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Background: In Oman tobacco (Nicotiana tabacum; family Solanaceae) is a minor crop, which is produced only for local consumption. In 2015, tobacco plants exhibiting severe downward leaf curling, leaf thickening, vein swelling, yellowing and stunting were identified in fields of tobacco in Suhar Al-Batina region, Oman. These symptoms are suggestive of begomovirus (genus Begomovirus, family Geminiviridae) infection. Methods: Circular DNA molecules were amplified from total DNA extracted from tobacco plants by rolling circle amplification (RCA). Viral genomes were cloned from RCA products by restriction digestion and betasatellites were cloned by PCR amplification from RCA product, using universal primers. The sequences of full-length clones were obtained by Sanger sequencing and primer walking. Constructs for the infectivity of virus and betasatellite were produced and introduced into plants by Agrobacterium-mediated inoculation. Results: The full-length sequences of 3 begomovirus and 3 betasatellite clones, isolated from 3 plants, were obtained. Analysis of the full-length sequences determined showed the virus to be a variant of Chilli leaf curl virus (ChiLCV) and the betasatellite to be a variant of Tomato leaf curl betasatellite (ToLCB). Both the virus and the betasatellite isolated from tobacco show the greatest levels of sequence identity to isolates of ChiLCV and ToLCB identified in other hosts in Oman. Additionally clones of ChiLCV and ToLCB were shown, by Agrobacterium-mediated inoculation, to be infectious to 3 Nicotiana species, including N. tabacum. In N. benthamiana the betasatellite was shown to change the upward leaf rolling symptoms to a severe downward leaf curl, as is typical for many monopartite begomoviruses with betasatellites. Conclusions: The leaf curl disease of tobacco in Oman was shown to be caused by ChiLCV and ToLCB. This is the first identification of ChiLCV with ToLCB infecting tobacco. The study shows that, despite the low diversity of begomoviruses and betasatellites in Oman, the extant viruses/betasatellites are able to fill the niches that present themselves. [ABSTRACT FROM AUTHOR]

Background: In the late 1920s, A. E. Watkins collected about 7000 landrace cultivars (LCs) of bread wheat (Triticum aestivum L.) from 32 different countries around the world. Among which 826 LCs remain viable and could be a valuable source of superior/favorable alleles to enhance disease resistance in wheat. In the present study, a core set of 121 LCs, which captures the majority of the genetic diversity of Watkins collection, was evaluated for identifying novel sources of resistance against tan spot, Stagonospora nodorum blotch (SNB), and Fusarium Head Blight (FHB). Results: A diverse response was observed in 121 LCs for all three diseases. The majority of LCs were moderately susceptible to susceptible to tan spot Ptr race 1 (84%) and FHB (96%) whereas a large number of LCs were resistant or moderately resistant against tan spot Ptr race 5 (95%) and SNB (54%). Thirteen LCs were identified in this study could be a valuable source for multiple resistance to tan spot Ptr races 1 and 5, and SNB, and another five LCs could be a potential source for FHB resistance. GWAS analysis was carried out using disease phenotyping score and 8807 SNPs data of 118 LCs, which identified 30 significant marker-trait associations (MTAs) with -log10 (p-value) > 3.0. Ten, five, and five genomic regions were found to be associated with resistance to tan spot Ptr race 1, race 5, and SNB, respectively in this study. In addition to Tsn1, several novel genomic regions Q.Ts1.sdsu-4BS and Q.Ts1.sdsu-5BS (tan spot Ptr race 1) and Q.Ts5.sdsu-1BL, Q.Ts5.sdsu-2DL, Q.Ts5.sdsu-3AL, and Q.Ts5.sdsu-6BL (tan spot Ptr race 5) were also identified. Our results indicate that these putative genomic regions contain several genes that play an important role in plant defense mechanisms. Conclusion: Our results suggest the existence of valuable resistant alleles against leaf spot diseases in Watkins LCs. The single-nucleotide polymorphism (SNP) markers linked to the quantitative trait loci (QTLs) for tan spot and SNB resistance along with LCs harboring multiple disease resistance could be useful for future wheat breeding. [ABSTRACT FROM AUTHOR]

The Corynespora leaf fall disease of rubber trees, caused by the necrotrophic fungus Corynespora cassiicola, is responsible for important yield losses in Asian and African plantations, whereas its impact is negligible in South America. The objective of this study was to identify potential antagonists of C. cassiicola among fungal endophytes (i.e., Pestalotiopsis, Colletotrichum, and Trichoderma spp.) isolated from wild and cultivated rubber trees distributed in the Peruvian Amazon. We first tested the endophytes in dual in vitro confrontation assays against a virulent C. cassiicola isolate (CCP) obtained from diseased rubber trees in the Philippines. All Trichoderma isolates overran the CCP colony, suggesting some antagonistic mechanism, while species from the other genera behaved as mutual antagonists. Trichoderma isolates were then tested through antibiosis assays for their capacity to produce growthinhibiting molecules. One isolate (LA279), recovered as an endophyte from a wild Hevea guianensis specimen and identified as Trichoderma koningiopsis, showed significant antibiosis capacity. We demonstrated that LA279 was also able to endophytically colonize the cultivated rubber tree species (H. brasiliensis). Under controlled laboratory conditions, rubber plants were inoculated with three Trichoderma strains, including LA279, in combination with the pathogenic CCP. Results showed that 1 week preinoculation with the endophytes differentially reduced CCP mycelial development and symptoms. In conclusion, this study suggests that T. koningiopsis isolate LA279—and derivate compounds-could be a promising candidate for the biological control of the important rubber tree pathogen C. cassiicola. [ABSTRACT FROM AUTHOR]

Species of Septoria are commonly associated with leaf spot diseases of a broad range of plant hosts worldwide. During our investigation of fungi associated with leaf spot diseases in northern and northwestern Iran, several Septoria isolates were recovered from symptomatic leaves on different herbaceous and woody plants in the Asteraceae, Betulaceae, and Salicaceae families. These isolates were studied by applying a polyphasic approach including morphological and cultural data and a multigene phylogeny using a combined data set of partial sequences of the 28S nuc rRNA gene (large subunit [28S]), internal transcribed spacer regions and intervening 5.8S nuc rRNA gene (ITS) of the nuc rDNA operon, actin (actA), translation elongation factor 1-α (tef1), calmodulin (cmdA), β-tubulin (tub2), and DNA-directed RNA polymerase II second largest subunit (rpb2). Four novel species are proposed, namely, Septoria eclipticola on Eclipta prostrata, Septoria firouraghina on Cirsium arvense, Septoria guilanensis on Populus deltoides, and Septoria taleshana on Alnus subcordata. All species are illustrated, and their morphology and phylogenetic relationships with other Septoria species are discussed. [ABSTRACT FROM AUTHOR]

India is a highly populated agricultural country which has land area of 60.3% for agriculture purpose. The production of rice plant is decreased up to 20–30% because of various diseases. The most frequent diseases occurred in paddy leaves are leaf blast, leaf blight, false smut, brown spot and leaf streak. This paper mainly considers a method to detect the leaf diseases automatically using image processing techniques. To determine these diseases, the proposed methodology involves image Acquisition, image pre-processing, segmentation and classification of paddy leaf disease. In this proposed system, the features are extracted using hybrid method of discrete wavelet transform, scale invariant feature transform and gray scale co-occurrence matrix approach. Finally, the extracted features are given to various classifiers such as K nearest neighborhood neural network, back propagation neural network, Naïve Bayesian and multiclass SVM to categorize disease and non-disease plants. Many classification techniques are examined to classify the leaf disease. In experimental result, the proposed work is implemented in MATLAB software and performance of this work is measured in terms of accuracy. It is observed that multi class SVM provides the better accuracy of 98.63% when compared to other classifiers. [ABSTRACT FROM AUTHOR]

