanut yields. Under greenhouse conditions, P. liquidambaris–induced resistance against pathogens was associated with increased antioxidant enzyme activity, callose deposition, cell lignification, and phytoalexins accumulation. The demonstrated ability of P. liquidambaris to control disease makes it a strong biocontrol agent candidate.

Journal ArticleDOI
TL;DR: Results indicated that young and intact leaves of horseradish and cabbage were less susceptible to infection and also suggested the potential for cross-infection between these two hosts and the possible association of some haplotypes with the geographic area.
Abstract: Leaf spot diseases caused by Alternaria species have been reported worldwide in plants in the Brassicaceae family. However, there is little information on Alternaria species causing diseases in hor...

Journal ArticleDOI
TL;DR: This is the first report of species of Neopestalotiopsis causing mango grey leaf spot disease in Mexico.
Abstract: Mango is one of the most popular and nutritious fruits in the world and Mexico is the world’s largest exporter. There are many diseases that directly affect fruit yield and quality. During the period 2016–2017, leaves with grey leaf spots were collected from 28 commercial mango orchards distributed in two main production areas in Sinaloa State of Mexico, and 50 Neopestalotiopsis isolates were obtained. Fungal identification of 20 representative isolates was performed using morphological characterization and phylogenetic analysis based on the internal transcribed spacer (ITS) region of ribosomal DNA, part of the translation elongation factor 1-alpha (TEF) and the β-tubulin (TUB) genes. Phylogenetic analysis indicated that the 20 isolates from this study formed four consistent groups, however, overall tree topologies do not consistently provide a stable and sufficient resolution. Therefore, even though morphological and phylogenetic separation is evident, these isolates were not assigned to any new taxa and were tentatively placed into four clades (clades A–D). Pathogenicity tests on detached mango leaves of cv. Kent showed that the 20 isolates that belong to the four Neopestalotiopsis clades from this study and induce lesions on mango leaves. This is the first report of species of Neopestalotiopsis causing mango grey leaf spot disease in Mexico.

Journal ArticleDOI
TL;DR: This report is the first of a disease on P. odoratum caused by C. spaethianum, and the fungus isolated from the diseased leaves was identified based on pathogenicity, morphology and molecular characterization.
Abstract: In August 2014, leaf spots were found on Polygonatum odoratum in Jilin Province in China. The fungus isolated from the diseased leaves was identified as Colletotrichum spaethianum based on pathogenicity, morphology and molecular characterization. The fungus was re-isolated from lesions that developed on leaves after inoculation. This report is the first of a disease on P. odoratum caused by C. spaethianum.

Journal ArticleDOI
TL;DR: Morphology and phylogenetic reconstruction indicated that the causal agent of the described symptoms was Neopestalotiopsis rosae, marking the first report anywhere in the world of this species infecting strawberry.
Abstract: In the 2017 strawberry season, several transplant losses reaching 50% were observed in Zamora, Michoacan Valley, Mexico, due to a new fungal disease associated with root rot, crown rot, and leaf spot. In this year the disease appeared consistently and increased in the following seasons, becoming a concern among strawberry growers. Thus, the aim of this research was to determine the etiology of the disease and to determine the in vitro effect of fungicides on mycelial growth of the pathogen. Fungal isolates were obtained from symptomatic strawberry plants of the cultivars 'Albion' and 'Festival' and were processed to obtain monoconidial isolates. Detailed morphological analysis was conducted. Concatenated phylogenetic reconstruction was conducted by amplifying and sequencing the translation elongation factor 1 α, β-tubulin partial gene, and the internal transcribed spacer region of rDNA. Pathogenicity tests involving inoculation of leaves and crowns reproduced the same symptoms as those observed in the field, fulfilling Koch's postulates. Morphology and phylogenetic reconstruction indicated that the causal agent of the described symptoms was Neopestalotiopsis rosae, marking the first report anywhere in the world of this species infecting strawberry. N. rosae was sensitive to cyprodinil + fludioxonil, captan, iprodione, difenoconazole, and prochloraz.


Journal ArticleDOI
TL;DR: This is the first report of QoI fungicide-resistant C. sojina isolates in Michigan, Minnesota, and Nebraska and expands the geographical distribution of quinone outside inhibitor (QoI) fungicides to 18 states in total.
Abstract: Frogeye leaf spot, caused by Cercospora sojina, is an important disease of soybean (Glycine max) in the United States. An important tactic to manage frogeye leaf spot is to apply foliar fungicides....


Journal ArticleDOI
27 Oct 2020-Agronomy
TL;DR: An increase in the concentration of the stimulant applied as a spray resulted in a significant increase in its effectiveness; plants in plots with the highest dose of amino acid solution (Variant III) had the highest aesthetic and functional values.
Abstract: The purpose of this research was to assess the functional value of the “Super Trawnik” lawn mixture. The studies were carried out between 2017 and 2019 at the Experimental Station of the University of Agriculture in Krakow (50°07′ N, 20°05′ E), and the experimental factor was the AGRO-SORB® Folium, a biostimulant containing amino acids and applied at three doses: 1, 2, and 3 L·ha−1. Lawn visual quality was assessed on a 9-point scale, with 10–11 mowings at 4 cm during the growing period. An increase in the concentration of the stimulant applied as a spray resulted in a significant increase in its effectiveness; plants in plots with the highest dose of amino acid solution (Variant III) had the highest aesthetic and functional values. The AGRO-SORB® Folium reduced the occurrence of fungal diseases; compared to control plants, there was a 16% reduction of Fusarium patch (Microdochium nivale) infection and a 20% reduction of Dreschlera leaf spot (Drechslera siccans). Satisfactory effects were also recorded on plots where the product was applied at a dose of 2 L·ha−1 (Variant II). Those plots had more favourably rated turf, with higher resistance of plants to Fusarium patch by 12% and to Dreschlera leaf spot by 20% compared to control.

