Leaf Spot Research Articles

Cercospora leaf spot management with nitrogenous fertilizers in cotton is dependent on the disease amount in the plant canopies

The aim of this study was to examine the impact of both organic and inorganic nitrogen fertilizers on the intensity and epidemiological components of Cercospora leaf spot across three different canopies of cotton plants, specifically the variety DP ACALA 90, under field conditions. Fertilizers used in the study included bovine manure, Jatropha curcas seedcake, poultry manure, and urea (the latter serving as a control). These were applied at 20 days after plant emergence and then during the flowering stage until the total nitrogen (N) dose reached 50, 100, 150, or 200 kg N per hectare. The incidence and severity of the disease were assessed starting at the reproductive stage B1 (the first visible flower bud) across the lower, middle, and upper canopies of four cotton plants, with six evaluations conducted over time. To calculate the initial inoculum (Y0) and the disease progress rate (r), the Exponential, Gompertz, and Logistic models were employed based on temporal data. The study was designed as a randomized complete block with a 4x4 factorial arrangement (fertilizer type x dose), and mean comparisons were made using Tukey's test (p ≤ 0.05). It was found that disease intensity within each canopy level varied in response to the type of nitrogen source and the applied dose, with the severity of the disease (including the area under the disease progress curve) being particularly influenced. A significant interaction between the type of fertilizer and the dose regarding the intensity of Cercospora leaf spot was observed. The Exponential model most accurately depicted the disease's temporal progression. Notably, poultry manure and urea were the fertilizers that most adversely influenced the intensity and initial inoculum (Y0) of Cercospora leaf spot across the various canopies of the cotton plants. The findings suggest that the use of organic fertilizers in cotton cultivation could represent a viable sustainable management strategy.

Screening of mungbean germplasm for resistance against Cercospora leaf spot under natural field conditions

Mung bean is an excellent protein source pulse crop grown throughout the world. Punjab province accounts for 80% area and production of mung bean in Pakistan. Mung bean is cultivated on a large scale for its green manuring ability and grain consumption. Mungbean is prone to economically important fungal, bacterial, and viral diseases. Cercospora leaf spot (CLS) caused by Cercospora canescens is one of the most serious disease concerns in Pakistan. The pulses program at the National Agriculture Research Centre, Islamabad is trying hard to get the resistant germplasm against CLS. Sixty-eight advance lines/approved varieties were evaluated in the augmented design under natural field conditions. Forty-one advance lines/approved varieties were found resistant and twenty-five advance lines/approved varieties were found moderately resistant. Two advanced lines/approved varieties did not perform well and were susceptible to CLS infection. This data indicates that the germplasm at pulses program is excellent in resistance against CLS under natural field conditions in the Arid Zone and can serve as potential future varieties.

Assessing the Effectiveness of Neem oil and Microalgae in the Management of Cowpea (Vigna unguiculata L.) Leaf Spot Caused by Alternaria spp.

The current study aimed to assess the effectiveness of neem oil and microalgae in controlling leaf spot caused by Alternaria spp. in cowpea (Vigna unguiculataL.). The research was conducted during the Zaid season of 2022 at the Central Research Field of the Department of Plant Pathology, SHUATS, Prayagraj, Uttar Pradesh, using a Randomized Block Design with three replications and seven treatments. Analysis of variance (ANOVA) was utilized to draw conclusions from the data. Leaf spot disease caused by Alternaria spp poses a significant threat to cowpea crops, resulting in yield losses and decreased plant vigor. An in vivo study was carried out to evaluate the impact of different concentrations of microalgae combined with neem oil at 1% on plant growth parameters and Disease Intensity (%). The application of microalgae @540 grams in various splits and neem oil @1% was done. Among all the treatments, T4 (Microalgae 48gms @5 DAS 96gms@15,45 DAS + Neem oil @1% showed promising results. Notably, the T4 treatment significantly increased plant height (84.63 cm) and the number of branches(10.83) at60DAS. Moreover, an increased numberof nodules per plant (21.44) was observed at 75 DAS, indicating improved root health and nitrogen fixation. Additionally, the treatment led to longer pod length (34.44 cm) in three pickings, suggesting enhanced yield potential. Furthermore, the combined application of microalgae and neem oil resulted in a significant reduction in disease intensity, with a notable decrease of 24.47% compared to untreated plants and those treated with chemicals (Bavistin). This indicates that the use of microalgae and neem oil together effectively suppressed leaf spot disease caused by Alternaria spp. in cowpea, thereby improving plant health and productivity. In conclusion, these findings underscore the potential use of eco-friendly alternatives like microalgae and neem oil for managing leaf spot disease in cowpea cultivation. Further research in this area is recommended for sustainable agricultural practices.