Studies were undertaken under controlled conditions into the effects of different foliage components (cotyledon, first, second and third leaf) at three plant ages (3, 5 and 7 weeks old) on development of Alternaria leaf spot disease, caused by Alternaria japonica or A. brassicae , in canola (Brassica napus cv. Thunder TT) and mustard (B. juncea cv. Dune). Alternaria japonica generally showed percentage disease index (%DI) values similar to A. brassicae across the two Brassica species, different foliage components and plant ages. %DI from either pathogen was greater in older plants than younger plants for the same foliage components in both cultivars. Field studies were then undertaken with canola to compare disease development from A. japonica and A. brassicae across different plant components (leaf, pod and stem) and the consequent adverse impact on seed yield. Alternaria japonica was more severe in terms of leaf area diseased (%LAD 62.6) and stem area diseased (%SAD 69.8) than pod area diseased (%PAD 25.5), whereas A. brassicae was more severe on leaves (%LAD 61.9) than on pods (%PAD 47.4) or stems (%SAD 41.0). Stem disease incidence was greater for A. japonica (%SDI 94.0) than for A. brassicae (%SDI 56.5), but pod disease incidence was greater for A. brassicae (%PDI 93.5) than for A. japonica (%PDI 86.1). For A. japonica , AUDPC values of leaf disease incidence (LDI, 283.5), leaf area diseased (LAD, 253.3) and leaf collapse (LCI, 149.5) resulted in a yield loss of 58.1%, similar to A. brassicae , where AUDPC values of LDI (277.8), LAD (247.2) and LCI (111.0) caused a yield loss of 59.4%. These findings explain observed acceleration of Alternaria leaf spot severity from A. japonica , as from A. brassicae , through the growing season as plants become more susceptible with increasing age, and as more susceptible, later developing leaves become abundant. For the first time, we demonstrate that under conducive field conditions for disease development, A. japonica can cause serious seed-yield losses of a magnitude similar to those occurring with A. brassicae. Alternaria brassicae is a widely recognised as a significant pathogen of oilseed brassicas, especially canola and mustard, infesting all plant components and causing adverse yield loss, whereas A. japonica is newly recognised but little understood. Disease epidemic development and yield impacts of the two species were compared, and the findings explained why Alternaria leaf spot epidemics accelerate during the growing season as foliage becomes more susceptible with age and as more susceptible, later developing leaves become abundant. This provides critical information for A. japonica in relation to timing of symptom appearance, susceptibility of different foliage components, disease progression, and associated severe yield loss. [ABSTRACT FROM AUTHOR]

[Objective] The study aimed to elucidate the physiological mechanism of dilferent resistance to kivvilruit canker, and identify the related indicators of resistance to kiwifruit canker. [Method] In this is study, six main kiwifruit varieties from Sichuan Province were used as materials, the resistance to canker by the inoculation of potted seedling and in vitro inoculation of shoots. The physiological mechanism of resistance difference was also analyzed from the morphological structure of branches and leaves, physiological and biochemical indexes. [Result] (i) There was significant difference in the morphological structure of branches and leaves of 6 kiwifruit varieties. The stomatal density and stomatal lenglli of leaves were significantly or positively correlated with disease index in vitro inoculation lest of canker disease (the correlation coefficients were 0. 9636 and 0. 8858, respectively). The thickness of leaf sponge tissue was negatively correlated with die disease index of ulcer disease in vitro inoculation test (die correlation coefficient was —0. 9442). There was no significant correlation between die thickness of upper epidermis, lower epidermis, palisade tissue, stomatal width, length , width, density and thickness of bud-eye cortex of leaves and disease index of canker inoculation in vitro, and there was no obvious regularity in the shape of the skin hole. (ii) The activities of SOI), POD, CAT, PPO and PAL in shoots and leaves increased in varying degrees alter inoculation with pathogenic bacteria. The activities of SOD and POD in healthy leaves and shoot phloem were significant extremely or significant negative correlation with the canker disease index (correlation coefficients were -0. 9563, -0.9680, -0. 9517 and —0. 8088 respectively). There were no significant correlations between the activities of CAT, PPO and PAL in leaves and of CAT and PAL in shoot phloem and the canker disease index. The PPO activity in shoot phloem was significantly negatively correlated with canker index (correlation coefficient was -0. 9850). The soluble sugar content in the leaves and shoot phloem was significantly negatively correlated with the canker index before the inoculation of canker bacteria (correlation coefficients were —0.9220 and —0.8452 respectively) , However, there was no significant correlation between soluble starch in phloem of leaves and branches and disease index of canker. [Conclusion] The resistance of six Kiwifruit cultivars to canker disease from strong to weak was Cuivu, Donghong, Eton 1 , Jinguo, Jinyan and Hongyang. The stomatal density, stomatal length, thickness of spongy tissue, SOD activity, POD activity and soluble sugar content in phloem of leaves and branches are powerful indexes for evaluating the anti-ulcer ability of kiwifruit. [ABSTRACT FROM AUTHOR]

Mycosphaerella leaf disease (MLD) is a pathogen of eucalypt plantations causing leaf spots and defoliation, and affecting growth. In this study, two different dosages of nitrogen fertilisation together with a control treatment currently used for two clones being affected by MLD (C18 and C25) of Eucalyptus dunnii were tested. We measured root collar diameter (D) and height (H), and assessed disease severity in the apical, middle and basal portions of the crown at planting, three months after planting and five months after planting, and determined the Area Under Disease Curve Progress at the end of the study, for the following fertilisation treatments: reduced dosage 22.0 kg ha−1 of NH4NO3; control dosage 44.0 kg ha−1 of NH4NO3; and increased dosage 66.0 kg ha−1 of NH4NO3. We added 133.4 kg ha−1 of P2O5 and 28.0 kg ha−1 of KCl to each treatment. MLD severity was higher in the basal portion of the crown. Only for C18 did the control dosage and the increased dosage promote growth in root collar diameter and reduce MLD severity, respectively. For C25 there were no differences for the variables across the fertilisation treatments. For C18 correlation analysis indicated that increased nitrogen dosage reduced MLD severity (r = 0.83; p < 0.01). In conclusion, improved nitrogen fertilisation proved to be effective to reduce severity, but differences were observed between clones and fertilisation. [ABSTRACT FROM AUTHOR]

A systematic field study was conducted in agricultural fields such as food crops, pulses, vegetable crops, oil crops and commercial crops to estimate infestation of Echinochloa crus – galli (barnyard grass), a common terrestrial weed belonging to family poaceae. The in vitro pathogenicity studies on barnyard grass were conducted using spore inoculum (8X107/ml) of an indigenous fungus, Colletotrichum gloeosporioides. The pathogen was re-isolated from inoculated plants to fulfill Koch’s postulates and confirmed its host specificity on barnyard grass. The disease by the isolate was critically analyzed and the results revealed that Colletotrichum gloeosporioides is a potential agent to biological control of barnyard grass. The results revealed that the pathogen causes significantly (P < 0.05) severe infection on host weed and destructs the weed population by leaf spot diseases. The findings of the research suggested that the isolate Colletotrichum gloeosporioides is highly virulent and host-specific, and recommended for further studies as a promising biocontrol agent against barnyard grass weed. [ABSTRACT FROM AUTHOR]

In a survey of experimental and commercial fields in different locations of southwest Nigeria, severe mosaic, vein banding and yellowing were observed on bitter leaf plants (Vernonia amygdalina). RT-PCR carried out using total RNA isolated from infected leaf samples and a pair of potyvirus-specific primers yielded an amplicon (~700 bp) from all symptomatic samples, indicating the presence of a potyvirus infection. The amplicon was cloned and sequenced. Basic local alignment search tool analysis reveals that while the coat protein (CP) gene was more closely related (77%) to that of narcissus yellow stripe virus (NYSV), the amino acid sequence of the present virus isolate was more closely related (80%) to that of Colombian datura virus (CDV). The phylogenetic analysis of the virus sequences with selected potyvirus sequences revealed the closest relationship with jasmine ringspot virus. Based on sequence identity at the nucleic acid and protein levels as well as on phylogenetic analysis, the isolate in this study was considered not to be an isolate of jasmine ringspot virus. This mosaic disease of Vernonia in Nigeria was induced by a new, hitherto uncharacterized potyvirus, tentatively named Vernonia mosaic virus (VeMV). [ABSTRACT FROM AUTHOR]

