scholarly journals A Lightweight Powdery Mildew Disease Evaluation Model for Its In-Field Detection with Portable Instrumentation

Agronomy ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 97
Author(s):  
Liang Gong ◽  
Chenrui Yu ◽  
Ke Lin ◽  
Chengliang Liu
Keyword(s):  
Powdery Mildew ◽  
Evaluation Model ◽  
A Priori ◽  
Gaussian Mixture ◽  
Infected Leaf ◽  
Plant Leaves ◽  
Spot Area ◽  
Computational Performance ◽  
Field Environment ◽  
Crop Disease

Powdery mildew is a common crop disease and is one of the main diseases of cucumber in the middle and late stages of growth. Powdery mildew causes the plant leaves to lose their photosynthetic function and reduces crop yield. The segmentation of powdery mildew spot areas on plant leaves is the key to disease detection and severity evaluation. Considering the convenience for identification of powdery mildew in the field environment or for quantitative analysis in the lab, establishing a lightweight model for portable equipment is essential. In this study, the plant-leaf disease-area segmentation model was deliberately designed to make it meet the need for portability, such as deployment in a smartphone or a tablet with a constrained computational performance and memory size. First, we proposed a super-pixel clustering segmentation operation to preprocess the images to reduce the pixel-level computation. Second, in order to enhance the segmentation efficiency by leveraging the a priori knowledge, a Gaussian Mixture Model (GMM) was established to model different kinds of super-pixels in the images, namely the healthy leaf super pixel, the infected leaf super pixel, and the cluttered background. Subsequently, an Expectation–Maximization (EM) algorithm was adopted to optimize the computational efficiency. Third, in order to eliminate the effect of under-segmentation caused by the aforementioned clustering method, pixel-level expansion was used to describe and embody the nature of leaf mildew distribution and therefore improve the segmentation accuracy. Finally, a lightweight powdery-mildew-spot-area-segmentation software was integrated to realize a pixel-level segmentation of powdery mildew spot, and we developed a mobile powdery-mildew-spot-segmentation software that can run in Android devices, providing practitioners with a convenient way to analyze leaf diseases. Experiments show that the model proposed in this paper can easily run on mobile devices, as it occupies only 200 M memory when running. The model takes less than 3 s to run on a smartphone with a Cortex-A9 1.2G processor. Compared to the traditional applications, the proposed method achieves a trade-off among the powdery-mildew-area accuracy estimation, limited instrument resource occupation, and the computational latency, which meets the demand of portable automated phenotyping.

scholarly journals Disease Resistance Genetics and Genomics in Octoploid Strawberry

2019 ◽  
Vol 9 (10) ◽  
pp. 3315-3332 ◽  
Author(s):  
Christopher R. Barbey ◽  
Seonghee Lee ◽  
Sujeet Verma ◽  
Kevin A. Bird ◽  
Alan E. Yocca ◽  
...  
Keyword(s):  
Disease Resistance ◽  
A Priori ◽  
Eqtl Analysis ◽  
R Gene ◽  
R Genes ◽  
Specialty Crop ◽  
Crop Disease ◽  
Strawberry Cultivar ◽  
Gene Collection ◽  
Resistance Genetics

Octoploid strawberry (Fragaria ×ananassa) is a valuable specialty crop, but profitable production and availability are threatened by many pathogens. Efforts to identify and introgress useful disease resistance genes (R-genes) in breeding programs are complicated by strawberry’s complex octoploid genome. Recently-developed resources in strawberry, including a complete octoploid reference genome and high-resolution octoploid genotyping, enable new analyses in strawberry disease resistance genetics. This study characterizes the complete R-gene collection in the genomes of commercial octoploid strawberry and two diploid ancestral relatives, and introduces several new technological and data resources for strawberry disease resistance research. These include octoploid R-gene transcription profiling, dN/dS analysis, expression quantitative trait loci (eQTL) analysis and RenSeq analysis in cultivars. Octoploid fruit eQTL were identified for 76 putative R-genes. R-genes from the ancestral diploids Fragaria vesca and Fragaria iinumae were compared, revealing differential inheritance and retention of various octoploid R-gene subtypes. The mode and magnitude of natural selection of individual F. ×ananassa R-genes was also determined via dN/dS analysis. R-gene sequencing using enriched libraries (RenSeq) has been used recently for R-gene discovery in many crops, however this technique somewhat relies upon a priori knowledge of desired sequences. An octoploid strawberry capture-probe panel, derived from the results of this study, is validated in a RenSeq experiment and is presented for community use. These results give unprecedented insight into crop disease resistance genetics, and represent an advance toward exploiting variation for strawberry cultivar improvement.

