Journal articles: 'Brown Blight disease' – Grafiati (2024)

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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 present 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 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.

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Brown blight disease caused by Colletotrichum species is a common and serious foliar disease of tea (Camellia sinensis). Fungal isolates from several tea plantations causing typical brown blight symptoms were identified as belonging to the Colletotrichum acutatum species complex and the Colletotrichum gloeosporioides species complex based on morphological characteristics as well as DNA analysis of the internal transcribed spacer (ITS) and glyceraldehyde 3-phosphate dehydrogenase (GAPDH). Colletotrichum acutatum, a new causal agent associated with C. sinensis, showed high phenotypic and genotypic diversity compared with the more commonly reported C. gloeosporioides. Phylogenetic analysis derived from individual and combined ITS and GAPDH sequences clearly clustered C. acutatum and C. gloeosporioides into separate species. Pathogenicity tests validated that both species were causal agents of tea brown blight disease and were highly pathogenic to tea leaves. However, the two groups of C. gloeosporioides with low levels of variability within their ITS and GAPDH regions differed in their virulence. This study reports for the first time the characterization of C. acutatum and C. gloeosporioides causing brown blight disease on tea (Camellia sinensis (L.) O. Kuntze) in China.

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Potatoes are an important crop heavily consumed by Indian food products. It is produced on a massive scale, with China, India, Russia, Poland, and the USA being the main producers. Numerous leaf diseases harm the crop during its production. A typical Indian farmer lacks the tools necessary to detect Leaf Disease before damage is done. On a dataset of potato leaf images retrieved from Kaggle, we employed the EfficientNetB0 of Deep Learning to address this problem. This model uses width scaling and resolution scaling apart from depth scaling to perform the classification. Our work mainly focuses on the diseases Early Blight and Late Blight, two serious potato diseases. Early blight Spots start off as tiny, dry, dark, and papery specks that develop into brown to black, circular to oval-shaped regions. Veins that round the spots frequently give them an angular appearance. Late blight syntoms appear as small, light to dark green and round to irregularly shaped. Water-soaked patches are the first signs of late blight. The Data Collection has 2152 pictures in total, 2000 of which are diseased and 152 of which are healthy. The deep learning model provides a testing accuracy of 99.05%, which is higher than several widely used techniques available to provide farmers with knowledge about correct diseases well in time.

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Rice crops are susceptible to disease, which causes large yield losses in many Asian countries. The influence of disease incidence and severity on grain yield and quality of the rice (Oryza sativa L., cv. BRRI dhan29) was investigated in three different locations of Chief Farm Superintendent’s (CFS) farm viz. Near Weather Yard (location-1), Near Agronomy Farm (location-2) and Near CFS farm office (location-3), Bangladesh Agricultural University (BAU), mymensingh, Bangladesh during boro season. In location-1, both brown spot and sheath blight were recorded whereas in location-2 and in location-3 only brown spot was recorded. Severity of brown spot was lowest at the location-1 and the highest at the location-3. Combined incidence of brown spot and sheath blight decreased the yield considerably whereas brown spot did not alone. Maximum severity of sheath blight was observed both in flowering and soft dough stage and minimum at maximum tillering stage. The lowest infection index of brown spot was obtained at maximum tillering stage and the highest infection index was obtained at soft dough stage whereas maximum and minimum infection index of sheath blight of rice were recorded at soft dough stage and maximum tillering stage, respectively. Aparently healthy seeds, spotted seeds, discoloured seeds, deformed seeds and chaffy grains were found among the three locations. Germination percentage was highest in healthy seeds compared to other category seeds. Alternaria padwickii, Alternaria tenuis, Bipolaris oryzae, Curvularia lunata and Fusarium semitectum were found to be associated with the seed. The highest and lowest occurrence of A. padwickii, A. tenuis, B. oryzae, C. lunata were recorded from chaffy grains and from healthy seeds, respectively. It is suggest that disease incidence and severity was gradually increased with the age of the plant and reduced yield and quality of BRRI dhan29. Int J Appl Sci Biotechnol, Vol 4(3): 311-317