Searching for pathogenic fungi of Passiflora foetida sensu lato in Colombia, South America, with potential for classical biological control in Australia

ABSTRACT Interest in plant pathogens for classical biological control (CBC) of invasive introduced plants has increased steadily since the 1970s. The introduced plant Passiflora foetida sensu lato invades large tracts of land across northern Australia and CBC represents a possible solution to reduce its abundance and spread. Field surveys for foliar fungal pathogens of P. foetida s.l. were performed between 2017 and 2020 in Colombia. Molecular sequencing was used to confirm the identity of plants surveyed at each site and to explore genetic variation between sites. Leaf spots of various sizes and sometime associated with chlorosis as well as necrosis of leaf edges were the main disease symptoms observed. These symptoms were not severe and did not appear to affect plant growth. No disease symptoms caused by obligate biotrophic fungi nor girdling lesions on stems were observed. Of the 125 fungal isolates recovered from the collected diseased material, only 21 were considered as pathogenic on P. foetida s.l. in detached-leaf assays. Morphological examinations and sequencing of the 21 pathogenic isolates revealed that they belong to 11 genera. Based on the low severity of disease symptoms observed in the field, we conclude that these isolates do not warrant further investigations as potential CBC agents.

Evaluation and Control of Fusarium acuminatum Causing Leaf Spot in Saposhnikovia divaricata in Northeast China.

Saposhnikovia divaricata is an authentic Chinese herbal medicine in Northeast China named Guanfangfeng, which is made from very high-quality plants for sufficient efficacy. However, leaf spot causes a very large reduction in the yield and quality of S. divaricata in Shuangyashan (46.58°N, 131.28°E), Northeast China. A total of 18 isolates were isolated from the diseased leaves of S. divaricata, following Koch's postulates, and identified as Fusarium acuminatum based on morphological, molecular biological, and phylogenetic tree analyses. To the authors' knowledge, this is the first report of F. acuminatum causing S. divaricata leaf spot in China. F. acuminatum infected perilla and mung beans but not foxtail millet, peanuts, wheat, peas, rye, red beans, or sorghum. Susceptibility assessment of F. acuminatum to fungicides using the mycelial growth rate method showed that isolates of F. acuminatum were most sensitive to prochloraz, with effective concentration values of 0.0005413 to 0.0009523 μg/ml. In the two field experiments, the average control efficacy of prochloraz at 0.450 g/liter on S. divaricata leaf spot caused by F. acuminatum was 75.42%. Therefore, nonhost plant rotation or intercropping with suitable chemical fungicides may be used to control S. divaricata leaf spot. This study's results provide a theoretical basis for controlling S. divaricata leaf spot and will facilitate the development of effective disease management programs.

PEPPER AND CORN LEAVES CLASSIFICATION AND SEVERITY IDENTIFICATION USING HYBRID OPTIMIZATION BASED U-NET MODEL

Abstract An agricultural product plays a major role in the economical growth of developing countries. Agricultural products like pepper and corn are the essential crops with respect to human health food security. But, these two crops are prone to different diseases such as gray leaf spot, common rust and fruit rot which affects the productivity of crops. Further, the severity identification is also a challenging one. To address these limitations, this work presents different approaches for identifying the crop lesions and predicting the severity and thereby increasing the productivity of crops. The development of the proposed model includes steps such as dataset collection, noise removal, segmentation, feature extraction, classification and severity prediction. Initially, the crop images are pre-processed by the median filter and the pre-processed images are processed are segmented, extracted and classified by the optimized U-Net model. Moreover, hybrid optimizer which is the integration of GJA (Golden jackal algorithm) and RDA (Red deer algorithm) are utilized for precise segmentation and classification. Finally, the severity prediction is computed for the diseased leaves by the measuring the size of image pixels. The experimentation is carried out on the PlantVillage dataset; the accuracy and precision values achieved are 99.2% and 99.1%. Thus, the experimental outcomes show the effectiveness and stability of the model.

