Blight Severity Research Articles

Estimation of blight and spot diseases severity in Ciherang and Ciliwung rice varieties based on vegetation index algorithms

Abstract. Bande LOS, Hasan A. 2024. Estimation of blight and spot diseases severity in Ciherang and Ciliwung rice varieties based on vegetation index algorithms. Biodiversitas 25: 1015-1021. Blight and spot diseases are often associated with rice plant, causing high disease severity and potentially reducing crop production. One effective disease management strategy is using resistant varieties and intensive disease monitoring through camera sensor technology and vegetation index-based image processing. Therefore, this study aimed to assess the severity of blight and spot diseases on two rice plant varieties based on vegetation indexes. Image recording was carried out on rice field and leaf samples of Ciherang and Ciliwung varieties. This was followed by image processing based on normalized difference vegetation index (NDVI) to determine the proportion of sick/healthy plants in the field and dark green color index (DGCI) to quantify disease severity. The results showed that the proportion of healthy plant in Ciliwung rice field was greater than in Ciherang as shown by NDVI. Based on DGCI, Ciliwung also had a relatively lower level of disease severity compared to Ciherang, although the difference was not statistically significant. Blight disease caused more severe damage to rice leaf than spot disease based on image processing results. Furthermore, a positive correlation was observed between the increase in DGCI and NDVI.

A novel biocontrol strain Pseudomonas canadensis FRPC18 against box blight (causative agent Calonectria pseudonaviculata)

BackgroundRecent box blight epidemics caused by Calonectria pseudonaviculata (Cps) have created the need for finding eco-friendly management strategies, especially in natural habitats. In the present research, the biocontrol activity of 26 bacterial isolates against Cps was investigated under laboratory and greenhouse conditions in a completely randomized design (n = 3; P < 0.05).ResultsStrains FRPC18, FRPF4, and FRPF6 showed the most efficiency in the inhibiting Cps colony by 72.4, 46.8, and 34.2% through a dual culture test, respectively. The superior strain, FRPC18, identified belonged to Pseudomonas canadensis. FRPF6 volatile and FRPC18 non-volatile antifungal compounds resulted in the highest inhibition rate of 27.67 and 59.43%, respectively. Strain FRPC18 could also produce the maximum amount of chitinase, significantly, while the highest amount of siderophores was detected in FRPF4. There were non-significant differences among the bacterial strains in producing protease and pectinase. In the greenhouse, FRPC18 reduced box blight severity by 30% and had non-statistically significant differences with Serenade® as a biofungicide (P < 0.05).ConclusionThe results of this study suggest that P. canadensis may be a new biocontrol agent for controlling box blight in disease hotspots during epidemics in boxwood forests.

Efficacy of Azoxystrobin 7.5% and Propiconazole 12.5% SE Against Sheath Blight in Rice

Among the fungal diseases causing significant yield loss in rice, sheath blight caused by Rhizoctonia solani Kuhn is the most important ranked the second most important disease worldwide after blast and a serious threat in rice growing areas of the world and causes more economic yield losses. The field experiment was conducted with seven treatments and replicated three times in RBD design at ARS, Gangavati to know the effect of Azoxystrobin 7.5% + Propiconazole 12.5% SE against sheath blight in rice. The variety BPT-5204 was sown in plot size of 5 X 5 m2 with all regular agronomic practices followed as per the standard package of practice of University of Agricultural Sciences, Raichur. It has been found that the fungicide Azoxystrobin 7.5% + Propiconazole 12.5% SE at different doses evaluated was effective in reducing the severity of rice sheath blight and thereby increased the rice grain yield. The treatment Azoxystrobin 7.5% + Propiconazole 12.5% SE @ 625 ml/ha recorded minimum sheath blight of 13.70 and 16.11 per cent PDI with yield of 64.60 q/ha and 63.20 q/ha compared to control treatment 48.70 and 57.96 per cent PDI with grain yield of 54.10 q/ha and 52.40 q/ha during the first and second season, respectively. In the current study, along with reducing sheath blight severity, fungicide treatments minimized grain yield losses in 2 years. Field trial conducted clearly indicated that Azoxystrobin 7.5% + Propiconazole 12.5% SE @ 500 and 625 ml/ha dose can effectively control sheath blight of rice. Azoxystrobin 7.5% + Propiconazole 12.5% w/v SE @ 500 ml/ha was at par with higher dose and resulted better yield than other treatments.