scholarly journals First report of Podosphaera macularis causing hop (Humulus lupulus) powdery mildew in Brazil

Plant Disease ◽  
2021 ◽  
Author(s):  
Mariana Mendes Fagherazzi ◽  
Fernando Sartori Pereira ◽  
Francine Regianini Nerbass ◽  
Evandro Zacca Ferreira ◽  
Vinícius Bizolo Sommer ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Direct Sequencing ◽  
Humulus Lupulus ◽  
Control Plot ◽  
Infected Leaf ◽  
Academic Press ◽  
Conidial Suspension ◽  
First Report ◽  
Powdery Mildews ◽  
Podosphaera Macularis

The hop (Humulus lupulus L.) is a dioecious perennial climbing plant grown commercially worldwide. Wild hops are widely distributed throughout the Northern Hemisphere, Europe, Asia, and North America (Neve, 1991). In the Southern Hemisphere, some of the leading hop-producing countries include South Africa, Australia, and New Zealand. Brazil began hop production less than 5 years ago. In January 2019, amphigenous white powdery circular fungal colonies were observed on the leaves and stems of hop plants (cultivar Chinook) within a 900m2 hop garden in Lages municipality, Santa Catarina State, southern Brazil. The incidence of the disease was present on almost 100 per cent of “Chinook” cultivar plants and diseased foliage was collected to identify the pathogen and used to inoculate healthy plants. Hop powdery mildew lesions with hyaline and septate mycelium with chains of unicellular conidia (n =100) hyaline, barrel-shaped, mean of length/width ± standard deviation 25–27 × 13–18 µm ± 0.980, with fibrosin bodies, and conidiophores erect with cylindrical foot cells, were visible within 10 days. The causal agent was identified as Podosphaera macularis (Wallr.:Fr.) Lind (synonym S. humuli (DC.) Burrill) on the basis of conidial shape, size and host range (Royle 1978; Braun 1987; Mahaffee et al., 2009), complemented with the present molecular analysis. Chasmothecia have not been observed in the field to date. A conidial suspension of 200 ml at concentration of 1.4 x 105 was mixed with 5ul of Tween® 20 for the pathogenicity assay. Ten plants of 9-month-old of hop “Chinook” cultivar, were inoculated with 5 ml of the conidial suspension using a manual spray. The control plot was only sprayed with water. The inoculated plants were maintained at 22ºC ± 1ºC with a 12-hour photoperiod and 65% relative humidity. White mycelia were visible first on the adaxial leaf surfaces of the inoculated younger leaves after 10 days and the disease severity reached between 2 to 5%. No symptoms were observed at the control plot. P. macularis infected most aerial plant tissues of the inoculated plants and caused approximately 50% of cones losses. P. macularis conidia were collected from the infected leaf tissue with a sterile soft camel-hair brush and DNA was extracted using a Wizard Genomic DNA extraction kit. The primers ITS1/ITS4 (White et al., 1990) were used to amplified and sequenced a fragment of the ITS region. PCR products were subjected to Sanger Sequencing to confirm sample species. The resulting 522-bp sequence was deposited into GenBank (accession n°. MN630490). BLASTn showed a 99.81% sequence identity with the CT1 isolate of P. macularis from H. lupulus (MH687414). The presence and identification of P. macularis in hop production regions is a new challenge to growers in Brazil. Research related to the knowledge of the disease cycle, epidemiology, and control strategies for the integrated management should be conducted, as there are no registered fungicides for powdery mildew on hop in Brazil. To our knowledge, this is the first report of P. macularis in Brazil, as well as in South America. References Braun, U. (1987) A Monograph of the Erysiphales (Powdery Mildews). J. Cramer, Berlin, German Democratic Republic. p 113. Mahaffee, W. F., Pethybridge, S.J., Gent, D.H (2009) Compendium of hop diseases and pests. The American Phytopathological Society Press, Saint Paul, Minnesota. Neve R. A (1991). Hops. Chapman and Hall: London. Royle, D. J (1978). Powdery mildew of the hop. Pages 381-409 in: The Powdery Mildews. D. M. Spencer, ed. Academic Press, New York. White, T. J., Bruns, T., Lee, S., and Taylor, J. (1990). Amplification and direct sequencing of fungal ribosomal RNA genes for phylogenetics. pp. 315-322 in: PCR Protocols: A Guide to Methods and Applications. M. Innis, D. Gelfand, J. Sninsky, and T. White, eds. Academic Press, San Diego.

scholarly journals First Report of Powdery Mildew Caused by Golovinomyces ambrosiae on Verbena bonariensis in Korea