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Disease surveys were conducted in rice grown districts of Libokemkem, Dera and Fogera in south Gondar zone in 2016 and 2017 cropping seasons. The study was designed to identify and record rice disease flora, their distribution in the districts, prioritize according to the importance and document for future use. Forty-six and 48 rice fields were assessed from nine Peasant Association (PA) in 2016 and 2017 cropping seasons, respectively. Rice diseases; Leaf blast, Panicle Blast, Brown spot, Sheath rot, Sheath brown rot, Sheath Blight, Bacterial blight, Rice Yellow Motile Virus, Kernel smut, Downy mildew were identified in 2016 cropping season and nine rice diseases: Leaf blast, Panicle Blast, Neck Blast, Node blast, Brown spot, Sheath rot, Sheath brown rot, Rice Yellow Motile Virus, Kernel smut were identified in 2017. The overall mean prevalence of sheath rot and sheath brown rot diseases were above 60%, while the others had prevalence below 21%. The incidences and severities of these two diseases were higher than the other diseases implying that both diseases were important. In the present studies many rice diseases were recorded in lowland ecosystem as compared to upland ecosystem. From the assessment X-jigna cultivar was more susceptible to rice disease and followed by Gumera. The results indicate that a sheath rot, and sheath brown rot, were important across the districts and years. Loss assessment studies should be initiated in order to know the yield damage caused by the diseases.

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Sheath blight caused by Rhizoctonia solani (teleomorph: Thanatephorus cucumeris) is a major cause of crop loss in intensive rice production systems. No economically viable control methods have been developed. We screened aqueous extracts of common herbal plants that could reduce sheath blight lesions and found that foliar spraying and seed soaking application of extracts of either fresh or dried leaves of Chromolaena odorata gave up to 68% reduction in sheath blight lesion lengths under controlled and semi-field conditions. The observed reductions were not dependent on growth conditions of C. odorata and rice cultivar. The effect was observed until 21 days after inoculation and was not dependent on microbial activity. Under semi-field conditions, extracts also reduced severity of other important rice diseases, i.e., blast (Pyricularia oryzae) using foliar spray (up to 45%), brown spot (Bipolaris oryzae) using seed treatment (up to 57%), and bacterial blight (Xanthom*onas oryzae pv. oryzae) using both application methods (up to 50%).

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A leaf blight disease with an incidence level of about 50% was found on Robusta banana in Guangdong province of China in September 2020. The early symptom appeared as pale gray to black brown, irregular, small, necrotic lesions mainly on the top 3–5 leaves. Severely infected leaves were withered and necrotic. Two representative fungus strains, strain L1 and strain L2, were isolated from affected banana leaves, and morphological and molecular identification analysis confirmed that the two fungi were both Alternaria jacinthicola. Many Alternaria species have been reported to cause wilting, decay, leaf blight and leaf spots on plants and lead to serious economic losses in their production, including A. alternata, causing leaf blight and leaf sport diseases on banana. The Koch’s postulates of A. jacinthicola causing the leaf blight disease was further fulfilled, which confirmed that it is the causal agent of this disease. To our knowledge, this is the first report of A. jacinthicola causing leaf blight on banana in China.

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The article presents the research data on the effect of Fusarium blight, Phoma rot, and Sclerotinia blight on the plant productivity of winter and spring rapeseed, brown mustard, and white mustard. As a result of studies, we found that Fusarium blight (the pathogens are fungi of the genus Fusarium Link) was the most harmful for the spring rapeseed, brown and white mustard – affection by it significantly decreased plant productivity. At 4 points of affection degree of plants, the harmfulness of the disease reached 71.2, 82.4, and 87.2 %, respectively. On winter rapeseed and mustard, plant productivity was considerably decreased by affection by Phoma rot in the form of a stem cancer (the pathogen is a fungus Leptosphaeria maculans (Desm.) Ces. et. De Not) and the stem form of Sclerotinia blight (the pathogen is a fungus Sclerotinia sclerotiorum (Lib.) De Bary.). The harmfulness of these diseases at 4 points of affection degree of plants reached 56.7 % and 66.7 % on rapeseed, and 56.6 % and 70.7 % on mustard, respectively.