An efficient deep learning model for tomato disease detection

Tomatoes possess significant nutritional and economic value. However, frequent diseases can detrimentally impact their quality and yield. Images of tomato diseases captured amidst intricate backgrounds are susceptible to environmental disturbances, presenting challenges in achieving precise detection and identification outcomes. This study focuses on tomato disease images within intricate settings, particularly emphasizing four prevalent diseases (late blight, gray leaf spot, brown rot, and leaf mold), alongside healthy tomatoes. It addresses challenges such as excessive interference, imprecise lesion localization for small targets, and heightened false-positive and false-negative rates in real-world tomato cultivation settings. To address these challenges, we introduce a novel method for tomato disease detection named TomatoDet. Initially, we devise a feature extraction module integrating Swin-DDETR’s self-attention mechanism to craft a backbone feature extraction network, enhancing the model’s capacity to capture details regarding small target diseases through self-attention. Subsequently, we incorporate the dynamic activation function Meta-ACON within the backbone network to further amplify the network’s ability to depict disease-related features. Finally, we propose an enhanced bidirectional weighted feature pyramid network (IBiFPN) for merging multi-scale features and feeding the feature maps extracted by the backbone network into the multi-scale feature fusion module. This enhancement elevates detection accuracy and effectively mitigates false positives and false negatives arising from overlapping and occluded disease targets within intricate backgrounds. Our approach demonstrates remarkable efficacy, achieving a mean Average Precision (mAP) of 92.3% on a curated dataset, marking an 8.7% point improvement over the baseline method. Additionally, it attains a detection speed of 46.6 frames per second (FPS), adeptly meeting the demands of agricultural scenarios.

Occurrence of Cassava (Manihot esculenta) Leaf Spot Disease Caused by Diaporthe ueckeri in China.

Cassava (Manihot esculenta) is a perennial crop of the family Euphorbiaceae, widely cultivated due to its phytopharmacological and economic values in China. In November 2022, a leaf spot disease on cassava was observed in Zhanjiang, Guangdong, China (21.17° N, 110.18° E), with 100% disease incidence. About 80 % of leaves were covered with spots on the infected plants. Typical symptoms initially appeared as irregular water-soaked lesions that became brown and whitish with the progress of the disease, lesions gradually expanded and coalesced, causing leaf withering, drying and final fall. Tissues (4 to 5 mm) were excised from the margin of lesions, sterilized in 3% H2O2 solution for 3 min, rinsed three times with sterile water, placed on potato dextrose agar (PDA) medium (containing 50mg/L penicillin), and incubated at 25-28 °C. Ten single hypha isolates with similar morphology were obtained and further purified as single conidium subcultures. The colony was grey whitish with sparse aerial mycelium and colony diameter reached 70.4 mm after four days incubation at 25-28℃ in the dark. Black pycnidia occurring as clusters were spherical or irregular, erumpent at maturity, often with a creamy whitish, conidial cirrus extruding from ostiole after 30-days incubation. Conidiophores were hyaline, smooth, unbranched. Alpha conidia were bi-guttulate, hyaline, ellipsoidal, aseptate, with dimensions of 5.1~7.5×1.9~3.4µm (mean 6.2×2.8 µm, n>50). Beta conidia were abundant, filiform, hyaline, smooth, curved in a hooked shape, with a truncate base and dimensions of 18.5-26.4 × 0.6-1.2μm (mean 23.4 × 1.0 μm, n= 40) . Gamma conidia were not observed. The morphological characteristics were similar to those of Diaporthe ueckeri (Udayanga et al. 2015). The internal transcribed spacer (ITS) region, large subunit (LSU) rRNA sequence, actin (ACT), calmodulin (CAL), histone H3 (HIS), translation elongation factor 1-alpha (TEF1-α), and β-tubulin (TUB) genes of a representative isolate CCAS-MS-6 (ACCC 35497) were amplified and sequenced using primer pairs: ITS5/ITS4, LR0R/LR5, ACT-512F/ACT-783R, CAL228F/CAL737R, CYLH3F/ H3-1b, EF1-728F/ EF1-986R and Bt2a/Bt2b (Gao et al 2017；Udayanga et al 2014). All sequences were deposited in GenBank (OR361671, OR361672, and OR365605-9). BLAST search showed high similarities with sequences of Diaporthe ueckeri (Tab 1). Maximum likelihood analyses of the concatenated data of CAL, HIS, ITS, TEF and TUB using Mega 11 placed CCAS-MS-6 in the D. ueckeri clade. Thus, the fungus was identified as D. ueckeri. Three one-year old healthy plants were used for pathogenicity tests in pots. Two 15-day old leaves of each plant were cleaned with 75% alcohol, three sites on each leaf were wounded, and sites on one of the leaf were covered with fungal plugs from 15-day-old cultures on PDA, and sites on the other leaf with PDA plugs as a control. All plants were kept at ambient temperature (about 28℃) and covered with plastic bags containing sterile wet cotton to maintain the humidity. Seven days after inoculation, all inoculated sites showed symptoms of necrosis, while control sites showed no symptoms. The same fungus identified on the basis of morphological and molecular criteria was reisolated from symptomatic inoculated leaves. In China, D. ueckeri had been reported to cause diseases on Eucalyptus citriodora, Camellia sinensis, and Michelia shiluensis (Gao et al 2016; Liao et al 2023; Yi et al 2018), this is the first report on M. esculenta. The definition of the disease etiology is a prerequisite to develop effective management strategies.