Journal ArticleDOI
Yaowen Zhang1, Rong Shen1, Yixue Mo1, Qiqin Li1, Wei Lin1, Gaoqing Yuan1 
TL;DR: Based on morphological observations and polygenic analyses, the pathogen causing leaf spots on S. nobilis was identified as Colletotrichum siamense and was confirmed as Koch's postulates.
Abstract: Sterculia nobilis is an important tropical woody plant with high ornamental and economic value. At present, there are few reports of diseases on this plant. In August 2018, an unknown leaf spot disease was observed on S. nobilis in Nanning, China, affecting the inner leaves of the canopy and causing considerable defoliation. The pathogen was isolated, and pathogenicity tests carried out on detached leaves to verify Koch's postulates. Based on morphological observations and polygenic analyses, the pathogen causing leaf spots on S. nobilis was identified as Colletotrichum siamense.

Journal ArticleDOI
TL;DR: The proper timing of fungicide application and rotation with different modes of action provided a feasible disease management option for pomegranate growers in the Southeast United States.
Abstract: Pomegranate (Punica granatum L.) has emerged as an alternative fruit crop for growers dealing with devastating threats to citrus and avocado in the southeastern United States. However, foliar and fruit diseases are major constraints to commercial pomegranate production. Replicated field trials were performed in 2015 at three separate sites in Florida (Dover, Plant City, and Parrish) to evaluate Merivon (pyraclostrobin and fluxapyroxad), Luna Experience (fluopyram + tebuconazole), and a rotational program consisting of these two fungicides as well as Penncozeb 75DF (mancozeb) for the management of leaf spot and fruit rot of pomegranate. The fungicide programs were evaluated on the varieties Vietnam in Dover, FL; Angel Red in Plant City, FL; as well as Christina, Azadi, Vikusnyi, Alsirinnar, Sakerdze, and Wonderful in Parrish, FL. Mean leaf spot severity varied across sites at the end of each trial in August, with values ranging from 4.5 to 62.5% in Plant City, 7.5 to 45.8% in Dover, and 4.5 to 54.2% in Parrish. Based on area under the disease progress curve, all treatments that included at least one at bloom application significantly reduced disease levels compared with postbloom treatments and the nontreated control across all trial sites. Based on fruit rot incidence, Luna Experience and Merivon, when applied twice at bloom in the beginning of the season, reduced disease by 66.6 and 88.4%, respectively, in comparison with the nontreated control in Plant City. A rotational program further reduced disease by at least 97% at the end of the season in Parrish. The proper timing of fungicide application and rotation with different modes of action provided a feasible disease management option for pomegranate growers in the Southeast United States.

Journal ArticleDOI
TL;DR: Preparation of different bioformulations of Lawsonia inermis Linn (Henna) leaves and its in vitro antifungal activity were evaluated against Curvularia lunata (Wakker) Boedijn caused leaf spot disease in maize and optimum activity was observed in formulation number 4.
Abstract: In the present study preparation of different bioformulations of Lawsonia inermis Linn. (Henna) leaves and its in vitro antifungal activity were evaluated against Curvularia lunata (Wakker) Boedijn...

Journal ArticleDOI
TL;DR: This is the first report of different phylogenetic species of Neopestalotiopsis causing dieback, leaf and stem lesions in eucalyptus cuttings and provides a basis for developing novel disease management strategies in forest nurseries.
Abstract: Brazil is the leader in the global ranking of forest productivity; however, one of the major challenges to eucalyptus production is the existence of fungal diseases. A severe epidemic caused by pestalotiopsis‐like fungi was observed in a forest nursery in Brazil, causing a huge impact on the eucalyptus micropropagation stages. The aims of the present study were to identify the causal agents associated with pestalotiopsis leaf spot and dieback in eucalyptus, assess their pathogenicity to different commercial clones, and evaluate which conditions favour conidial germination and infection by the pathogens. Multilocus phylogenetic analyses using ITS, TEF and TUB identified the isolates as members of Neopestalotiopsis and segregated them into three species. Isolates from all Neopestalotiopsis spp. caused symptoms on unwounded eucalyptus leaves and disease development was strongly dependent on long leaf wetness periods (≥72 h). All four commercial clones tested were susceptible to the pathogen. These results clearly dispute the commonly held assumption that pestalotioid fungi are weak and opportunistic pathogens. This is the first report of different phylogenetic species of Neopestalotiopsis causing dieback, leaf and stem lesions in eucalyptus cuttings and provides a basis for developing novel disease management strategies in forest nurseries.