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Blossom blight is a destructive disease of plums (Prunus salicina) when humid and temperate weather conditions occur in Chile. Disease incidence ranging from 4 to 53% has been observed. Symptoms include light brown petal necrosis, starting as light brown mottles or V-shaped necrosis at the margins of the petals, progressing to the stamen and pistils. In this study, the etiology of blossom blight of plums was determined. High- and low-sporulating isolates of Botrytis were obtained consistently from blighted blossoms and apparently healthy flowers of plums. Based on colony morphology, conidial production and molecular phylogenetic analysis, these high- and low-sporulating isolates were identified as B. cinerea and B. prunorum sp. nov., respectively. Phylogenetic analysis of the genes glyceraldehyde 3-phosphate dehydrogenase (G3PDH), heat-shock protein 60 (HSP60), and DNA-dependent RNA polymerase subunit II (RPB2) grouped B. prunorum isolates in a single cluster, distantly from B. cinerea and other Botrytis species. The phylogenetic analysis of necrosis and ethylene-inducing protein (NEP1 and NEP2) genes corroborated these results. Analysis of the internal transcribed spacer region and large-subunit (26S) ribosomal DNA and detection of Boty and Flipper transposable elements, were not useful to differentiate between these Botrytis species. Both species were pathogenic on plum flowers and the fruit of plums, apples, and kiwifruits. However, B. prunorum was less virulent than B. cinerea. These pathogens were re-isolated from inoculated and diseased tissues; thus, Koch’s postulates were fulfilled, confirming its role in blossom blight of plums. B. cinerea was predominant, suggesting that B. prunorum may play a secondary role in the epidemiology of blossom blight in plums in Chile. This study clearly demonstrated that the etiology of blossom blight of plums is caused by B. cinerea and B. prunorum, which constitute a species complex living in sympatry on plums and possibly on other stone fruit trees.

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Traditional rice varieties maintained and cultivated by farmers are the potential sources of resistant donors that can be used for breeding rice varieties with durable resistance. They possess traits potentially adaptable to a wide range of abiotic and biotic stresses. Characterization of these germplasm is essential in rice breeding varieties and provides valued information for developing new rice. In this study, a large-scale screening of 167 traditional rice varieties was carried out to identify resistance sources against blast, sheath blight and brown spot diseases of rice. The mean location severity index (LSI) of leaf blast, sheath blight and brown spot was 6.91,7.14 and 7.84, respectively. Among the varieties screened, five varieties viz., Malgudi sanna, Putta batta, Selamsanna, Sadaholga and Mysuru sanna showed resistant reaction against blast, while only one variety Putta batta showed resistant reaction against brown spot, none of the varieties showed resistant reaction against sheath blight. However, only one variety Bangara sanna-4 showed moderate resistance to the sheath blight disease. The identified resistant varieties can be used as potential source for breeding durable resistant varieties in the future crop improvement programmes.

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Demand for organically grown fruit, including sour cherry, is rising in Europe and the United States, but the limited tools for disease management have not been thoroughly investigated. In this study, management of brown rot blossom blight, caused by Monilinia laxa, was examined for organic sour cherry production in Hungary. Combinations of sanitation practices and fungicide treatments, including copper hydroxide, lime sulfur, and micronized and nonmicronized wettable sulfur, were investigated in 2 years and two cultivars. The effect of fungicide treatments on yield and phytotoxicity on spur-leaf clusters was also determined. Among fungicide treatments suitable for organic production, copper hydroxide and lime sulfur alone or in combination with micronized wettable sulfur were most effective for blossom blight control when applied twice (at closed blossom and full bloom) or three times (at closed blossom, full bloom, and petal fall) during bloom. Both treatments were not as effective as the conventional standard and caused more damage on spur-leaf clusters during wet weather conditions, but significantly increased crop yield compared with the untreated control or wettable sulfur treatments. Micronized and nonmicronized sulfur applied up to three times during bloom were equally effective, did not impact yield, were not phytotoxic, and reduced blossom blight compared with the untreated control. Sanitation (the removal of blighted twigs and mummified fruit) reduced blossom blight in both cultivars compared with nonsanitized plots when disease pressure was high. The need for an integrated approach to effectively manage blossom blight in organic sour cherry production is discussed. This is the first in-depth characterization of cultural and chemical brown rot blossom blight control options for organic sour cherry production.