New records of Pestalotioid species associated with leaf spot disease on Camellia sinensis from northern Thailand

Camellia sinensis (L.) Kuntze var. assamica (Miang tea) is widely distributed in northern Thailand due to its traditional and industrial attributes, including black tea and Miang production. In this study, two Pestalotioid taxa associated with C. sinensis leaf spots were collected in Mae Taeng district, Chiang Mai Province, Thailand. Species delineation was based on the evidence from morphological and multi-locus phylogenies using ITS, tub2 and tef1-α. Neopestalotiopsis saprophytica is herein reported as a new record on Camellia sinensis, while Pseudopestalotiopsis chinensis is recorded as a new geographical record from Thailand. The findings of this research have the potential to offer fresh insights into the two previously documented species within the existing fungal community associated with C. sinensis in Thailand. This, in turn, could enhance our comprehension of their interactions with the host plant in the times ahead.

Plant density and variety effect on yield, leaf spot disease, weed species richness and diversity of groundnut production in northern Ghana

AbstractLow plant density and weed infestation are major challenges for groundnut production in northern Ghana. A two‐year on‐farm study was conducted to determine the effect of plant density and variety on grain and fodder yields, incidence of leaf spot disease, weed species diversity and biomass. A factorial treatment combination of 6 varieties and 4 plant densities laid in strip plot design with 4 replications was used. The varieties were (early maturity type: Chinese, Yenyewoso, Samnut 23 and late maturity type: Azivivi, Manipinta, Samnut 22). The plants density included 9, 11, 15 and 22 plants/m2. The late maturity varieties recorded higher (p < .05) canopy cover, grain and fodder yields relative to that of the early maturity varieties. The late maturity varieties also recorded the least sedge weed species frequency, density and incidence of leaf spot disease compared with that of the early maturity varieties. The canopy cover, grain and fodder yields increased with increasing plant density. Broadleaf weed species frequency and density, weed biomass, richness, and diversity declined with increasing plant density. Grain yield showed negative and significant correlation with broadleaf weed species frequency, density and weed biomass. The results suggest that both early and late maturity groundnut varieties can be planted at a density of 22 plants/m2 to increase grain and fodder yields and reduce weed species richness, diversity and growth in northern Ghana and similar agro‐ecology in West Africa.

Cercospora leaf spot detection in sugar beets using high spatio-temporal unmanned aerial vehicle imagery and unsupervised anomaly detection methods

Cercospora leaf spot detection in sugar beets using high spatio-temporal unmanned aerial vehicle imagery and unsupervised anomaly detection methods

First report of leaf spot on Daphniphyllum macropodum caused by Neopestalotiopsis clavispora in China.