Enhanced control efficacy of Bacillus subtilis NM4 via integration of chlorothalonil on potato early blight caused by Alternaria solani

Early blight caused by Alternaria solani is a common foliar disease of potato around the world, and serious infections result in reduced yields and marketability due to infected tubers. The major aim of this study is to figure out the synergistic effect between microorganism and fungicides and to evaluate the effectiveness of Bacillus subtilis NM4 in the control of early blight in potato. Based on its colonial morphology and a 16S rRNA analysis, a bacterial antagonist isolated from kimchi was identified as B. subtilis NM4 and it has strong antifungal and anti-oomycete activity against several phytopathogenic fungi and oomycetes. The culture filtrate of strain NM4 with the fungicide effectively suppressed the mycelial growth of A. solani, with the highest growth inhibition rate of 83.48%. Although exposure to culture filtrate prompted hyphal alterations in A. solani, including bulging, combining it with the fungicide caused more severe hyphal damage with continuous bulging. Surfactins and fengycins, two lipopeptide groups, were isolated and identified as the main compounds in two fractions using LC-ESI-MS. Although the surfactin-containing fraction failed to inhibit growth, the fengycin-containing fraction, alone and in combination with chlorothalonil, restricted mycelial development, producing severe hyphal deformations with formation of chlamydospores. A pot experiment combining strain NM4, applied as a broth culture, with fungicide, at half the recommended concentration, resulted in a significant reduction in potato early blight severity. Our results indicate the feasibility of an integrated approach for the management of early blight in potato that can reduce fungicide application rates, promoting a healthy ecosystem in agriculture.

Genetic structure and population diversity of Phytophthora infestans strains in Pacific western Canada

Late blight caused by Phytophthora infestans is an economically important disease of potato and tomato worldwide. In Canada, an increase in late blight incidence and severity coincided with changes in genetic composition of P. infestans. We monitored late blight incidence on tomato and potato in Pacific western and eastern Canada between 2019 and 2022, identified genotypes of P. infestans, and examined their population genetic diversity. We identified four major existing genotypes US11, US17, US8, and US23 as well as 25 new genotypes. The US11 genotype was dominant in Pacific western Canada, accounting for 59% of the total population. We discovered the US17 genotype for the first time in Canada. We revealed a higher incidence of late blight and quite diverse genotypes of P. infestans in Pacific western Canada than in eastern Canada. We found high genetic diversity of P. infestans population from Pacific western Canada, as evidenced by the high number of multilocus genotypes, high values of genetic diversity indices, and emergence of 25 new genotypes. Considering the number of disease incidence, the detection of diverse known genotypes, the emergence of novel genotypes, and the high number of isolates resistant to metalaxyl-m (95%) from Pacific western Canada, the region could play a role in establishing sexual recombination and diverse populations, which could ultimately pose challenges for late blight management. Therefore, continuous monitoring of P. infestans populations in Pacific western region and across Canada is warranted.Key points• Genotypes of P. infestans in Pacific western were quite diverse than in eastern Canada.• We discovered US17 genotype for the first time in Canada and identified 26 novel genotypes.• Approximately 95% of P. infestans isolates were resistant to metalaxyl-m.

Fusarium head blight detection, spikelet estimation, and severity assessment in wheat using 3D convolutional neural networks

Fusarium head blight (FHB) is one of the most significant diseases affecting wheat and other small grain cereals worldwide. Developing FHB-resistant cultivars is critical but requires field and greenhouse disease assessment which are typically laborious and time-consuming. In this work, we developed automated applications based on 3-dimensional (3D) convolutional neural networks (CNN) that detect FHB symptoms expressed in wheat, estimate the total number of spikelets versus the total number of infected spikelets on a wheat head, and subsequently calculate FHB severity index. Such tools are an important step toward the creation of automated and efficient phenotyping methods. The data used to generate the results are 3D point clouds consisting of four color channels – red, green, blue (RGB), and near-infrared (NIR) – collected using a multispectral 3D scanner. Our 3D CNN models for FHB detection achieved 100% accuracy. The influence of the multispectral information on performance was evaluated; the results showed the dominance of the RGB channels over both the NIR (720 nm peak wavelength) and the NIR plus RGB channels combined. Our best 3D CNN models for estimation of total and infected number of spikelets achieved mean absolute errors (MAE) of 1.13 and 1.56, respectively. Our best 3D CNN models for FHB severity estimation achieved 8.6 MAE. A linear regression analysis between the visual FHB severity assessment and the FHB severity predicted by our 3D CNN showed a significant correlation.