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Abstract: This paper presents a deep learning project that addresses Rice Leaf Disease Detection using convolutional neural Networks (CNN). We develop a novel deep learning model using a computer vision by image processing which detect the diseases like leaf smut, Brown spot, Bacterial leaf blight and with ReLU activation function by using adam optimization algorithm which evaluate its performance on rice leaf disease which shows the confidence.

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Dry beans may be affected by a number of distinct diseases, including four bacterial diseases often found occurring simultaneously in a complex. Three diseases are commonly encountered — common bacterial blight, halo blight, and bacterial brown spot — with a fourth disease (bacterial wilt) re-emerging in the Central High Plains after an absence of more than 30 years. The information in this guide may be used to identify and distinguish between the various bacterial diseases that may be encountered in dry bean production. Accepted for publication 14 October 2006. Published 25 January 2007.

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Today, the area under strawberries is growing every year. Because it is valued for its unpretentiousness to soil conditions, early and rapid fruit ripening, stable yields and resistance to low temperatures. But researchers note a reduction in yields in areas occupied by industrial strawberry plantations in horticultural farms due to the negative impact of the spread of fungal diseases. Gray mold (Botrytis cinerea Pers), verticillium wilt (Verticillium albo-atrum Reinke et Berth.), white spot (Ramularia tulasnei Sacc) and brown spot (Marssonina potentillae P. magn. f. Fragaria Man.), late wilting (Phytophthora fragariae Hick), late blight (Phytophthora cactorum (Leb. et Cohn.) are the dominant fungal diseases of garden strawberries in Ukraine. White spot affects the leaves, petioles, peduncles, sepals and stalks of garden strawberries. When affected by the disease, the appearance of reddish-brown spots is observed, which eventually acquire a white color and a dark red rim appears around. Brown spot mainly damages the leaves of strawberries, which affects the photosynthesis of the plant. Signs of this disease are the appearance of light olive spots, which later turn yellow, and on the underside of the leaf a plaque from light gray to green-brown color is formed. Gray mold fungus affects the leaves, flowers and fruits of garden strawberries. A "fluff" of conidia is formed on berries. They soften, change color to brown and rot. Infection of strawberries with verticillium wilt occurs through the root system. After penetration of the pathogen into the plant, the formation of chlorotic spots is observed. Eventually, the leaves turn yellow, dry up, the conductive tissues are destroyed and the plant dies. Two forms of phytophthora wilting of garden strawberries are described. In the first form, the color of the leaves changes from red to yellow-brown, which then withers and dries. The plant itself lags behind in growth. The second form of the disease affects the root system. The roots turn gray or brown and die. Signs of late blight rot are visible on the roots of strawberries in late autumn, and on the aboveground organs in the spring. Brown ring spots are formed on the root neck, which turn into rot. Necrosis appears on the stem and veins of the leaves, after which the young leaves slow down their growth and dry up. When the plant is affected by pathogens, there is a decrease in yield: white spot causes 10–30 %, brown spot – up to 50 %, gray mold – 30 %, wilting (late blight, verticillium wilt) and late blight – up to 50–60 %. Therefore, since fungal diseases cause a decrease in yield and quality of the species composition of strawberries, it is necessary to develop a system of protection, using agronomic, biological and chemical methods of control.

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There are two records of brown spot needle blight caused by <I>L. acicola</I> in the Czech Republic up to date. Disease was first reported on June 2007 in National Nature Reserve (NNR) Červená Blata, South Bohemia. A more recent discovery of <I>L. acicola</I> took place on August 2008 in the NNR Borkovická Blata. The disease was observed on 10-60 year old <I>Pinus rotundata</I>. Both locations with infected trees are situated inside nature conservation sites under strict protection regimes that are located approximately 50 km apart. In both sites, <I>L. acicola</I> occurred simultaneously with <I>Dothistroma septospora</I>, the red band needle blight causal agent on Scots pine (<I>Pinus sylvestris</I>), bog pine (<I>P. rotundata</I>) and their hybrid (<I>P. × digenea</I>). However, infections of both diseases on the same tree have not yet been observed.