Siela variety is a new high-performance barley feed. It is created at the the Institute of Agriculture - Karnobat by the method of combination selection. The biological and economic qualities of the variety have been tested in the Institute's Variety Tests for several years, and in the Executive Agency of Variety Testing, Field Inspection and Seed Control trials during the years 2016-2017 and 2017-2018 years. At the points of the ecological network it shows high productivity. The average yield obtained from 5 points of the country of the new variety is proven to be higher than the average standard (Veslets and Aheloy 2) by 13.6%. During the test period, the variety yields up to 810 kg/da. It has a high protein content of 11.82%, which makes it perfectly suited for feed purposes. The variety has high winter resistance and high resistance to logging. On a natural infectious background under field conditions, Siela exhibits an average to very good resistance to barley leaf diseases. Siela has been recognized as an original variety by order No. RD 12-1/ 8.03.2019 of the Minister of Agriculture, Food and Forestry and has been approved for entry in list A of the Official Variety List of the Republic of Bulgaria. The variety has high productive potential and is suitable for cultivation in all regions of the country. [ABSTRACT FROM AUTHOR]

This study provides a phylogeographic insight into the population diversity of Xanthomonas translucens strains causing bacterial leaf streak disease of small-grain cereals in Iran. Among the 65 bacterial strains isolated from wheat, barley, and gramineous weeds in eight Iranian provinces, multilocus sequence analysis and typing (MLSA and MLST) of four housekeeping genes (dnaK, fyuA, gyrB, and rpoD), identified 57 strains as X. translucens pv. undulosa, while eight strains were identified as X. translucens pv. translucens. Although the pathogenicity patterns on oat and ryegrass weed species varied among the strains, all X. translucens pv. undulosa strains were pathogenic on barley, Harding's grass, rye (except for XtKm35) and wheat, and all X. translucens pv. translucens strains were pathogenic on barley and Harding's grass, while none of the latter group was pathogenic on rye or wheat (except for XtKm18). MLST using the 65 strains isolated in Iran, as well as the sequences of the four genes from 112 strains of worldwide origin retrieved from the GenBank database, revealed higher genetic diversity (i.e., haplotype frequency, haplotype diversity, and percentage of polymorphic sites) among the Iranian population of X. translucens than among the North American strains of the pathogen. High genetic diversity of the BLS pathogen in Iran was in congruence with the fact that the Iranian Plateau is considered the center of origin of cultivated wheat. However, further studies using larger collections of strains are warranted to precisely elucidate the global population diversity and center of origin of the pathogen. [ABSTRACT FROM AUTHOR]

Soybean fungal diseases such as Blight, Frogeye leaf spot and Brown Spot are a significant threat to soybean plant due to the severe symptoms and lack of treatments. Traditional diagnosis of the thease diseases relies on disease symptom identification based on neaked eye observation by pathalogiest, which can lead to a high rate of false-recognition. This work presents a novel system, utilizing multiclass support vector machine and KNN classifiers, for detection and classification of soybean diseases using color images of diseased leaf samples. Images of healthy and diseased leaves affected by Blight, Frogeye leaf spot and Brown Spot were acquired by a digital camera. The acquired images are preprocessed using image enhancement techniques. The background of each image was removed by a thresholding method and the Region of Interest (ROI) is obtained. Color-based segmentation technique based on Incremental K-means clustering is applied to the region of interest for partitioning the diseased region. The severity of disease is estimated by quantifying a number of pixels in the diseased region and in total leaf region. Different color features of segmented diseased leaf region were extracted using RGB color space and texture features were extracted using Gray Level Co-occurrence Matrix (GLCM) to compose a feature database. Finally, the support vector machine (SVM) and K-Nearest Negbiour (KNN) classifiers are used for classifying the disease. This proposed classifers system is capable to classify the types of blight, brown spot, frogeye leaf spot diseases and Healthy samples with an accuracy of 87.3% and 83.6% are achieved. [ABSTRACT FROM AUTHOR]

Objective: To study the anti-respiratory syncytial viruses(RSV) mechanism of extracts from Hibiscus mutabilis leaf in vitro. Methods: Elibavirin was used as the positive drug to detect the anti-RSV activity of extracts from Hibiscus mutabilis leaf. By observing the antiviral effect of the extracts of Hibiscus mutabilis leaf in different ways of administration, the anti-RSV mechanism of the extracts of Hibiscus mutabilis leaf was preliminarily explored. Results: Hibiscus mutabilis leaf extracts could effectively inhibit the cytopathic changes caused by RSV, and had significant antiviral effect. The therapeutic index (TI) was 86.24. Conclusion:Hibiscus mutabilis leaf extracts have significant anti-RSV effect in vitro, and their antiviral effect occurs after virus penetration. [ABSTRACT FROM AUTHOR]

This study reveals the vulnerability of the Ecuadorian banana industry to diseases caused by leaf spotting of Sigatoka, which affects the productivity of banana plantations. The pathogen was described and information was collected from several scientific articles and studies in banana producer's countries, as a result of the theoretical review evidence of reduced production, increased doses and applications of fungicides. Generating a greater environmental impact as a result of the phytosanitary control mechanisms that in turn increase production costs becoming an unsustainable production system. [ABSTRACT FROM AUTHOR]

The rubber tree (Hevea brasiliensis) is the only resource for commercial natural rubber production and thus has economic importance in Southeast Asia. A spot disease on the leaves of a rubber tree was first discovered in 2017 in Hainan, China. In this study, the fungal isolate MA1 from the infected tissues was determined to be a pathogen of the spot disease by satisfying Koch's postulates. The isolate MA1 was identified as Bipolaris bicolor based on the morphological characteristics and multigene phylogenetic analysis. Among fungicides, prochloraz, iprodione and pyraclostrobin significantly inhibited hyphal growth of B. bicolor under in vitro conditions. This study constitutes the first report on the association of B. bicolor with leaf spot disease of rubber trees worldwide. [ABSTRACT FROM AUTHOR]

‘Haedamssal’ is an early maturing and rice stripe virus disease-resistant cultivar adaptable for early-transplanting cultivation that was developed by the rice breeding team of the Department of Southern Crop, NICS, RDA, in 2014. This cultivar was derived from the cross YR25869 (YR21247-B-B-B-49-1/Sasanishiki BL4//Koshihikari) and YR25868 (Unkwang//YR21247-B-B-B-49-1/Sasanishiki BL4) made in the 2005/2006 winter season and was advanced to the F5 generation by a bulk breeding method using rapid generation advance. To incorporate rice stripe virus resistance, marker-assisted selection on the RSV gene was conducted in 3-way and 6-way cross F1 generation using the tightly linked marker RM6897. From testing in the replicated yield trial in 2011, a promising line YR26258-B-B-B-33-3 was selected and it was designated as ‘Milyang276’. A local adaptability test of ‘Milyang276’ was performed at three locations from 2012 to 2014 and it was named as ‘Haedamssal’, which was a good eating quality variety. The culm length was 67 cm in yield trials, which was 4 cm shorter than ‘Jopyeong’. The number of spikelets per panicle was lower than ‘Jopyeong’, whereas the number of tillers per hill was higher. This variety was resistant to RSV disease, bacterial blight, and leaf blast disease. The milled rice yield of ‘Haedamssal’ was 5.48 MT per ha at the early transplanting in the local adaptability test. ‘Haedamssal’ is well adapted to early transplanting cultivation in the southern plain area (Registration No. 6811). [ABSTRACT FROM AUTHOR]