Prevalence of Rice Sheath Blight Disease in Cauvery Command Area of Karnataka, India

Among the various disease of rice, sheath blight caused by Rhizoctonia solani Kuhn has become one of the major fungal diseases covering different rice growing ecosystem of Cauvery command area of Karnataka. Roving disease survey was conducted during Kharif-2022 to know the occurrence and spread of sheath blight disease in Cauvery command area of Karnataka i.e. Mandya, Hassan, Mysuru and Chamarajnagara. Among the four districts surveyed, disease severity (%) was found highest in Hassan district with a mean disease severity of 22.86% which is followed by Mandya (19.90%), Mysuru (19.39%) and least disease severity was recorded in Chamarajnagara (12.54%). The high severity of sheath blight might be due to the highly favourable factors like high relative humidity, less temperature and water stagnation in these locations during the period of survey. Large scale cultivation of susceptible varieties as mono crop continuously on the same field might have increased the possibility of perpetuating the pathogen in the crop debris. This study can serve as basic to evaluate location specific integrated disease management strategy against sheath blight disease of rice.

New Potato Varieties Resistant to Late Blight and with High Quality for French Fries Generated in Peru

Potato is one of the main crops worldwide and generates income for small-scale farmers, and it is a primary component of the diet of rural inhabitants, especially in developing countries. In Peru, the demand for French fries in traditional restaurants, rotisserie chicken (“Pollerias”), and fast-food restaurants is increasing every day. However, supply is covered by imported pre-fried potatoes. During the 2019–2020 and 2020–2021 growing seasons, ten potato clones belong to the International Potato Center (CIP) breeding program, and two Peruvian varieties used for frying as controls UNICA (CIP392797.22) and INIA 303-CANCHAN (CIP380389.1) were tested in 13 trials in farmers' fields placed in the north, center, and south of Peru using a randomized complete block design with three replications of 150 plants. Late blight severity and yield were evaluated under field conditions, and the contents of dry matter and reducing sugars were determined with laboratory tests. Clones CIP395123.6, CIP396026.101, and CIP396034.103 were selected for their high level of resistance to late blight, yields over 30 t/ha, with more than 20% dry matter, less than 0.20% reducing sugars and excellent quality for French fries’ sticks. Selected clones have been registered in the official register of cultivars of Peru, as new varieties. The standard of living of small and medium-scale potato farmers can be improved with the production of these new varieties, which support the health of producers and consumers and the environment. New potato varieties can be used as parents in breeding programs around the world.

Effect of Weather Factors on Severity of Early Blight Incited by Alternaria solani (Ellis and Martin) Jones and Grout in Potato

A study was conducted to find out the influence of weather factors, temperature, relative humidity, bright sunshine hour, rainfall, evaporation and wind speed and spore load on the incidence of Alternaria solani (Ellis and Martin) Jones and Grout induced early blight of potato (Solanum tuberosum L.) during 2019 to 2022. Eight weather factors taken from the agrometeorological observatory located at Anand Agricultural University, Anand, Gujarat, India, and were subjected to correlation analysis. The relationship between early blight and concerned weather parameters during Rabi 2020-21 revealed a highly significant positive correlation with evaporation (0.87) and maximum temperature (0.84) at the 0.01 level. PDI was significantly positively correlated with spore load (0.71) and bright sunshine hour (0.64) at the 0.05 level. Whereas Per cent Disease Intensity was negatively correlated with evening humidity (-0.78) at a 0.01 level. During the year Rabi (winter) 2021-22, a substantial negative correlation with evening humidity at the 0.05 level. PDI was positively correlated with spore load (0.79), bright sunshine (0.73) and evaporation (0.68).