Daphniphyllum macropodum Miq., an evergreen arbor, is widely cultivated in southern China for its ornamental and medicinal value (Su et al. 2013). In October 2019, a severe leaf spot was observed on D. macropodum in Jinggangshan National Nature Reserve in Ji'an city, Jiangxi, China (114°06'23″E, 26°32'25″N). The plants were about 15 years old, and the disease incidence was estimated to be 15% (4/26 plants). The disease primarily appeared as small black spots on the leaves. At the late stage, the spots enlarged and coalesced into regular or irregular gray necrotic lesions with dark margins. We collected five samples per plant and total 20 samples were collected to isolated the pathogen strains. The margin of the diseased tissues was cut into 5 mm × 5 mm pieces; surface disinfected with 70% ethanol and 2% NaOCl for 30 s and 60 s, respectively; and rinsed thrice with sterile water. Tissues were placed on potato dextrose agar (PDA) and incubated at 25°C in the dark. Pure cultures were obtained by single-spore isolation method, and the representative isolates, JRM3, JRM6, and JRM8 were used for morphological studies and phylogenetic analyses. The colonies of three isolates grown on PDA were white, cottony, and flocculent, contained undulate edges with dense aerial mycelium on the surface at 25 °C. Conidiomata was black conidial masses on PDA. Conidia were 5-celled, clavate to fusiform, smooth, 19.3 to 24.4 long × 6.1 to 8.6 μm wide (n = 50). The 3 median cells were dark brown to olivaceous, the central cell was darker than the other 2 cells, and the basal and apical cells were hyaline. All conidia developed one basal appendage (3.4 to 8.3 μm long; n = 50), and 2 to 3 apical appendages (18 to 32 μm long; n = 50), filiform. The morphological characteristics of the isolates are comparable with those of the genus Neopestalotiopsis (Maharachchikumbura et al. 2014). The internal transcribed spacer (ITS) regions, β-tubulin 2 (TUB2) and translation elongation factor 1-alpha (TEF1-α) were amplified from genomic DNA for the three isolates using primers ITS1/ITS4, T1/Bt-2b, EF1-728F/EF-2 (Maharachchikumbura et al. 2014), respectively. The sequences of the isolates were submitted to GenBank (ITS, OQ372202 to OQ372204; TUB2, OQ390129 to OQ390131; TEF1-α, OQ390126 to OQ390128). A maximum likelihood and Bayesian posterior probability analyses using IQtree v. 1.6.8 and Mr. Bayes v. 3.2.6 with the concatenated sequences placed JRM3, JRM6, and JRM8 in the clade of N. clavispora. Based on the multi-locus phylogeny and morphology, three isolates were identified as N. clavispora. To confirm pathogenicity, eight healthy 10-year-old D. macropodum plants growing in the field were chosen, and 4 leaves per plant were wounded with a sterile needle and inoculated with 10 μL conidial suspension per leaf (106 conidia/ml). Eight plants inoculated with sterile water were used as control. All the inoculated leaves were covered with plastic bags to maintian a humidity environment for 2 days. The leaves inoculated with conidial suspension showed similar symptoms to those observed in the field, whereas control leaves were asymptomatic for 10 days. The same fungus were re-isolated from the lesions, whereas no fungus was isolated from control leaves. N. clavispora was determined as the pathogen of a variety of plant diseases, including Kadsura coccinea (Xie et al. 2018), Dendrobium officinale (Cao et al. 2022), Macadamia integrifolia (Santos et al. 2019). However, this is the first report of N. clavispora infecting D. macropodum in China. This work provided crucial information for epidemiologic studies and appropriate control strategies for this newly emerging disease.

In vitro, in planta, and comparative genomic analyses of Pseudomonas syringae pv. syringae strains of pepper (Capsicum annuum var. annuum).

Pseudomonas leaf spot (PLS) caused by Pseudomonas syringae pv. syringae (Pss) causes significant losses to the pepper industry. Highly virulent Pss strains under optimal environmental conditions (cool-moderate temperatures, high moisture) can cause severe necrotic lesions on pepper leaves that consequently can decrease pepper yield if the disease persists. Hence, it is important to understand the virulence mechanisms of Pss to be able to effectively control PLS in peppers. In our study, in vitro, in planta, and whole-genome sequence analyses were conducted to better understand the virulence and pathogenicity characteristics of Pss strains in peppers. Our findings fill a knowledge gap regarding potential virulence and pathogenicity characteristics of Pss in peppers, including virulence and antimicrobial gene content. Our study helps pave a path to further identify the role of specific virulence genes in causing disease in peppers, which can have implications in developing strategies to effectively control PLS in peppers.

Assessing the efficiency of UAV for pesticide application in disease management of peanut crop.