‘Yeongbo’ is a variety of japonica rice (Oryza sativa L.) with good eating quality, resistance to rice stripe virus, rice dwarf virus, and bacterial blight disease. It was developed by the rice breeding team of the Yeongdeok Branch, National Institute Crop Science, Rural Development Administration in 2014. This variety was derived from a cross between ‘Yeongdeog35’ with good eating quality and ‘Saekyehwa’ with good plant type in the 2002 summer season. A promising line selected through the pedigree breeding method, YR24269-1-2-1-2-3-3, was designated as ‘Yeongdeog57’ in 2011. After a local adaptability test at nine locations from 2012 to 2014, ‘Yeongdeog57’ was released under the name of ‘Yeongbo’ in 2014. ‘Yeongbo’ had a short culm length of 66 cm and medium growth duration. This variety was resistant to K1, K2, and K3 races of bacterial blight, rice stripe virus, and dwarf virus, and moderately resistant to leaf blast disease. ‘Yeongbo’ had translucent and clear milled rice kernel without white core and belly, and good eating quality according to a panel test. The yield potential of ‘Yeongbo’ in milled rice was approximately 5.75 MT/ha at an ordinary fertilizer level in the local adaptability test. This cultivar would be adaptable to middle plain area, south plain area, Yeongnam plain area, east costal area, and south mid-mountainous area. (Registration No.6804) [ABSTRACT FROM AUTHOR]

Nine isolates of Pyrenophora graminea, barley leaf stripe disease causal agent, collected from several regions in Algeria were evaluated under greenhouse conditions for their virulence to a collection of barley cultivars including three most cultivated Algerian varieties. Virulence levels were observed among the set of isolates and a mean disease rate ranging from 3.33% to 75.83% was found. Pathogenic variability of P. graminea and resistant gene effects in barley cultivars were revealed. Isolate OS was the most virulent among P. graminea isolates making it a suitable virulent isolate in future breeding programs. A set of 8 barley genotypes composed of common Algerian cultivars and local developed lines were tested for their reaction to P. graminea and yield response. Barley cultivar Minnesota 23 and line 18/17/7L2 were the most resistant of the collection with high grain number/ear and thousand grains weight even when diseased. These genotypes could be useful to integrate as candidate genitor plants into barley breeding programs to develop resistant cultivars to leaf stripe disease. [ABSTRACT FROM AUTHOR]

Leaf scald, caused by the necrotrophic fungus Monographella albescens, is one of the main threats to rice (Oryza sativa L.) around the world. This disease decreases yields in rice by up to 30% because of dead leaf tissue, damaged seeds, and sterile flowers. Currently, there is limited knowledge about the molecular mechanisms involved in rice plant resistance against this pathogen. For this purpose, six commercial cultivars of rice were primarily screened for M. albescens infection and development. Dasht and Salari were found to be the most resistant and susceptible to M. albescens infection, respectively. The plants were kept in a greenhouse at 29 ± 2°C during the day and 26 ± 2°C at night with a relative air humidity of 85 ± 5%. Forty-five days after sowing, the plants with three biological replications were inoculated by transferring a PDA disc (0.3 cm2) containing M. albescens mycelia to the middle third of the 7th, 8th, and 9th completely open leaves. The leaves were collected 24, 48, 72, 96 and 120 hai. Leaf samples were also collected from the non-inoculated plants (0 h) to serve as controls. Real-time quantitative PCR (RT-qPCR) showed rapid induction and significant accumulation of jasmonic acid (JA) and ethylene (ET) responsive genes such as lipoxygenase (LOX), allene oxide synthase 2 (Aos2), jasmonic acid carboxyl methyltransferase 1 (JMT1) and ACC synthase 1 (ACS1) in the resistant Dasht cultivar after infection with M. albescens. Furthermore, the transcripts of salicylic acid (SA) responsive phenyl alanine ammonia lyase 1 (PAL1) and nonexpressor of pathogenesis-related genes 1 (NPR1) genes were induced in the incompatible interaction. The activities of the defense enzymes superoxide dismutase (SOD), peroxidase (POX) and glutathione reductase (GR) increased strongly in Dasht in response to M. albescens infection. In addition, there was an increase in the H2O2 levels in the leaves of the Dasht cultivar during the infectious period of M. albescens associated with the enhancement of catalase (CAT) activity as well as higher levels of malondialdehyde (MDA). This is the first study on the interaction between rice and M. albescens at the molecular level. It can contribute to understanding how rice responds to pathogen infection, as well as assist with future research plans of molecular breeding regarding the tolerance to leaf scald disease. [ABSTRACT FROM AUTHOR]

Greengram is rightly called the poor man's meat. It has high digestibility due to which it is fed to babies, convalescents and elders. Leaf crinkle is one among the viral diseases that infects this crop and reduces yield quantity and quality of the seed. The symptoms of disease appear in the form of extreme crinkling, curling, puckering and rugosity of leaves, stunting of plants, malformation of floral organs and pollen fertility and pod formation is also reduced severely in infected plants. An intensive roving survey was conducted in major greengram growing regions of northern Karnataka viz., Belagavi, Bidar, Dharwad, Gadag, Haveri, Kalaburgi, Koppal, Raichur, Uttar Kannada and Yadagir showed that the highest mean per cent disease incidence recorded was 45.20 per cent in Yadagir district while lowest recorded in Haveri (17.17%) district during 2011-12, while during 2012-13 survey also Yadagir district recorded the high of 42.50 per cent mean PDI and Haveri (16.89%) was recorded lowest mean PDI. All surveyed districts in northern Karnataka are coming under different agro climatic zones hence variation in PDI is may be due to variations in maximum and minimum temperature, relative humidity, rainfall, health of seed material, vector population and vector movement. [ABSTRACT FROM AUTHOR]

Blackgram is popular as "Urad dal" in India and it is highly prized pulse among all the pulses. Blackgram has medical properties which help to heal Rheumatic pains, stiff shoulder and contracted knees. Leaf crinkle is one among the viral diseases that infects these crops and reduces yield quantity and quality of the seed. The symptoms of disease appear in the form of extreme crinkling, curling, puckering and rugosity of leaves, stunting of plants, malformation of floral organs and pollen fertility and reduced pod formation in severely infected plants. An intensive roving survey was conducted in seven district of northern Karnataka viz., Belagavi, Bidar, Dharwad, Haveri, Raichur, Uttar Kannada and Yadagir to know the incidence of leaf crinkle disease in blackgram during kharif 2011 and 2012. During kharif 2011 roving survey the highest mean PDI of 39.13 recorded in Bidar district while lowest was recorded in Haveri district (21.20%). In kharif 2012 also Bidar recorded highest mean PDI (42.87%) and the lowest of 19.60 per cent in Haveri. The area covered under survey in northern Karnataka belongs to different agro climatic zones hence leaf crinkle disease is varied. [ABSTRACT FROM AUTHOR]

Vine culture is influenced by many factors, such as the weather, soil or topography, which are triggers to phytosanitary issues. Among them are some diseases, that are responsible for major economic losses that can, however, be managed with timely interventions in the field, viable of leading to effective results by preventing damage propagation. While not all symptoms might present a visible evidence, hyperspectral sensors can tackle this aspect with their ability for measuring hundreds of continuously sparse bands that range beyond the eye-perceptible spectrum. Having such research line in mind in this work, a hyperspectral sensor was applied to analyse the spectral status of vine leaves samples, collected in three chronologically distinct campaigns, while costly and destructive laboratory methods were used to track Flavescence Dorée (FD) in the same samples, for a ground truth information. Regarding data processing, machine learning approaches were used, in which several classifiers were selected to detect FD in vine leaves hyperspectral images. The goal was to evaluate and find most suitable classifier for this task. [ABSTRACT FROM AUTHOR]

A survey was conducted to identify fungi associated with leaf diseases of ornamental herbs, including Christ plant, dracaena, rose geranium, rose periwinkle and treasure flower, in Ahvaz, southwestern Iran. Twenty‐five symptomatic herbs were collected and studied, which led to the isolation of seven Phoma‐like strains belonging to four taxa. These fungi were characterised based on DNA sequence data for the partial large subunit 28S nrDNA (LSU‐D1/D2), the internal transcribed spacer 1 and 2 and 5.8S nrDNA (ITS) and part of the β‐tubulin (tub2) gene regions. A multi‐locus‐based phylogeny, in combination with morphology, allowed for the identification of Allophoma hayatii, A. labilis, A. tropica and a novel species of the genus Ectophoma. Ectophoma iranica sp. nov. is morphologically and genetically distinctive from previously described species. In pathogenicity tests, the two strains of E. iranica (CBS 144681 and IRAN 3354C) caused leaf spot symptoms on leaves of Catharanthus roseus. New host plant species and records for A. hayatii, A. labilis and A. tropica are reported, plus further emended characterization of A. hayatii. [ABSTRACT FROM AUTHOR]