Chemical composition, antioxidant properties, and antifungal activity of wild Origanum elongatum extracts against Phytophthora infestans.

Phytophthora infestans, the causative agent of late blight disease, has gained notoriety for its destructive potential, leading to substantial losses in potato yields. Although conventional systemic fungicides have been shown to be effective in controlling plant pathogens, growing environmental concerns have prompted the need for more integrated disease management approaches. Hence, in this study, the effectiveness of wild Origanum elongatum extracts as biopesticides was explored in controlling P. infestans and potentially mitigating its devastating impact in planta. The aerial parts of O. elongatum were subjected to sequential extraction using water, hexane, chloroform, and methanol. The obtained extracts were tested in vitro through the poisoned food procedure for their capacity to obstruct P. infestans growth and to defeat potato blight severity in vivo. The phyto-contents (total phenolic content (TPC) and total flavonoid content (TFC)), as well as the antioxidant activities, were spectrophotometrically determined in all extracts, and the phytoconstituents of the most active extract (methanolic extract) were profiled via high-performance liquid chromatography-photodiode array-tandem mass spectrometry (HPLC-PDA-MS/MS). In vitro, the complete inhibition rate of the P. infestans was obtained using the methanolic extract at 5 mg/mL, followed by the hexane and chloroform extracts at 10 mg/mL. Interestingly, complete inhibition of the pathogen was achieved upon the application of the aqueous extract at 10 mg/mL. In vivo, the aqueous extract at 25 mg/mL reduced the P. infestans severity rate to 27.25%, while the methanolic extract at 20 mg/mL led to the lowest severity rate. Moreover, the hexane and chloroform extracts impaired the pathogen severity rate to 50% and 41% using 20 mg/mL, respectively. The TPC and TFC in the extracts were variable with high concentrations detected in the methanolic extract with 485.42 mg GAE/g and 58.24 mg QE/g, respectively. In addition, the methanolic extract showed the highest antioxidant activities, while the chloroform extract exhibited the lowest activity. Liquid chromatography (LC)-MS/MS analysis of the methanol extract revealed 56 components from diverse classes. These included organic acids, phenolic acids, flavonoids, tannins, and coumarins. These findings suggest that O. elongatum could be investigated as a potential source of antifungal compounds targeting different phytopathogens.

Effect of Application of Endophytic Bacteria on the Development of Bacterial Leaf Blight Disease, Growth, and Production of Rice Plants

Bacterial leaf blight can be found in various stages of rice plant growth, so this disease can affect the growth and production of rice plants. This research aims to determine the effect of applying an endophytic bacterial formula to rice seedlings on the development of HDB disease, growth, and production of rice plants. This study used 4 isolates of endophytic bacteria (isolates BE-KH1, BE-M2, BE-M3, and BE-S5) which were formulated in coconut water waste + peptone. The results of the study showed that the application of the endophytic bacterial formula to rice seedlings was able to reduce the severity of bacterial leaf blight by 54,5 – 63,2% and had an effect on growth, full grain weight, and rice grain weight in rice plants inoculated with Xanthomonas oryzae pv. oryzae bacteria.

Strategy For Controlling Bacterial Leaf Blight (Xanthomonas sp.) on Eucalyptus Pellita Plants by Administering P. aeruginosa RE081

The demand for Eucalyptus Pellita seeds as a high-throughput inoculum (HTI) crop commodity in the field is extremely high. However, Xanthomonas sp., a bacteria that causes bacterial leaf blight, poses a significant challenge in ensuring a steady supply of healthy seedlings in nurseries. Researchers have explored using the rhizobacteria P. aeruginosa RE081 as an environmentally friendly biocontrol agent to address this issue. This study aims to determine the optimal concentration of P. aeruginosa RE081 that can effectively reduce the incidence and severity of bacterial leaf blight caused by Xanthomonas sp. The research was conducted using a completely randomized design, with different concentrations of P. aeruginosa RE081 (105, 106, 107, 108 CFU/mL) being tested. The findings indicate that the biological agent's concentration significantly impacts plant disease occurrence and severity. In vivo testing revealed that P. aeruginosa RE081 reduced disease severity by only 2.13% at a 108 CFU/mL concentration. Interestingly, concentrations lower than 108 CFU/mL increased disease severity compared to the control group.