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Bacterial panicle blight, bacterial leaf streak, and bacterial brown stripe are common bacterial diseases in rice that represent global threats to stable rice yields. In this study, we used the rice variety HZ, Nekken and their 120 RIL population as experimental materials. Phenotypes of the parents and RILs were quantitatively analyzed after inoculation with Burkholderia glumae, Xanthom*onas oryzae pv. oryzicola, and Acidovorax avenae subsp. avenae. Genetic SNP maps were also constructed and used for QTL mapping of the quantitative traits. We located 40 QTL loci on 12 chromosomes. The analysis of disease resistance-related candidate genes in the QTL regions with high LOD value on chromosomes 1, 3, 4, and 12 revealed differential expression before and after treatment, suggesting that the identified genes mediated the variable disease resistance profiles of Huazhan and Nekken2. These results provide an important foundation for cloning bacterial-resistant QTLs of panicle blight, leaf streak, and brown stripe in rice.

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Breeding of grain crops for phytoimmunity in the FSBSU FASC of the Northeast is carried out in the conditions of natural and artificial epiphytotics. Every year, more than 1000 samples of winter rye, spring soft wheat, barley and oats of their own breeding and from the VIR collection are studied. In winter rye, studies are conducted on snow mold, root rot, powdery mildew, brown and stem rust, septoria blight, fusarium head blight, and ergot; in spring wheat – on root rot, septoria blight, fusarium head blight, powdery mildew, brown rust, loose smut; in barley – on root rot, net, dark brown blotch and stripe disease, loose smut; in oats - on red-brown blotch, root rot, crown rust, panicle fusarium and loose smut. Resistant samples detected on infectious backgrounds will be included in the breeding process as sources of the trait. With the participation of source genes, new varieties of winter rye were created, Snezhana, Grefinya, and others, which are being studied at different breeding stages. Long-term studies (2014-2020) on infectious and provocative backgrounds among the breeding material of the FASC of the Northeast and collection samples of spring soft wheat, oats, barley revealed sources of nonspecific resistance (6-9 points). They are used in crossbreeding programs with the best varieties to obtain high-yielding and resistant to biotic stressors hybrids that are being studied at different breeding stages.

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The effect of barley-legume intercrop in an organic farming system on disease incidence was investigated. The legumes<br />were lupin, faba bean and pea. Diseases were detected on pea and barley. On pea, only ascochyta blight (Ascochyta pisi)<br />was observed. When either pea variety was intercropped with barley, the level of ascochyta blight was reduced. Net<br />blotch (Pyrenophora teres), brown rust (Puccinia recondita) and powdery mildew (Blumeria graminis f.sp. hordei) (in<br />order of incidence) were monitored on barley between flag leaf emergence and heading. The levels of all three diseases<br />were reduced in every intercrop treatment compared to the barley monocrop. However, this reduction was only statistically<br />significant in the pea treatments for net blotch.

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A severe epidemic of a leaf blight of cotton occurred in the state of Paraná, Brazil, during 1994 and 1995, causing up to 100% yield losses in some commercial fields of cultivar Paraná 3. The severity of the disease among fields was variable and cultivar-dependent. Attempts were made to identify the organism causing the leaf blight symptoms, which were characterized as circular to irregular dark brown to black spots turning reddish brown with age and varying between 2 and 10 mm in diameter. The older lesions showed cracks and/or holes in the center. Severely diseased leaves dried rapidly and abscised. Fructifications of a fungus in the genus Stemphylium were observed on young, as well as on old, lesions. The Stemphylium sp. was consistently isolated on potato dextrose agar from disease samples collected from five cultivars in 14 locations. In inoculation tests, the Stemphylium isolates from cotton were highly aggressive to cotton, tomato, potato, and blue lupines; whereas an isolate of S. solani from tomato was highly aggressive on tomato and potato but less aggressive on cotton. On the basis of its morphological, cultural, and pathogenic characteristics, the principal pathogen causing leaf blight symptoms was identified as Stemphylium solani. Epidemics caused by S. solani on cotton have not been reported previously in commercial cotton cultivation.