Effective utilization of plant protection UAVs in peanut cultivation management necessitates a comprehensive grasp of how application volume rates and pesticides influence peanut leaf spot and rust control. This study aimed to compare the effects of application volume rates and pesticides on droplet deposition, disease, leaf retention rate, and peanut yield. A T20 plant protection UAV sprayer was used to apply four various pesticide doses. In comparison, a knapsack sprayer was used to spray with an application volume rate of 450 L/ha. The results showed a significant difference in droplet deposition between the plant protection UAVs and the electric knapsack sprayer. In the pesticide treatment with an application volume rate of 15.0 L/ha, there was no significant difference in the deposition on the peanut canopy of each pesticide treatment, but there was a significant difference in the deposition on the ground in the treatment with adding vegetable oil adjuvant. The treatment with added vegetable oil additives showed the worst performance. The treatment with a spray volume of 22.5 L/ha showed the best performance, with only the leaf spot control effect being 0.3 percentage points lower than that of the electric knapsack sprayer. Plant protection UAV spraying is feasible to control peanut diseases. Considering the operational effectiveness of the plant protection UAV and application volume rate, it is recommended to use a spray volume of 22.5 L/ha without adding vegetable oil adjuvants for field operations. This article is protected by copyright. All rights reserved.

Cultural, Morphological and Pathogenic Variability in the Colletotrichum capsici Isolates, Inciting Anthracnose and Fruit rot of Chilli (Capsicum annuum L.) in different Agro-Climatic Zones of Kerala, India

Aims: To study the cultural, morphological and pathogenic variability existing among the pathogen isolates of Colletotrichum capsici, inciting anthracnose and fruit rot of chilli in Kerala. Study Design: Completely randomized design (CRD). Place and Duration of Study: Department of Plant Pathology, College of Agriculture (Kerala Agricultural University), Vellayani, Thiruvananthapuram during 2018-2019. Methodology: A survey was conducted in the five agro-climatic zones (ACZs) of Kerala viz., Northern zone, Central zone, Special problem zone, High range zone and Southern zone to assess the incidence and severity of anthracnose disease. The various symptoms in the surveyed locations were also noted. Pathogen isolates were grown in PDA medium in the laboratory and colony characters (colour and mycelial growth rate of pathogen colonies) were observed. Also, the morphological characters viz., mycelial width, shape and size of conidia, acervular diameter, number and size of setae, appressorial size were recorded. Results: Maximum anthracnose incidence of 90 per cent and severity of 52.60 per cent were noticed at Regional Agricultural Research Station (RARS), Pilicode (Northern zone). Characteristic leaf spot, fruit rot and die-back symptoms were observed in the survey locations. Pathogen colonies showed different shades of white, off-white to grey turning brown or black with regular or irregular margins and concentric rings of black acervuli in the potato dextrose agar (PDA) medium. The diameter of growth of C. capsici isolates ranged from 7.20 to 8.60 cm at 7 days after incubation. All the C. capsici isolates initiated hyaline mycelium having a width of 1.73 - 2.36 µm and produced numerous sickle shaped conidia with a size range of 19.42 - 20.46 µm × 2.16 - 3.09 µm. Black coloured, circular or ellipsoidal acervuli (122.14 - 189.08 µm dia.) had 20 – 46 setae of length 74.13 to 107.30 µm. Also, brown or black appressoria of size 8.64 - 12.64 µm × 5.54 - 7.84 µm were formed in slide culture. Cc3 from College of Agriculture, Vellanikkara was obtained as the most virulent isolate producing a lesion size of 1.13 cm and PDI of 45.33 in the artificially inoculated chilli fruits (var. Vellayani Athulya) at 5 days after inoculation. Conclusion: All the nine C. capsici isolates exhibited variability in their cultural, morphological and pathogenic characteristics. Variability in phytopathogenic fungi helps in identifying novel and sustainable control methods to tackle the diseases incited by them. Understanding pathogen variability provides new insights for developing effective disease management methods. This will help in promoting sustainable agriculture and preventing severe crop losses.

In-vitro Efficacy of Different Chemical Fungicides and Plant Extracts Against Alternaria alternata Causing Alternaria Leaf Spot Disease in Brinjal