Plant Disease ◽  
2021 ◽  
Author(s):  
In-Young Choi ◽  
Ho-Jong Ju ◽  
Kui-Jae Lee ◽  
Hyeon-Dong Shin
Keyword(s):  
Powdery Mildew ◽  
Large Subunit ◽  
Morphological Characteristics ◽  
Morphological Characterization ◽  
Control Measures ◽  
Width Ratio ◽  
Infected Leaf ◽  
Voucher Specimen ◽  
First Report ◽  
Pcr Products

Verbena bonariensis L., named as purple-top vervain or Argentinian vervain, is native to tropical South America. It is cultivated worldwide as an ornamental plant. During summer and autumn of 2020, over 50% of the leaves of V. bonariensis were found infected with powdery mildew in a flower garden in Seoul (37°35'19"N 127°01'07"E), Korea. White, superficial mycelia developed initially on the leaves and subsequently covered surfaces of leaves and stems, are resulting in leaf discoloration, early defoliation, and shoots distortion. Heavily infected plants lost ornamental value. A representative voucher specimen was deposited in the Korea University herbarium (KUS-F32168). Morphological characterization and measurements of conidiophores and conidia were carried out using fresh samples. Microscopic observation showed that aAppressoria on the superficial hypha were nipple-shaped, but rarely found or nearly absent. Conidiophores (n = 30) were cylindrical, 110 to 220 × 10 to 12 µm, and produced 2 to 5 immature conidia in chains with a sinuate outline, followed by 2 to 3 short cells. Foot-cells of conidiophores were straight, cylindrical, and 46 to 90 μm long. Conidia (n = 30) were hyaline, ellipsoid to doliiform, 28 to 40 × 18 to 24 μm with a length/width ratio of 1.3 to 2.0, and contained small be like oil-like drops, but without distinct fibrosin bodies. Primary conidia were apically rounded and sub-truncate at the base. Germ tubes were produced at perihilar position of the conidia. Chasmothecia were not observed. These morphological characteristics were typical of the conidial stage of the genus Golovinomyces (Braun and Cook 2012, Qiu et al. 2020). To identify the fungus, rDNA was extracted from the voucher sample. PCR products were amplified using the primer pair ITS1F/PM6 for internal transcribed spacer (ITS), and PM3/TW14 for the large subunit (LSU) of the rDNA (Takamatsu and Kano 2001). The resulting sequences were registered to GenBank (MW599742 for ITS, and MW599743 for LSU). Using Blast’n search of GenBank, sequences showed 100% identity for ITS and LSU with G. ambrosiae (MT355557, KX987303, MH078047 for ITS, and AB769427, AB769426 for LSU), respectively. Thus, based on morphology and molecular analysis, the isolate on V. bonariensis in Korea was identified as G. ambrosiae (Schwein.) U. Braun & R.T.A. Cook. Pathogenicity tests were carried out by touching an infected leaf onto healthy leaves of disease-free pot-grown plants using a replication of five plants, with five non-inoculated plants used as controls. After 7 days, typical powdery mildew colonies started to appear on the inoculated leaves. The fungus on inoculated leaves was morphologically identical to that originally observed in the field. All non-inoculated control leaves remained symptomless. On different global Verbena species, tThere have been many reports of Golovinomyces powdery mildews including G. cichoracearum s.lat., G. longipes, G. monardae, G. orontii s.lat., and G. verbenae (Farr and Rossman 2021). In China, G. verbenae was recorded on V.erbena phlogiflora (Liu et al. 2006). Golovinomyces powdery mildew has not been reported on Verbena spp. in Korea. Powdery mildew has been reported on V. bonariensis in California, but identity of the causal agent had not been reported. To our knowledge, this is the first report on the identity of the powdery mildew caused by G. ambrosiae on V. bonariensis in Korea. Since heavily infected plants lost ornamental value, appropriate control measures should be developed.

scholarly journals First Report of Podosphaera xanthii Causing Powdery Mildew on Mungbean (Vigna radiata) in Taiwan

Plant Disease ◽  
2021 ◽  
Author(s):  
Zong-ming Sheu ◽  
Ming-hsueh Chiu ◽  
Lawrence Kenyon
Keyword(s):  
Powdery Mildew ◽  
Vigna Radiata ◽  
Morphological Characteristics ◽  
Resistance Breeding ◽  
Its Region ◽  
Infected Leaf ◽  
Pathogenicity Test ◽  
Causal Organism ◽  
First Report ◽  
Powdery Mildew Pathogen