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Stone fruit are an economically important group of specialty fruit crops in the United States. Species of the fungal genus Monilinia are some of the most important pathogens of stone fruit worldwide. These pathogens cause blossom blight, shoot blight, and brown fruit rot in temperate production regions. The most common species of Monilinia pathogenic on stone fruit include Monilinia fructicola, M. laxa, M. fructigena, and M. polystroma. Presently, neither M. polystroma, the causal agent of “Asiatic brown rot”, nor M. fructigena, one of the causal agents of “European brown rot”, have been reported in North America. Interestingly, both species can also cause brown rot of apple, which is densely planted in the eastern United States. This recovery plan was produced as part of the National Plant Disease Recovery System (NPDRS), called for in Homeland Security Presidential Directive Number 9 (HSPD-9) to ensure that the tools, infrastructure, communication networks, and capacity required to mitigate the impact of high-consequence plant disease outbreaks are such that a reasonable level of crop production is maintained. It is intended to provide a brief primer on the disease, assess the status of critical recovery components, and identify disease management research, extension, and education needs.

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A blight (wet rot) of petunia (Petunia ×hybrida Hort. Vilm.-Andr.) was observed in a wholesale propagation nursery in Baton Rouge, LA in September 2002. The grower reported that plants wilted and then completely rotted. The disease occurred during a period of hot, humid, and cloudy weather. Approximately 100 flats of flowering-age plants of cvs. Rose and White Madness were destroyed. No fungal sporulation was noticed on dead plants, but occasional strands of white mycelium were observed. The grower's use of azoxystrobin, iprodione, and thiophanate methyl plus mancozeb fungicides during current and past outbreaks of this disease did not prevent disease spread, but disease activity stopped after temperature and humidity dropped in early October. A fungus that produced white aerial mycelia that later developed light yellow areas and also black aerial spore masses was consistently isolated from diseased tissue placed on acidified potato dextrose agar (APDA). The fungus was identified as Choanephora cucurbitarum (Berk. & Ravenel) Thaxt. on the basis of cultural and morphological characteristics (3). Sporangiola were ellipsoid, pale brown to reddish brown with distinct longitudinal striations and measured 15 to 20 × 9 to 14 μm. Sporangiospores were broadly ellipsoid, pale brown to reddish brown, indistinctly striate with fine, hyaline polar appendages, and measured 16 to 34 × 7 to 12 μm. Spore measurements were within the range previously given for C.cucurbitarum (3). Pathogenicity tests were performed by misting a mixture of sporangiola and sporangiospores (25,000 to 70,000 per ml of water taken from 7- to 10-day-old cultures grown on APDA) on flowering-age petunia plants (cvs. Rose Madness, White Madness, and Dreams Pink). Tests were repeated twice. Inoculated plants and uninoculated control plants (2 to 4 of each treatment in each test) were held in a dew chamber at 28°C for 48 h and then moved to a greenhouse. Within 48 h after inoculation, plants developed water-soaked lesions on flowers, leaves, and stems, then wilted and rotted. Uninoculated plants remained disease free except for several that developed disease symptoms in the first test, apparently from the presence of natural inoculum on healthy-appearing plants that were obtained from the nursery where the disease was found. Koch's postulates were completed by reisolation of the pathogen from diseased inoculated plants. C. cucurbitarum (1) and C. infundibulifera (Curr.) Sacc. (2) have been reported to cause flower blight of petunia in the United States and whole plant blight (wet rot) of petunia in Japan (4). To our knowledge, this is the first report of C. cucurbitarum causing whole plant blight of petunia in the United States. References: (1) M. L. Daughtrey et al. Choanephora wet rot of poinsettia. Page 15 in: Compendium of Flowering Potted Plant Diseases. The American Phytopathological Society, St. Paul, MN, 1995. (2) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, St. Paul, MN, 1989. (3) P. M. Kirk. Mycological Paper 152:1, 1984. (4) J. Takeuchi and H. Horie. Jpn. J. Phytopathol. 66:72, 2000.