Controlling Fusarium head blight in wheat through a Mixture of varieties in an organic production system

In the organic production system, the management of diseases and pests is based on agricultural practices rather than the use of certified phytosanitary inputs. The mixture of varieties is an agricultural practice that has shown its interest not only in the management of diseases and pests but also in the increase and stability of crop yields. The objective of our study is to evaluate the performance of this practice in the management of fusarium head blight in wheat. To achieve this objective, we conducted four trials. Two trials (one on durum and the other on soft wheat) in 2019 on a certified organic farm and the two trials were repeated in 2020. During the two years of experimentation, we compared the mixture of four durum wheat varieties and the mixture of four soft wheat varieties with the monoculture varieties. In the field, we evaluated the severity of Fusarium head blight and wheat yield components as well as the grain yield. The results showed a significant difference between the different treatments for Fusarium head blight severity and yield components for both species and in both years of the experiment.

Silicon Supplements Potentially Reduce the Sheath Blight Incidence and Severity of Rice (Oryza sativa L.)

Sheath Blight is a disease causing up to 50% yield losses of rice depending on severity. Silicon (Si) is a beneficial nutrient for rice having the ability to protect against diseases. So, a pot experiment was carried out at the Bangladesh Institute of Nuclear Agriculture Headquarters Farm, Mymensingh from July 2021 to November 2021 with artificial inoculation of Rhizoctonia solani to study the effect of different Si supplements and their doses on rice ShB incidence and severity. The test crop used in the study was Chinigura aromatic rice variety. The experiment was laid out in a completely randomized design (CRD) with three replications. Among the nine treatments, except control, Si was applied from K2SiO3, CaSiO3, and MgSiO3 with three concentrations viz., 2, 4, and 6 mM Si respectively through the foliar spray. The application of different Si supplements showed a significant positive effect on the growth, yield contributing characters, and yield of rice. The highest yield was found at the application of Si as CaSiO3 6 mM. Disease incidence and severity matrix were significantly reduced due to the application of different Si supplements. The minimum disease incidence and severity matrix were found at T6 (CaSiO3 6 mM) treatment. The maximum disease incidence and severity matrix reduction was 35.27% and 54.3%, respectively at T6 (CaSiO3 6 mM) treatment over control (without Si application) which was statistically identical to T3 (K2SiO3 6 mM), T7 (MgSiO3 2 mM), and T8 (MgSiO3 4 mM). The overall disease incidence and severity matrix reduction over control was 24.68% and 35.59%, respectively due to different Si supplement applications. Again, the highest nutrient concentration was found in different Si supplement treatments over control. So, Si supplement applications such as K2SiO3, CaSiO3, and MgSiO3 may be an advisable option for the management of sheath blight disease of rice for successful crop production.

Field efficacy of Gliding Arc Plasma Activated Water and natural products on tomato (Solanum lycopersicum L.) late blight [Phytophthora infestans (Mont.) de Bary] severity

Abstract This study aimed to evaluate the field efficacy of plasma-activated water (PAW) as a novel technology in agriculture together with vinegar, sodium bicarbonate, and plant aqueous extracts against tomato late blight in a complete randomised block design. Ten treatments were evaluated: Plasma activated water (PAW), a mixture of sodium bicarbonate and vinegar at different ratios (25/75, 50/50 and 75/25) and different mixtures of aqueous plant extracts made up of ten plants: Ageratum conyzoides, Eucalyptus saligna, Azadirachta indica, Panax quinquefolius, Callistemon viminalis, Euphorbia hirta, E. cordifolia Laggera pterodonta, Ocimum gratissimum and avocado pit powder. Plantizeb and distilled water were used as positive and negative controls, respectively. There was a significant difference (p &lt; 0.05) in the growth variables between treatments at 10 weeks after transplanting (WAT). All the treatments reduced late blight severity compared to the negative control (100 %) at 10 WAT. Late blight severity on plants treated with Plantizeb, PAW, the mixture of bicarbonate and vinegar (B+V) at 50/50 (33.24 %) and the mixture of E. hirta + E. cordifolia extract (33.33 %) was the lowest and significantly comparable (p &lt; 0.05) to Plantizeb (31.67 %). Tomato yield was 2.24 t/ha (negative control), 28.56 t/ha (Plantizeb), 27.23 t/ha (PAW), 30.32 t / ha (B+V at 50/50), and 27.69 t/ha (mixture of the aqueous extract of E. hirta + E. cordifolia). The PAW, the mixtures between B+V at 50/50, and the aqueous extract of E. hirta and E. cordifolia could be exploited for their bioactivity in late blight management in field conditions.