Mungbean (Vigna radiata L.) is routinely grown in the experimental fields at the headquarters of the World Vegetable Center (23°6'30.88"N, 120°17'51.31"E) for breeding, research and germplasm multiplication. In a spring 2016 mungbean trial, about 50% of the plants were affected with powdery mildew. The white, powdery-like patches first appeared on the upper leaf surfaces, and soon developed to grey patches on both sides of the leaves. Purple to brown discoloration appeared on the underside of the infected leaf. Microscopy examination revealed that the causal organism was not Erysiphe polygoni, which had previously been documented as the powdery mildew pathogen on mungbean in Taiwan (Hartman et al. 1993). The fungus produced typical structures of the powdery mildew Euoidium, anamorph of the genus Podosphaera. The mycelium consisted of septate, flexuous hyphae with indistinct appressoria. The erect conidiophores arising from superficial hyphae varied from straight or slightly curved to curled. Three to ten conidia were borne in long chains with crenate edges. Foot-cells were straight, cylindrical and measured 30 to 52 µm long. Conidia were hyaline, ellipsoid-ovoid to barrel-shaped, with fibrosin bodies, and measured 27 to 33 (mean = 30.4) × 15 to 20 (mean = 16.6) µm. Germ tubes were clavate and occasionally forked, and were produced from the lateral sites of the conidia. No chasmothecia were found in the samples. The morphological characteristics were consistent with P. xanthii (Castagne) U. Braun & Shishkoff (Braun & Cook 2012). To confirm the identity, the internal transcribed spacer (ITS) region of rDNA and partialβ-tubulin gene (TUB2) for the isolate MG3 were amplified with the primers ITS4/ITS5 (White et al. 1990) and BtuF5/BtuR7a (Ellingham et al. 2019), respectively. BLASTn analysis revealed the ITS sequence (MN833717) was 100% identical to many records of P. xanthii whereas the TUB2 sequence (MW363957) was 100% identical to a record of P. fusca (syn. P. xanthii; KC333362) in NCBI GenBank. A pathogenicity test was conducted by dusting conidia from an infected leaf onto six healthy four-week-old mungbean plants (cv ‘Tainan No. 3’). Another three plants were not inoculated and were used as control. All the plants were maintained in a greenhouse at 25 to 28°C. All inoculated plants developed powdery mildew symptoms after 10 days, whereas the control plants remained symptomless. To our knowledge, this is the first report of P. xanthii causing disease on mungbean in Taiwan. P. xanthii also has been reported on mungbean in Thailand (Meeboon et al. 2016), while other records referring to E. polygoni infecting Vigna spp. are from Brazil and Fiji (Farr & Rossman 2020). Although both P. xanthii and E. polygoni have now been reported as causing powdery mildew on mungbean in Taiwan, which species predominates or is more important remains unclear. A comprehensive survey with accurate species identification is required to develop effective management of the disease, particularly for resistance breeding.

Joint Scheduling of Vessel Traffic and Pilots in Seaport Waters

2020 ◽  
Vol 54 (6) ◽  
pp. 1495-1515 ◽  
Author(s):  
Shuai Jia ◽  
Lingxiao Wu ◽  
Qiang Meng
Keyword(s):  
Lagrangian Relaxation ◽  
Traffic Management ◽  
Programming Model ◽  
A Priori ◽  
Relaxation Algorithm ◽  
Congestion Mitigation ◽  
Computational Performance ◽  
Time Space ◽  
Path Assignment ◽  
Lagrangian Relaxation Algorithm

In the busiest seaports, vessel traffic and vessel pilotage management play a crucial role in congestion mitigation. The management of vessel traffic and pilotage involves scheduling the vessels for sailing into and out of a seaport and scheduling the pilots for navigating the vessels in the port waters. In this paper, we study the integrated vessel traffic and pilot scheduling problem of a seaport. We manage the vessel traffic by optimizing the utilization of the navigation channels and the utilization of the anchorage areas in the terminal basin and incorporate the decision of pilot scheduling into the decision of vessel traffic management for congestion mitigation and vessel service enhancement. We formulate the problem on a time–space network with vessel- and pilot-dependent arc costs and develop an integer programming model that minimizes the sum of the berthing and departure tardiness cost of vessels, the cost of unsatisfied vessel service requests, and the pilot dispatching cost. For solving the model, we enumerate feasible vessel paths a priori and develop a Lagrangian relaxation algorithm that decomposes the problem into a vessel and pilot path assignment subproblems. Computational performance of the Lagrangian relaxation algorithm is tested on problem instances generated based on the physical layout and operational data of the Waigaoqiao Port in Shanghai.