The viruses Sugarcane mosaic virus (SCMV) and Sugarcane streak mosaic virus (SCSMV) causing mosaic disease and Sugarcane yellow leaf virus (SCYLV) causing yellow leaf disease (YLD) are synergistically associated with varietal degeneration of sugarcane in India. The objectives of the study were to understand the degree of degeneration in the sugarcane cultivar CoJ 64 due to the mixed infection of the three viruses. The study was also aimed to quantify the threshold limit of viruses for the plant to express the symptoms. Symptomatic plants exhibited significant reductions in germination and growth as compared to the asymptomatic plants and maintained poor vigour. Such plants recorded significant reductions in different physiological parameters such as photosynthetic rate, stomatal conductance, transpiration rate, chlorophyll fluorescence ratio and leaf chlorophyll content. At the time of harvest a drastic reduction in the juice yield by 30.13–36.04% was found. Diagnosis by qRT-PCR revealed that both asymptomatic and the symptomatic plants showed mixed infections of all the three viruses. The copy numbers in the asymptomatic plants were detected between 102 and 103 for all the three viruses whereas, the copy numbers in the symptomatic plants were in the range of 104 and 106 for all the three viruses. The present study established a threshold limit of three RNA viruses causing varietal degeneration in sugarcane and this information will be used while selecting new varieties to avoid varietal degeneration under field conditions. [ABSTRACT FROM AUTHOR]

Niger (Guizotia abyssinica Cass.) is an important minor oil seed crop grown in dry areas grown mostly by tribal and interior places as life line of tribal segment. Tribal people mainly use its oil for cooking purpose, above than that there were also other uses. Hence, the niger crop should be protected from the infection. The crop is affected by number of fungal diseases. Therefore, a field experiment was formulated for three years with the four replications at the Niger Research Station (NRS) at Navsari Agricultural University (NAU), Vanarasi, Navsari (Gujarat) on the foliar diseases of GN-1 variety of niger crop. In this experiment, six different fungicides along with one control have been evaluated to control the Alternaria and Cercospora leaf spot diseases, out of which all the fungicidal treatments were significantly superior over the control. Here, foliar spray on the incidence of diseases was compared with the control (without any treatment). All the fungicidal treatments were significantly superior over the control to reduce Alternaria and Cercospora leaf spot diseases of Niger crop. Treatment of Carbendazim + Mancozeb (0.2 %) with two sprays first from the initiation of the disease and second after the interval of 15 days recorded the lowest incidence of Alternaria (14.56) and Cercospora (14.94) leaf spot diseases of niger and recorded the highest seed yield 337 seed yield kg/ha along with the net return with cost benefit ratio graph. [ABSTRACT FROM AUTHOR]

This research aimed to study the compatibility of antagonistic bacteria that effective to control rice bacterial leaf blight disease, including Bacillus pumilus FDKF5 and Bacillus sp. IKM1 with agricultural chemicals and bio-products. Compatibility test of antagonistic bacteria with pesticides by using poison plate method showed that B. pumilus FDKF5 and Bacillus sp. IKM1 were able grow together with eight pesticides including 5 types of insecticide such as Conbalis (pyridaben 20% WP), Centaur (imidachloprid 70% WG), Posch (carbosulfan 20% W/V EC), Microthiol sulfur (sulfur 80% WG) and Abamectin (abamectin 1.8% W/V EC) and 3 types of fungicide including Terraclor Super-X (etridiazole 6% + quintozene 4% W/V EC), Fundasol 50 (benomyl 50% WP) and Octave (prochloraz 50% WP). However, streptomycin sulfate bactericide was inhibited their growth. Co-culture test of antagonistic bacteria with bio-products by using dual culture technique showed that Trichoderma and Beauveria bio-products could overgrowth on colonies of antagonistic bacteria but did not inhibit their growth. While, Metarhizium bio-products could inhibit the growth of both antagonistic bacteria. Dual culture of antagonistic bacteria with Bacillus bio-product showed that Bacillus sp. IKM1 could grow very well while B. pumilus FDKF5 could grow moderately. [ABSTRACT FROM AUTHOR]

Corynespora leaf fall disease (CLF), caused by the fungus Corynespora cassiicola (Berk. & Curt.) Wei, has occurred and become a serious disease on rubber (Hevea brasiliensis) in Asian countries, including Vietnam. Field experiments were conducted in order to evaluate the efficacy of four chemical fungicides difenoconazole, difenoconazole+propiconazole, epoxiconazole and tebuconazole for controlling CLF in Thua Thien Hue province, Central Vietnam. These insecticides were applied at recommended field rates. The results showed that all the four tested fungicides were moderate or high efficacy against CLF. The efficacy was highest with difenoconazole (64.4-71.5%) on rubber planted at both the two different ecological zones. These results suggest that difenoconazole application provides one potential component of an effective CLF control strategy for rubber farmers. [ABSTRACT FROM AUTHOR]

Leaf spot and rough bark diseases are of high concern among cinnamon growers in Sri Lanka due to potential yield losses. Comprehensive information on distribution and intensity of the above diseases is not available in Sri Lanka. During this study, disease assessment keys were developed for leaf spot and rough bark diseases with subjective scales, which could be useful in assessing the severity of the two diseases. Two hundred and eighty cinnamon accessions from major cinnamon growing areas of Matara, Galle, Kalutara, Kurunegala, Ratnapura and Humbantota Districts were used to determine the intensities of the above diseases. All the districts showed a high level of leaf spot disease severity, where 23.81% accessions from Galle and 17.14% accessions from Kalutara districts exhibited the leaf spot disease severity scale of 6. Moreover, 60% accessions from Kurunegala and 45.71% accessions from Kalutara districts showed the leaf spot disease severity scale of 5. According to the study on rough bark disease severity, none of the major cinnamon growing areas is at a high risk of rough bark disease. However, the present study indicates the initiation and progression of rough bark disease in the six districts, where Matara district showed considerable levels of infection having 17.39%, 11.59%, 5.80% and 4.35% of accessions with disease severity scales 2, 3, 4 and 5, respectively. The estimates of the two disease severities explain the present scenario of extent of the two diseases across major cinnamon growing areas in the country. [ABSTRACT FROM AUTHOR]

BACKGROUND: Tenuazonic acid (TeA), a putative nonhost‐selective mycotoxin isolated from Alternaria alternata, is the main causative agent of brown leaf spot disease of crofton weed (Ageratina adenophora) and some other crops. Previous studies revealed that it is a natural photosystem II inhibitor that binds the D1 protein to block electron transfer. Though the crude metabolite extract of A. alternata containing TeA has been bioassayed, the herbicidal activity of synthesized TeA has not been systematically evaluated yet. RESULTS: TeA caused leaves of crofton weed to have brown spots that were more pronounced in older leaves than younger ones. It completely killed 92% of the four‐leaf seedlings at 600 g ai/ha but only 81% or less of six‐leaf seedlings or bigger. The bioassay of phytotoxicity of TeA to 67 plant species including 54 weeds and 13 crops, showed that TeA had a broad weed spectrum but low toxicity to Solanaceae and Malvaceae species. Further potted‐ plant experiments demonstrated that TeA had EC90 values that ranged from 119 to 795 μg/mL for 14 important weeds but was 2539 μg/mL for Acalypha australis. Nicotiana tabacum and Gossypium hirsutum had no injury symptoms at 1000 μg/mL. A field trial showed that TeA effectively controlled two important weeds, Digitaria sanguinalis and Amaranthus retroflexus without affecting cotton in the field. CONCLUSION: TeA has potential as a biobased herbicide for controlling important dicotyledon and monocotyledon weeds in cotton and tobacco fields. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Black leaf streak disease, or black Sigatoka, is caused by the fungus Pseudocercospora fijiensis, and has been identified as a major constraint to global production of banana and plantain. We fitted a climatic niche model (CLIMEX) for P. fijiensis to gain an understanding of the patterns of climate suitability, and hence hazard from this disease. We then calibrated the climate suitability patterns against the results of an expert elicitation of disease pressure patterns. We found a moderately strong non-linear relationship between modelled climate suitability for P.°fijiensis and the expert ratings for disease pressure. The strength of the relationship provides a cross-validation between the CLIMEX model and the expert elicitation process. The bulk of global banana production experiences high potential threat from P. fijiensis, and the higher yielding areas for banana and plantain production are at greatest threat. By explicitly considering the role of irrigation we have been able to identify how strategic irrigation could be used to support banana production in areas that are at low risk from P. fijiensis. [ABSTRACT FROM AUTHOR]