Diagrammatic scale to quantify the severity of Ascochyta blight in broad bean crops

The objective of this study was to design and validate a diagrammatic severity scale of brown spot on broad bean. We collected 120 leaflets with different level of brown spot damage from commercial crops in the Toluca Valley, which were visually selected based on the expressed symptomology. Sixty leaflets were scanned for evaluation with the software APS PRESS ©Assess 2.0 to determine the real severity value for each leaflet. The damage values allowed us to generate a diagrammatic scale consisting of six different classes: 0(0.0), 1(0.1-6.0), 2(6.1-10.0), 3(10.1-15.0), 4(15.1-40.0), 5(&gt; 40.1-100). The leaflets were visually examined by evaluators who had no prior experience. The results from each evaluator were analyzed with a simple linear regression, obtaining r2 values from 0.0042 to 0.8748, β0 de 0.51 a 9.11, y β1 de 0.132 a 0.925. Using a scale, r2 values were obtained 0.9143 to 0.985, β0 de 0.001 a 0.911 y β1&lt;0.001. The generated diagrammatic severity scale was validated and reproducible, showing high reliability.

Present status of major diseases of sunflower in Northern East Dry Zone of Karnataka

A Fixed plot survey was conducted to assess the severity of Alternaria leaf blight, Sunflower necrosis disease, Powdery mildew and Sunflower leaf curl disease during Rabi 2020-21 and Kharif 2021 in Raichur, Koppal and Gulbarga districts of North Eastern Karnataka. The survey results revealed that disease severity was noticed in all locations surveyed. In surveyed area, the PDI of Alternariaster leaf spot was ranged from 42.2 % to 72.8 %. Sunflower necrosis disease incidence ranged from 3.5 to 21.9%.Whereas, during rabi 2020-21 powdery mildew PDI ranged between 30.0 to 75 per cent and leaf curl ranged between 0 to 18.7 per cent in three districts surveyed.

Evaluation of Camellia Cultivars and Selections for Growth, Cold-hardiness, Flowering, and Disease Resistance in Tennessee, USA

Susceptibility to low-temperature injury and diseases is a major concern associated with ornamental camellia production. To comprehensively understand their growth, cold-hardiness, flowering, and disease resistance, 24 camellia (Camellia spp. and hybrids) cultivars and selections were evaluated in McMinnville, TN, USA (USDA plant hardiness zone 7a). During Mar 2011, camellias were planted in the field plots. Plant height and canopy width were measured annually from 2011 to 2019, and low-temperature damage was recorded in 2014 and 2023. The flowering duration was recorded each year from 2011 to 2020. The Camellia Yellow Mottle Virus, monochaetia leaf spot (Monochaetia sp.), edema, flower blight (Ciborinia camelliae), and flower spot (Botrytis cinerea) severity (% affected) were evaluated from Oct to Nov in 2016 and 2017. The season-long area under the disease progress curve (AUDPC) was calculated. Cultivars Arctic Snow and Pink Icicle exhibited the greatest height, and Autumn Spirit, Elaine Lee, Arctic Snow, and Survivor had the widest canopy width, whereas Shishigashira had the lowest height and canopy width. ‘April Remembered’, ‘April Rose’, ‘Arctic Snow’, ‘Ashton’s Ballet’, ‘Autumn Carnival’, ‘Autumn Spirit’, ‘Elaine Lee’, ‘Survivor’, and C. chekiangoleosa selection were least affected by winter low temperatures, whereas ‘Korean Snow’, ‘One Alone’, C. sasanqua selection, ‘Pink Icicle’, and ‘Shishigashira’ were severely damaged. ‘Arctic Snow’ flowered most reliably (6 of 8 years), whereas ‘April Remembered’, ‘April Rose’, ‘Ashton’s Ballet’, ‘Autumn Spirit’, and ‘Survivor’ flowered five times. ‘Korean Fire’, ‘Classic Pink’, ‘Maroon Mist’, and ‘Spring’s Promise’ displayed the highest virus severity and AUDPC. ‘Arctic Snow’, C. sasanqua selection, and the C. chekiangoleosa selection had no viral symptoms. C. sasanqua selection and ‘Red Aurora’ were significantly impacted by edema disorder, with severity ratings of ∼43% and 26%, respectively. Monochaetia leaf spot severity was highest in ‘Red Aurora’ and ‘Spring’s Promise’, whereas ‘Anacostia’, ‘Arctic Snow’, ‘Ashton’s Ballet’, ‘Autumn Spirit’, ‘Classic Pink’, ‘Kuro Delight’, ‘One Alone’, ‘Pink Icicle’, ‘Shishigashira’, and ‘Survivor’ exhibited the least monochaetia leaf spot severity and AUDPC. Flower blight and flower spot were observed only in ‘Arctic Snow’ and ‘Survivor’. These findings will aid landscapers and nursery growers with selecting and managing camellia cultivars effectively.