scholarly journals Analysis of Different Statistical Models in Probabilistic Joint Estimation of Porosity and Litho-Fluid Facies from Acoustic Impedance Values

Geosciences ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 388 ◽  
Author(s):  
Mattia Aleardi
Keyword(s):  
Acoustic Impedance ◽  
Statistical Models ◽  
Reservoir Characterization ◽  
A Priori ◽  
Gaussian Model ◽  
Gaussian Mixture ◽  
Correct Choice ◽  
Joint Estimation ◽  
Coverage Ratio ◽  
Non Parametric

We discuss the influence of different statistical models in the prediction of porosity and litho-fluid facies from logged and inverted acoustic impedance (Ip) values. We compare the inversion and classification results that were obtained under three different statistical a-priori assumptions: an analytical Gaussian distribution, an analytical Gaussian-mixture model, and a non-parametric mixtu re distribution. The first model assumes Gaussian distributed porosity and Ip values, thus neglecting their facies-dependent behaviour related to different lithologic and saturation conditions. Differently, the other two statistical models relate each component of the mixture to a specific litho-fluid facies, so that the facies-dependency of porosity and Ip values is taken into account. Blind well tests are used to validate the final predictions, whereas the analysis of the maximum-a-posteriori (MAP) solutions, the coverage ratio, and the contingency analysis tools are used to quantitatively compare the inversion outcomes. This work points out that the correct choice of the statistical petrophysical model could be crucial in reservoir characterization studies. Indeed, for the investigated zone, it turns out that the simple Gaussian model constitutes an oversimplified assumption, while the two mixture models provide more accurate estimates, although the non-parametric one yields slightly superior predictions with respect to the Gaussian-mixture assumption.

scholarly journals Multisensor RFS Filters for Unknown and Changing Detection Probability

Electronics ◽  
2019 ◽  
Vol 8 (7) ◽  
pp. 741
Author(s):  
Zhang ◽  
Li ◽  
Sun
Keyword(s):  
Detection Probability ◽  
A Priori ◽  
Gaussian Mixture ◽  
Multitarget Tracking ◽  
Probability Hypothesis Density ◽  
Inverse Gamma ◽  
Motion State ◽  
Performance Deterioration ◽  
Cphd Filter ◽  
Monitoring Area

The detection probability is an important parameter in multisensor multitarget tracking. The existing multisensor multi-Bernoulli (MS-MeMBer) filter and multisensor cardinalized probability hypothesis density (MS-CPHD) filter require that detection probability is a priori. However, in reality, the value of the detection probability is constantly changing due to the influence of sensors, targets, and other environmental characteristics. Therefore, to alleviate the performance deterioration caused by the mismatch of the detection probability, this paper applies the inverse gamma Gaussian mixture (IGGM) distribution to both the MS-MeMBer filter and the MS-CPHD filter. Specifically, the feature used for detection is assumed to obey the inverse gamma distribution and is statistically independent of the target’s spatial position. The feature is then integrated into the target state to iteratively estimate the target detection probability as well as the motion state. The experimental results demonstrate that the proposed methods can achieve a better filtering performance in scenarios with unknown and changing detection probability. It is also shown that the distribution of the sensors has a vital influence on the filtering accuracy, and the filters perform better when sensors are dispersed in the monitoring area.

scholarly journals Real Estate Investment Choices and Decision Support Systems

2019 ◽  
Vol 11 (11) ◽  
pp. 3110 ◽  
Author(s):  
Vincenzo Del Giudice ◽  
Pierfrancesco De Paola ◽  
Torrieri Francesca ◽  
Peter J. Nijkamp ◽  
Aviad Shapira
Keyword(s):  
Decision Support ◽  
Real Estate ◽  
Driving Forces ◽  
Evaluation Model ◽  
Methodological Approach ◽  
A Priori ◽  
Real Estate Market ◽  
High Performing ◽  
Complex Evaluation ◽  
Real Estate Investments

The evaluation of real estate assets is currently one of the main focal points addressed by territorial marketing strategies, with the view of developing high-performing or competitive cities. Given the complexity of the driving forces that determine the behavior of actors in a real estate market, it is necessary to identify a priori the factors that determine the competitive capacity of a city, to attract investments. The decision support system allows taking into account the key factors that determine the “attractiveness” of real estate investments in competitive urban contexts. This study proposes an integrated complex evaluation model that is able to map out and encapsulate the multidimensional spectrum of factors that shape the attractiveness of alternative real estate options. The conceptual–methodological approach is illustrated by an application of the model to a real-world case study of investment choice in the residential sector of Naples.

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