Five different chemical fungicides and three plant extracts were evaluated against Alternaria alternate causing Alternaria leaf spot disease in brinjal. The experiment was carried out in the laboratory of plant pathology at Chaudhary Charan Singh University Meerut, during kharif season 2021-22. During survey the maximum disease incidence was recorded (37.8%) Rajpura in Meerut and minimum (10.9%) incidence was recorded in Lakhaoti, survey and metrological data presented in the (Tables 2 & 3). The incidence of the disease varied from 10.9 to 37.8 percent due to difference in environmental condition. The concentration of all fungicides and Plant-extracts was kept at 500, 1000 and 2000 ppm.  Mycelial growth was measured to continue zero to ten days. Mainly four chemical fungicides (Thaiophinate Methyl 70%WP, Propineb 70% WP, Carbendazim 50%WP and Chlorothalonil 75% WP) and Neem extract significantly inhibited the mycelial growth of the pathogen (Alternaria alternata). Among all those, four fungicides and Neem extract giving the better results. Maximum 100% mycelial growth inhibition was recorded in Thaiophinate Methyl 70%WP, 94.45% mycelial growth inhibition was recorded in Propineb 70% WP, 86.09% mycelial growth inhibition was recorded in Carbendazim 50%WP and 84.80 growth inhibition was recorded in Chlorothalonil 75% WP and in plant extract 18.53% inhibition was observed in Neem and 14.33% inhibition was observed in garlic. However, Azoxystrobin 23% SC and Onion also had some effect, which is mentioned in the result of the paper.

Maize leaf disease recognition using PRF-SVM integration: a breakthrough technique

The difficulty of collecting maize leaf lesion characteristics in an environment that undergoes frequent changes, suffers varying illumination from lighting sources, and is influenced by a variety of other factors makes detecting diseases in maize leaves difficult. It is critical to monitor and identify plant leaf diseases during the initial growing period to take suitable preventative measures. In this work, we propose an automated maize leaf disease recognition system constructed using the PRF-SVM model. The PRFSVM model was constructed by combining three powerful components: PSPNet, ResNet50, and Fuzzy Support Vector Machine (Fuzzy SVM). The combination of PSPNet and ResNet50 not only assures that the model can capture delicate visual features but also allows for end-to-end training for smooth integration. Fuzzy SVM is included as a final classification layer to accommodate the inherent fuzziness and uncertainty in real-world image data. Five different maize crop diseases (common rust, southern rust, grey leaf spot, maydis leaf blight, and turcicum leaf blight along with healthy leaves) are selected from the Plant Village dataset for the algorithm’s evaluation. The average accuracy achieved using the proposed method is approximately 96.67%. The PRFSVM model achieves an average accuracy rating of 96.67% and a mAP value of 0.81, demonstrating the efficacy of our approach for detecting and classifying various forms of maize leaf diseases.

First Report of Pseudopestalotiopsis ixorae Causing Leaf Spot of Photinia × fraseri in China.

Photinia × fraseri is a well-known ornamental shrub in southern China. In December 2021, we observed leaf spots that were circular to irregular, gray with dark red margins and violet brown with brownish violet edges on the leaves of Photinia × fraseri shrubs in the scenic area of Shenlongtan (28°46'10″N, 115°42'93″E), Jiangxi Province, China. Almost 15% of the leaves in the 1300 m2 Photinia × fraseri planting area were symptomatic. Thirty symptomatic leaves were randomly collected from different plants, and sectioned into 5-mm2 pieces, which were surface-sterilized using 1% NaOCl for 30 s. After rinsing thrice in sterile distilled water and drying, the pieces were transferred onto potato dextrose agar (PDA) and incubated at 28 ℃ for 5-7 days. A total of sixteen morphologically similar isolates were obtained. After incubation on PDA for 20 days, the fungi had irregular edges, were white to pale brown, and had spare aerial mycelium on the surface with irregularly distributed black, gregarious conidiomata. Conidia were fusoid, subcylindrical, straight to slightly curved, 4-septated, slightly constricted at the septa, and 23 to 36 × 6 to 10 μm (mean: 27.6 × 7.7 μm). The morphological characteristics were consistent with the features of Pseudopestalotiopsis species (Maharachchikumbura et al. 2014). The genomic DNA of two representative isolates (JFRL032 and JFRL033) was extracted for further identification. The internal transcribed spacer (ITS) region, translation elongation factor 1-ɑ (tef1-ɑ) and β-tubulin (tub2) genes were amplified and sequenced using primers ITS5/ITS4, EF1-526F/EF1-1567R, and Bt2A/Bt2B, respectively (Maharachchikumbura et al. 2012). The sequences of the two representative isolates were 100% identical to each other. These nucleotide sequences were deposited in GenBank with accession numbers, ON342794 and ON342795 (ITS); ON375851 and ON375852 (tef1-ɑ); ON375853 and ON375854 (tub2). BLASTn searches of the obtained sequences revealed 99%-100% to ITS (MG816316, 478/478 nucleotides), tef1-ɑ (MG816336, 924/926 nucleotides), tub2 (MG816326, 441/442 nucleotides) sequences of the ex-type strain of Pseudopestalotiopsis ixorae (NTUCC17-001.1). Phylogenetic analysis was conducted using the concatenation of multiple sequences (ITS, tef1-ɑ and tub2) with the Maximum likelihood statistics in PhyloSuite v1.2.2 (Zhang et al.2020). The phylogenetic tree showed the two isolates clustered with P. ixorae in a clade with 100% bootstrap support. The isolates were identified as P. ixorae based on morphological and molecular data. To confirm pathogenicity, eight healthy leaves of 3-year-old Photinia × fraseri were surface sterilized, scratched with a pair of sterilized tweezers, and ten µl of conidial suspension (106 conidia/ml) was sprayed on the injured leaves and the control was sprayed with sterile distilled water. Then, All plants were potted in a climate chamber at 25℃ and 85% relative humidity. After 3 days, leaf spot symptoms similar to those described above were observed on inoculated leaves, while the non-inoculated leaves remained symptomless. The pathogen was reisolated from the inoculated leaves to fulfill Koch's postulates and confirmed as P. ixorae by morphological and molecular analysis. It has been reported that P. ixorae can infect the Ixora plant (Tsai et al., 2018). To the best of our knowledge, this is the first report of P. ixorae causing leaf spot on Photinia × fraseri in China. The study provides valuable information for identifying and controlling the leaf spot on Photinia × fraseri.