A Genome-Wide Association Study of Nigerien and Senegalese Sorghum Germplasm of Exserohilum turcicum, the Causal Agent of Leaf Blight

In Senegal, sorghum ranks third after millet and maize among dryland cereal production and plays a critical role in the daily lives of millions of inhabitants. Yet, the crop’s productivity and profitability are hampered by biotic stresses, including Exserohilum turcicum, causing leaf blight. A total of 101 sorghum accessions collected from Niger and Senegal, SC748-5 and BTx623, were evaluated in three different environments (Kaymor, Kolda, and Ndiaganiao) in Senegal for their reactions against the leaf blight pathogen. The results showed that 11 out of the 101 accessions evaluated exhibited 100% incidence, and the overall mean incidence was 88.4%. Accession N15 had the lowest incidence of 50%. The overall mean severity was 31.6%, while accessions N15, N43, N38, N46, N30, N28, and N23 from Niger recorded the lowest severity levels, ranging from 15.5% to 25.5%. Accession N15 exhibited both low leaf blight incidence and severity, indicating that it may possess genes for resistance to E. turcicum. Also, the accessions evaluated in this study were sequenced. A GWAS identified six novel single-nucleotide polymorphisms (SNPs) associated with an average leaf blight incidence rate. The candidate genes were found in chromosomes 2, 3, 5, 8, and 9. Except for SNP locus S05_48064154, all five SNPs associated with the leaf blight incidence rate were associated with the plant defense and stress responses. In conclusion, the candidate genes identified could offer additional options for enhancing plant resistance against E. turcicum through plant breeding or gene editing.

DeepRice: A deep learning and deep feature based classification of Rice leaf disease subtypes

Rice stands as a crucial staple food globally, with its enduring sustainability hinging on the prompt detection of rice leaf diseases. Hence, efficiently detecting diseases when they have already occurred holds paramount importance for solving the cost of manual visual identification and chemical testing. In the recent past, the identification of leaf pathologies in crops predominantly relies on manual methods using specialized equipment, which proves to be time-consuming and inefficient. This study offers a remedy by harnessing Deep Learning (DL) and transfer learning techniques to accurately identify and classify rice leaf diseases. A comprehensive dataset comprising 5932 self-generated images of rice leaves was assembled along with the benchmark datasets, categorized into 9 classes irrespective of the extent of disease spread across the leaves. These classes encompass diverse states including healthy leaves, mild and severe blight, mild and severe tungro, mild and severe blast, as well as mild and severe brown spot. Following meticulous manual labelling and dataset segmentation, which was validated by horticulture experts, data augmentation strategies were implemented to amplify the number of images. The datasets were subjected to evaluation using the proposed tailored Convolutional Neural Networks models. Their performance are scrutinized in conjunction with alternative transfer learning approaches like VGG16, Xception, ResNet50, DenseNet121, Inception ResnetV2, and Inception V3. The effectiveness of the proposed custom VGG16 model was gauged by its capacity to generalize to unseen images, yielding an exceptional accuracy of 99.94%, surpassing the benchmarks set by existing state-of-the-art models. Further, the layer wise feature extraction is also visualized as the interpretable AI.