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Fire blight of pome fruit cultures is a dangerous quarantine disease of pome and ornamental plants of Rosaceae, caused by a Gram-negative bacterium Erwinia amylovora. For the study of the fire blight distribution and timely establishment of the threat of endemic apple species Malus sieversii infection a phytopathological study of wild fruit forests and cultural plantations of apple (Malus spp.) was carried out in Almaty region. 263 samples were collected from wild plants without visible symptoms and cultivated plants with symptoms of a fire blight - brown and necrotic young shoots that have a characteristic "shepherd's crook" shape, blackened leaves and ovaries remaining on the affected shoots, and samples from trees with manifestations of the disease had previously been noted were collected as well. Screening of all received samples was carried out based on PCR analysis and revealed 23 positive results. Phytopathological observations and the results of PCR analysis allowed identification of the infection’s source and distribution, as well as assessment of the current state of the studied areas of wild fruit forests and adjacent cultural apple plantations in Almaty region for the presence of fire blight’s infection agent.

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Withania somnifera (L.) Dunal, a potential medicinal plant used for the treatment of nervous disorders, intestinal infection, leprosy, and cancer, is a perennial herb belonging to Solanaceae and distributed throughout the drier parts of India. Leaf blight disease of this plant generally occurs during March in various districts of South Bengal, India. At the initial stage of infection, symptoms appear as small, light brown spots, gradually becoming irregular, dark brown, concentrically zonate with a diffuse margin, frequently surrounded by light yellow haloes, conspicuous brownish concentric rings in the advance stage of infection. A species of Alternaria was isolated from the lesions. The pathogen was isolated on potato dextrose agar (PDA) media. On PDA, the fungus grew slowly with colonies reaching approximately 35 to 40 mm in diameter in 7 days when incubated at 30°C. Conidiophores arose singly or in groups, straight or flexous, cylindrical, septate, pale to olivaceous brown, as much as 155 μm long, 4 to 5.5 μm thick; conidia were straight, obclavate, pale olivaceous brown, smooth, with up to 15 transverse and rarely 1 or 2 longitudinal or oblique septa and measured 50 to 115 × 5 to 10 μm. Pathogenicity tests were carried out three times on 6-month-old plants (n = 10). Plants were sprayed with a conidial suspension of 105 conidia/ml; control plants were sprayed with sterilized water. Plants were covered with polyethylene bags for 10 days. Disease symptoms appeared after 12 ± 1 day after inoculation. Symptoms on the leaves were similar to those of a naturally occurring diseased plant. The fungal pathogen was consistently reisolated from inoculated plants. The pathogen was identified as Alternaria dianthicola and further confirmed by the Agharkar Research Institute, Pune, India. A literature survey reports the occurrence of some fungal diseases (1), but to our knowledge, this is the first report of A. dianthicola on W. somnifera. References: (1) P. Sinha et al. Page 14 in: Recent Progress in Medicinal Plants. Vol. 6 Diseases and their Management. Sci Tech Publishing LLC, Houston, TX, 2000.

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Endive (Cichorium endivia) and escarole (broad-leaf type of C. endivia) are two of the many leafy vegetables produced commercially in coastal California. For several years, both crops have been affected by a disease that causes soft, watery, brown leaf decay. In the tightly appressed heads of endive and escarole plants, decay generally spreads in a concentric circle, resulting in circular whorls of brown, rotted leaves within diseased heads. Such symptoms make the heads unmarketable. In the Salinas Valley (Monterey County), the disease was much more prevalent during 1998, when weather was affected by “El Niño.” Rhizoctonia solani was isolated consistently from symptomatic leaves of both endive and escarole. Pathogenicity was tested by placing two agar plugs of representative isolates inside the leaf whorls of 15 potted plants each of endive (cv. Tres Fine Maraicchere) and escarole (cv. Full Heart). Watery, brown leaf decay, similar to symptoms observed in the field, occurred on all plants within 7 days after inoculation, and R. solani was reisolated. Control plants, treated with sterile agar plugs, did not develop disease. Tests were repeated, and results were similar. Anastomosis-group testing revealed that four endive isolates belonged to AG2-2 (1). This appears to be the first report of leaf blight of endive and escarole caused by R. solani in California. Reference: (1) Sneh et al. 1991. Identification of Rhizoctonia Species. The American Phytopathological Society, St. Paul, MN.