Severe brown leaf spot disease was observed on Paris polyphylla var. chinensis in Sichuan Province, China, in 2017 and 2018. The initial symptoms were many light‐brown small spots with necrotic centres, round or irregular in shape, becoming dark brown, gradually enlarging and eventually coalescing, causing extensive leaf senescence. A fungus was isolated from diseased leaves showing typical symptoms of brown leaf spot. The isolates were cultured on potato sucrose agar, and their morphological characteristics of the causal pathogen were observed under a light microscope. Pathogenicity tests revealed that this fungus was the causal pathogen of the disease. Molecular analyses of the sequences of the ribosomal DNA internal transcribed spacer (ITS) region, translation elongation factor 1‐alpha (TEF) and the RNA polymerase II second largest subunit (RBP2) gene were conducted to confirm the identity of the pathogen. The multi‐gene phylogeny indicated that the causal agent was Alternaria tenuissima. To our knowledge, this is the first report of A. tenuissima causing brown leaf sports on P. polyphylla var. chinensis in China. [ABSTRACT FROM AUTHOR]

In July 2018, a yellow mottle leaf disease was observed on the leaves of Euonymus bungeanus Maxim plants in Liaoning Province of China. Typical flexuous filaments (diameter, 13 nm; length, ca. 500 nm) were observed in extracts on the symptomatic leaves. Transcriptome sequencing indicated the presence of a potexvirus in the infected samples. The complete viral genome, determined to be 6,784 nucleotides in length, excluding the poly(A) tail, contains five open reading frames and is most closely related to that of euonymus yellow vein associated virus (EuYVAV, MF078061) (41.0%). Based on the coat protein gene, this virus shares the highest sequence similarity with cymbidium mosaic virus (CyMV, EF125179), with 43.9% nucleotide and 38.8% amino acid sequence identity, respectively. Phylogenetic analysis indicated that the virus clustered with potexviruses and is most closely related to EuYVaV. This virus is a distinct member of the genus Potexvirus, for which the name "euonymus yellow mottle associated virus" (EuYMaV) is proposed. [ABSTRACT FROM AUTHOR]

A programme of field trials for the study of the winter barley–Rhynchosporium commune pathosystem is reported. The associated seedborne disease rhynchosporium leaf scald is regarded as having an important impact on barley yields. The analysis in this study relates to the impact of the seed source (commercial or farm‐saved seed) on disease incidence and to the spatial pattern of rhynchosporium leaf scald disease incidence. Disease incidence data were calculated from field data recorded as disease severity. Mean disease incidence was higher in the crops grown from farm‐saved seed than in those grown from commercial seed, although great agronomic significance cannot be attached to this result. The spatial pattern of rhynchosporium leaf scald disease incidence was characterized in terms of the binary power law (BPL) and was indicative of an aggregated pattern. Programme‐wide BPL results were described using a novel phytopathological application of a random coefficients model. These results have application in field sampling for rhynchosporium leaf scald disease. [ABSTRACT FROM AUTHOR]

Neopestalotiopsis leaf spot is a new disease on strawberry. The pathogens of the new strawberry leaf spot disease from Changping district, Beijing, Zhucheng city, Shandong Province, Baoshan city, Yunnan Province, Huizhou city, Guangdong Province and other regions were isolated and identified. The pathogen was identified by morphological analysis and ITS phylogenetic analysis. Sensitivities of 8 isolates to 8 commonly used fungicides and SYP-14288 were determined by indoor inoculation. The results showed that the pathogen was Neopestalotiopsis clavispora. SYP-14288 had a strong inhibitory effect on the mycelia growth of 8 isolates of N. clavispora, with an average EC50 value of (0.004 ± 0.002) μg/mL, which could be used as the first choice for the control of strawberry leaf spot disease. The mean of EC50 values were 0.006-0.803 μg/mL for prochloraz, azoxystrobin, tebuconazole, epoxiconazole, difenoconazole, and myclobutanil, respectively. Chlorothalonil exhibited lower toxicity. while mancozeb had the lowest inhibitory activity. Those results are important for the rational application of fungicides in the chemical control of Neopestalotiopsis leaf spot, a new disease of strawberry. [ABSTRACT FROM AUTHOR]

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Disease recognition based on crop leaf image is considerably important and significant, which is a challenging project due to the complicated nature of disease leaf image itself and the unavoidable degradations sourced from external imaging environment. In the recognition process, these traditional approaches generally stack one or more different modalities of features extracted from disease leaf images to be discriminated or trained, but do not deeply explore the relationships between features. For conquering this problem, we proposed a new crop disease recognition approach based on multi-feature sparse constrain model, which includes three steps: lesion segmentation, feature extraction and disease recognition. During the phase of disease recognition, the characteristic of our proposed is that the introduced multi-task joint sparse representation model can promote these sparse representation vectors corresponding to the different modalities of features to share similar structures to some extent with the specific styles of features extracted from the same training set. The proposed approach not only improve the efficiency significantly but also make the decision more robust. We verify the proposed approach with images of diseased cucumber, and the experiments demonstrate that our proposed method is remarkable superior to the state of the art algorithms and the correct recognition rate of our approach is 88.05%, which is higher 11.3% percentage than the benchmark of SVM method. [ABSTRACT FROM AUTHOR]

Despite its importance in providing income and food for smallholder farmers, fodder for livestock, and improving soil fertility through biological nitrogen fixation, groundnut yields are lowest on farmers' fields in Sub-Saharan Africa due to biotic and abiotic constraints. Foliar fungal diseases account for over 80% reduction in groundnut productivity in some parts of Ghana. Unfortunately, chemical control of these foliar diseases has not yielded the desired results. Meanwhile, advances in phenotyping for disease tolerance in other crops have established a strong relationship between stay-green trait and foliar disease tolerance. However, this relationship has not been explored in groundnut. This study was designed to determine the genetic control of the stay-green trait and its relationship with leaf spot disease severity in groundnut. Twenty-five advanced groundnut breeding lines with varying degrees of tolerance for leaf spot tolerance were evaluated under diseased and disease-free conditions, after which four were selected for genetic studies. Results showed significant (p<0.001) differences among the genotypes for early leaf spot (ELS), late leaf spot (LLS), leaf area under greenness (LAUG), SPAD chlorophyll meter readings (SCMR), and yield traits. Leaf spot diseases caused 4.95 t·ha−1 (64.54%) pod yield reduction in CHINESE, the widely cultivated groundnut variety in Ghana. There was a strong correlation between LAUG and ELS (r = 0.82, p<0.001) and LLS (r = 0.63, p<0.001), and genotypes that were stay-green had tolerance to both diseases. Stay-green trait in groundnut was detected to be under the control of a single recessive gene and hence may be used to select for ELS and LLS resistance. [ABSTRACT FROM AUTHOR]