Development and validation of a standard area diagram set to assess corn grey leaf spot severity and foliar fungicide control efficacy

AbstractGrey leaf spot (GLS), caused by Cercospora spp., has become a very important foliar disease for second‐crop corn season, mainly in South America. Therefore, this study aimed to develop and validate a standard area diagram set (SADs) to estimate the severity of GLS and to apply the SADs established in this study to evaluate the efficacy of fungicides for GLS control in field trials. The SADs with nine levels of severity (0.5; 2; 5; 10; 20; 30; 40; 50 and 60%) improved accuracy, precision and reliability. To evaluate the control of GLS in corn, two experiments spraying chemical fungicides were conducted, one in Rio Verde (GO) (experiment A) and another in Chapadão do Sul (MS) (experiment B). Both experiments were conducted in randomized block design, with 10 treatments and four replicates. For the severity assessment, the SADs elaborated in this study was used. From this severity data over time, disease progress curves, area under the disease progress curve (AUDPC), and yield were obtained. Based on the AUDPC and yield values, all treatments differed from the control. The fungicide fluxapyroxad + pyraclostrobin + mefentrifluconazole had the highest value, giving 72.8% control efficacy and the highest yield maintenance of 43.5%. The other treatments had an intermediate control efficacy and yield. The SADs proposed here is a useful tool for improving visual assessments of GLS severity on corn leaves and fungicides can be used for integrated disease management.

Antifungal Potential of Ocimum sanctum Linn. Essential Oil against Fungal Pathogens Causing Economic Losses in Cymbopogon flexuosus Nees Ex Steud. (Lemongrass)

Cymbopogon flexuosus Nees Ex Steud. (Commonly known as lemongrass, family Poaceae) is one of the commercially important aromatic plants having medicinal properties. India is one of the largest producers and exporters of lemongrass essential oil in the world; in the year 2021-22, India exported about 610 tons of lemongrass oil, contributing more than 4 lakh US $ million in Gross Domestic Productivity (GDP). However, despite a good national and international market, this crop suffers quantitative and qualitative losses due to the leaf spot and leaf blight diseases caused by the fungi Curvularia trifolii and Rhizoctonia solani, respectively; therefore, an attempt has been made to manage these fungal pathogens. The essential oil of basil (Ocimum sanctum Linn.) was extracted by hydro-distillation method using Clevenger apparatus. The oil thus extracted was used for in vitro antifungal efficacy against both the test fungi Curvularia trifolii and Rhizoctonia solani, using the poison food technique. The results show that the minimum inhibitory concentration (MIC) of the basil oil against C. trifolii 2000 ppm and R. solani was 1600 and however, it was cidal in nature at 3200 and 2400 ppm against both fungi, respectively. The current study’s findings show that O. sanctum oil could be an alternative to synthetic fungicides after detailed investigations.