The symptoms of the same tomato disease in different stages are obviously different, and different diseases show some similarities. Traditional pattern recognition methods can not reflect the dynamic changes of the pathological characterization, and the practicability is poor. To solve this problem, this paper proposed a Multi-Scale AlexNet recognition model for mobile platform based on convolutional neural network (CNN), and implemented a tomato leaf disease image recognition system for agricultural workers based on Android. Many parameters and large memory utilization of traditional AlexNet model are unfit for mobile platform, this paper adjusted the network structure of the traditional model by removing the local response normalization(LRN) layer, modifying the full connection layer, setting up different convolution kernel extraction features, designed a multi- scale recognition model based on the AlexNet. The model consists of 6 layers. It can optimize the training time and memory utilization and achieve high precision. After removing the LRN layer, there was a 30% decrease in running time. Extending the single convolution kernel into multi-scale (1 × 1,3 × 3,5 × 5,7 × 7) convolution kernel then fused at the first layer, removing full connection layer 6 and 7, and taking the place of global average pooling layer, then the model size was only 30.2 M. The forward propagation rate (FRP) and backward propagation rate (BPR) were reduced, and the global average pooling is better than the global maximum pooling on recognition accuracy. So the Multi-Scale AlexNet model used global average pooling in the 5th layer. In image preprocessing phase, in order to avoiding over fitting of the trained model caused by the unbalanced distribution of sample numbers, we had zoomed, flipped, color jittering, add noise and rotated the original pictures of dataset randomly to get the augmented dataset, and used 70% of the pictures as the train dataset and the rest as the validation dataset(20%) and test dataset(10%). These pictures were quantized to 224 × 224 dpi for Multi-Scale AlexNet training, and the original dataset and augmented dataset were used to train models. In order to validate the performance of the proposed model, comparative tests were done between Multi-Scale AlexNet and traditional pattern recognition method. It repeated 600 tests. The results showed that the CNN model achieved 92.7%, the high average recognition accuracy of each disease and each disease in the early, middle and late stages. Compared with the other CNN Net model(MobileNet, SequeezeNet, LeNet-5), the Multi-Scale AlexNet achieved the highest recognition accuracy, and reached 95.8% on the late stage disease dataset, but the SequeezeNet model used less memory. The MobileNet and SequeezeNet model reached lower recognition accuracy on the middle and late stages dataset, that because their convolution size was small. The recognition system was implemented on Android platform, and then test was done on field dataset. The results showed that the average recognition accuracy was 89.2%, its less value was due to the complex background of image. Then the system can meet the requirements of disease image recognition on mobile platform in production practice. The research results provide a method for disease image recognition based on convolution neural network, and provide a reference for automatic identification of crop diseases and engineering applications. [ABSTRACT FROM AUTHOR]

Echinochloa crus- galli (Barnyard grass) is a world’s most harmful weed species. Echinochloa crus-galli weed species compete with many economically important crops and causes serious problem in rice production. The virulent strain LD2 (leaf disease) of Curvularia lunata was screened out from 25 fungus strains isolated from the diseased leaves of barnyard grass (Echinochloa crus-galli). Greenhouse pot studies were conducted to the feasibility of the strain being as a mycoherbicide for barnyard grass control. The results of pathogenicity experiments showed that this strain was highly pathogenic to barnyard grass at the 2 to 3 leaf stages. Strain LD2 provided excellent barnyard grass control when it was applied at the concentration of 1×104, 1×106 conidia ml1. This strain was very safe to rice and the most plant species except wheat, barley and corn. Findings of this study indicated that this strain could be a potential mycoherbicide for barnyard grass control in paddy fields in the future. [ABSTRACT FROM AUTHOR]

Early and late leaf spots (LLSs) are the major foliar diseases of peanut responsible for severely decreased yield in the absence of intensive fungicide spray programs. Pyramiding host resistance to leaf spots in elite cultivars is a sustainable solution to mitigate the diseases. In order to determine the genetic control of leaf spot disease resistance in peanut, a recombinant inbred line population (Florida-07 × GP-NC WS16) segregating for resistance to both diseases was used to construct a SNP-based linkage map consisting of 855 loci. QTL mapping revealed three resistance QTLs for LLS qLLSA05 (phenotypic variation explained, PVE = 7–10%), qLLSB03 (PVE = 5–7%), and qLLSB05 (PVE = 15–41%) that were consistently expressed over multi-year analysis. Two QTL, qLLSA05 and qLLSB05 , confirmed our previously published QTL-seq results. For early leaf spot, three resistance QTLs were identified in multiple years, two on chromosome A03 (PVE = 8–12%) and one on chromosome B03 (PVE = 13–20%), with the locus qELSA03_1.1 coinciding with the previously published genomic region for LLS resistance in GPBD4. Comparative analysis of the genomic regions spanning the QTLs suggests that resistance to early and LLSs are largely genetically independent. In addition, QTL analysis on yield showed that the presence of resistance allele in qLLSB03 and qLLSB05 loci might result in protection from yield loss caused by LLS disease damage. Finally, post hoc analysis of the RIL subpopulation that was not utilized in the QTL mapping revealed that the flanking markers for these QTLs can successfully select for resistant and susceptible lines, confirming the effectiveness of pyramiding these resistance loci to improve host-plant resistance in peanut breeding programs using marker-assisted selection. [ABSTRACT FROM AUTHOR]

The research was conducted for the source of resistance against Alternaria leaf spot disease of brassica. In the current research, ten varieties/advanced lines were evaluated in 2016-17 and 2017-18 against this disease using Randomized Complete Block Design (RCBD) at the experimental research area of Oilseeds Research Institute, Ayub Agricultural Research Institute Faisalabad. During 2016, three advanced lines (RBN-13017, RBN-13022 and RBN- 13029) exhibited moderately resistant response with 22.33%, 18.42% and 13.76% disease incidence respectively under rating 2 whereas two advanced lines namely KN-294 (34.56%) and 14CBN009 (42.99%) expressed a moderately susceptible response (rating 3). Similarly, four advanced lines/varieties showed susceptible response with (66.54%), (54.28%), (64.77%) and (60.12) percent disease incidence while KJ-159 was used as spreader that expressed highly susceptible response with 92.14 % disease incidence. During 2017-18 four varieties/advanced lines namely KN-279, 14CBN001, Faisal Canola and Rohi Sarson exhibited susceptible response with (68.84%), (56.38%), (66.97%) and (58.22) percent disease incidence (rating 4) whereas two advanced lines such as KN-294 (31.86%) and 14CBN009 (40.09%) showed moderately susceptible response (rating 3). Likewise, three advanced lines exhibited moderately resistant response with 24.63%, 19.82% and 12.06% disease incidence respectively under rating 2. It was concluded that source of resistance is the most economical management strategy for the farmers against Alternaria Leaf Spot Disease of brassica. [ABSTRACT FROM AUTHOR]

A cowpea cultivar Vigna unguiculata L. Walp ‘Seonhyeon’ is a cross species between V. unguiculata ‘IT145373’ and V. unguiculata ‘IT101362’ developed at the Jeollanamdo Agricultural Research and Extension Services (JARES) in 2017. ‘Seonhyeon’ is an erect plant with an intermediate plant habit, green hypocotyls, light purple-colored corolla, heart-shaped leaflets, black seed surface, and straight, brown mature pods. The anthocyanin content of ‘Seonhyeon’ was 1,632 μg/g, and it contained seven anthocyanins, including cyanidin-3-glucoside and delphinidin-3-glucoside. The stem length of ‘Seonhyeon’ was 54 cm, which was 13 cm longer than that of the control cultivar ‘Okdang’. Its 100-seed weight was 11.8 g, which was 3.6 g lighter than that of the control cultivar. Field resistance of ‘Seonhyeon’ to leaf and systemic diseases was similar to that of the control cultivar, whereas its field resistance to lodging was slightly lower compared to that of the control cultivar. The average yield of ‘Seonhyeon’ was 2.26 ton/ha, which was 15% higher compared to that of control cultivar. Black seed coat of the ‘Seonhyeon’ cultivar is expected to contribute to species specialization as well as to development of various processed products. (Registration number: 7499) [ABSTRACT FROM AUTHOR]

Oryza sativa ‘Sinbo’ is a cultivar of japonica rice with good eating quality as well as resistance to rice dwarf virus (RDV) and bacterial blight disease (BB). It was developed in 2013 by the rice breeding team of Yeongdeok Branch, National Institute of Crop Science, RDA, Korea. This cultivar was derived from a cross between ‘Yeongdeog34‘, a cultivar with good eating quality, and ‘Saekyehwa’, a cultivar of a good plant type, in summer of 2002. A promising line (YR24264-25-3-2) selected using the pedigree breeding method was designated as ‘Yeongdeog55’ in 2010. After carrying out the local adaptability test at nine locations from 2011 to 2013, ‘Yeongdeog55’ was published under the name of ‘Sinbo’ in 2013. ‘Sinbo’ is a medium-late maturing cultivar with a short culm length of 70 cm. This cultivar is resistant to K1, K2, and K3 races of bacterial blight as well as to dwarf virus, and it is moderately resistant to leaf blast disease. The results of the panel test indicated that ‘Sinbo’ has translucent and clear milled rice kernel without white core and belly rice as well as good eating quality. The yield potential of ‘Sinbo’ was approximately 5.67 MT/ha at the ordinary fertilizer level in the local adaptability test (LAT). This cultivar could be adaptable to the middle plain, south plain, Yeongnam plain, east costal area, and south mid-mountainous area of South Korea. (Registration No. 5643) [ABSTRACT FROM AUTHOR]

Different blade species have different blade characteristics information, whether it is based on leaf information to identify tree species or accurately detect leaf diseases, image segmentation is particularly important. This paper proposes a blade image segmentation method based on the new addition algorithm, which is used to add the edge contour of the binary image extracted by the Canny detector to the original gray image, and the inverted binary image is quadratic with the first added image. Before and after adding, the image format and size of the blade image should be kept consistent, and the image addition condition can be satisfied to realize the segmentation of the blade image. The experimental results show that the method retains the complete feature information of the blade and the blade is completely separated from the background. It provides solid theoretical support for subsequent image feature extraction and tree species identification, the addition method can also be applied to other fields of image segmentation. [ABSTRACT FROM AUTHOR]

Tomato leaf curl virus (ToLCV) causes a disease of tomato (Solanum lycopersicum L.) worldwide and jeopardizes sustainable production, with yield losses up to 100%. The Tomato leaf curl disease in the Varanasi region of India is caused by Tomato leaf curl Gujarat virus (TLCGV). The ToLC disease occurrence is shifting from the rainy to the winter season that may be due to changing climate. A number of resistant genes have been identified in the wild background and a limited number of genotypes resistant to ToLCV are available in tomato. The wild species have been determined to be ToLCV resistant using morphological, biochemical and molecular markers. Tomato populations (F2, F3, Recombinant Inbred Lines) developed using wild species have been investigated using Mendelian genetics through breeding. Molecular approaches have provided opportunities in the form of linked molecular markers and loci on chromosomes to speed up, and simplify, selection of host resistance genes. However, transformation of resistant genes by genetic engineering is preferred for developing ToLCV resistant varieties. Modern techniques combined with conventional techniques offer opportunities for improving ToLCV resistance in tomato. [ABSTRACT FROM AUTHOR]

Okra (Abelmoschus esculentus (L.) Moench) is an economically important vegetable crop that is widely cultivated in the tropics for its nutritional properties. There are concerns, though, that in China, commercial okra production is at risk from an emerging leaf blight disease, that has been recently observed in Fujian Province. Fungi were isolated from diseased okra leaves collected in 2016 and 89 fungal isolates were tentatively identified as Choanephora cucurbitarum based on cultural and sporangia characters. DNA sequences of the internal transcribed spacer (ITS) region and the D1/D2 region of the large subunit (LSU) of the rRNA gene from two representative isolates (C6 and C7) were 99% identical to those of C. cucurbitarum obtained from NCBI. Phylogenetic analysis based on the ITS sequences showed that C6 and C7 clustered with C. cucurbitarum. All 89 fungal isolates were found to be pathogenic to okra leaves. We provide the first confirmation that, based on morphological, pathogenicity and phylogenetic analyses, the causal agent of leaf blight of okra in China was C. cucurbitarum. [ABSTRACT FROM AUTHOR]

Leaf blight of sunflower caused by Alternaria spp. occurs frequently in the Beijing municipality of China. A total of 482 Alternaria isolates were obtained from sunflower leaves with typical dark fleck symptoms sampled from 13 different districts in the Beijing municipality in 2014. Morphological observations and sequence analyses of the rDNA-ITS region and the histone 3 gene revealed that two Alternaria species, A. tenuissima (86.5% frequency) and A. alternata (13.5% frequency), were associated with the disease. Four isolates of A. tenuissima and six of A. alternata were pathogenic to sunflower leaves with disease incidence and disease index ranging from 50−100% and 16.7–33%, respectively. This is the first comprehensive examination of the involvement of Alternaria species in leaf blight of sunflower of Beijing, China. [ABSTRACT FROM AUTHOR]

• Dilated convolution kernel enlarges local receptive field and enhances feature extraction. • Global pooling layer reduces training parameters number and avoids overfitting problem. • Multi-scale convolutional kernels extract multi-scale features of the input image. • Improvement of recognition accuracy and robustness is verified by the experimental results. It is a challenging research topic to identify plant disease based on diseased leaf image processing techniques due to the complexity of the diseased leaf images. Deep learning models are promising for identifying plant disease based on leaf images and AlexNet is one of these models. Aiming at the problems of too many parameters of the AlexNet model and single feature scale, a global pooling dilated convolutional neural network (GPDCNN) is proposed in this paper for plant disease identification by combining dilated convolution with global pooling. Compared with the classical convolutional neural network (CNN) and AlexNet models, GPDCNN has three improvements: (1) the convolution receptive field are increased without increasing the computational complexity and without losing the discriminant formation by replacing fully connected layers with a global pooling layer; (2) dilated convolutional layer is employed to recover the spatial resolution without increasing the number of training parameters; (3) GPDCNN also integrates the merits of dilated convolution and global pooling. Experimental results on the datasets of six common cucumber leaf diseases demonstrate that the proposed model can effectively recognize cucumber diseases. [ABSTRACT FROM AUTHOR]

The French plantain cultivar, Nendran (Musa AAB) is the most widely and commercially cultivated variety of banana in Kerala. But this cultivar is highly susceptible to foliar fungal diseases especially leaf spot diseases. Among the leaf spot diseases, Sigatoka leaf spot caused by Mycosphaerella spp. poses a serious threat to banana cultivation. The studies on characterization of the pathogen associated with Sigatoka leaf spot disease complex in Kerala revealed that the predominant leaf spot disease is Eumusae leaf spot disease caused by Mycosphaerella eumusae. With an objective to develop a fungicidal recommendation for the sustainable management of this disease, a field experiment was conducted during 2016-17 at Banana Research Station, Kannara by evaluating the efficacy of six chemical fungicides viz., trifloxystrobin (25%) + tebuconazole (50%) (Nativo® - 0.4g/L), propiconazole (Tilt® - 1ml/L), copper hydroxide (Kocide® - 2g/L), pyraclostrobin (Headline® - 1g/L), hexaconazole (5%) + captan (70%) (Taqat® - 2g/L) and Bordeaux mixture (1%). All the chemical fungicides used in the study were found to be superior compared to unsprayed control. However, there was a variation in the efficacy between the treatments. The foliar application of the systemic fungicide trifloxystrobin + tebuconazole (0.4g/L) recorded the lowest per cent disease severity (PDS) of 15.43 per cent with the eighth leaf of the plant as the youngest leaf spotted (YLS) and the maximum disease development time (DDT) of 50.66 days. Among the contact fungicides evaluated, the lowest per cent disease severity of 16.65 per cent was recorded in plants sprayed with copper hydroxide which recorded DDT of 49.33 days and YLS of 7.29. The analysis of fungicide residue in the fruits revealed that there was no residue of the chemicals left in the fruit. The study revealed that four times foliar spraying of systemic fungicide, trifloxystrobin + tebuconazole (0.4g/L) or contact fungicide, copper hydroxide (2g/L) starting from the initial appearance of the disease on the lowest leaves of 75 per cent plants was safe and effective for the management of Eumusae leaf spot disease of banana. [ABSTRACT FROM AUTHOR]