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Woody ornamental cover plants of Japanese pachysandra (<i>P. terminalis</i> S. et Z.) are planted in parks and gardens in the Czech Republic. A serious disease of these plants is Volutella leaf blight and stem canker caused by the fungus <i>Pseudonectria pachysandricola</i> (anamorph <i>Volutella pachysandricola</i>). It was described by DODGE (1944) in the United States and appeared in Europe in the 1980s. Volutella pachysandricola was isolated from Japanese pachysandra (<i>P. terminalis</i> cvs. Green Carpet and Variegata) from leaf spots and stem and stolon cankers in Brno in 2000&minus;2003. The tan or brown spots with brown margins, often with concentric zones, develop on infected leaves. Stem and stolon cankers appear as water-soaked diseased areas, the stem often turns brown, shrivels and girdles. The infection often begins in damaged or senescent plant parts and spreads into the healthy tissues. Pink-orange sporodochia with spores form on newly killed stems and leaves during humid spring and summer periods. Ascospores develop in red-orange perithecia on the same tissues.

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Plant diseases pose a significant threat to agricultural productivity and food security in Bangladesh. In this research, we address the challenge of timely and accurate plant disease detection through the application of transfer learning with deep neural models. We curated a diverse dataset comprising 18 categories of plant leaf images, including Bell pepper Bacterial spot, Bell pepper Healthy, Peach Healthy, Potato Early Blight, Rice Leaf Blast, Rice Healthy, Rice Brown Spot, Potato Healthy, Peach Bacterial spot, Corn Blight, Potato Late blight, Corn Healthy, Tomato Bacterial spot, Strawberry Leaf Scorch, Tomato Early blight, Tomato Early blight, Strawberry Healthy, and Tomato Healthy. The dataset represents the most prevalent plant diseases observed in the Bangladeshi context. We employed three state-of-the-art deep learning algorithms, EfficientNetV2M, VGG-19, and NASNetLarge, to develop robust plant disease detection models. Through transfer learning, these pre-trained models were fine-tuned on our specialized dataset to adapt them for the task at hand. The performance evaluation revealed impressive results, with EfficientNetV2M achieving an accuracy rate of 99%, VGG-19 achieving 93%, and NASNetLarge attaining 83% accuracy. The high accuracy of EfficientNetV2M showcases its exceptional capability in accurately classifying plant diseases prevalent in Bangladesh. The success of these deep neural models in detecting various plant diseases signifies their potential in revolutionizing plant disease management and enhancing agricultural practices. Our research contributes valuable insights into the effective use of transfer learning for plant disease detection and emphasizes the significance of dataset curation for improved model performance. The developed models hold promise in providing timely and precise disease diagnosis to farmers and agricultural professionals, thereby facilitating prompt interventions and minimizing crop losses. Future research can explore the integration of these deep neural models into practical agricultural tools, enabling real-time disease detection and offering substantial benefits to the agricultural industry in Bangladesh.

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The article presents the research on breeding and chemical methods of brown mustard sowings from Fusarium blight in the conditions of the central zone of the Krasnodar region. We evaluated mustard variety samples affected by the disease on a natural infectious background during the growing season. As a result, for 4 years we selected mustard breeding material resistant to Fusarium blight, which exceeds the productivity and oil content of the standard variety Yunona by 0.20-0.26 t/ha and 2.0-2.7 %, respectively. We tested systemic chemical fungicides from the triazoles and strobilurins groups in a chemical method study. We determined the fungicide with the active ingredients azoxystrobin 120 g/l + tebuconazole 200 g/l, SC at the application rate of 1.0 l/ha which effectively decreases the spreading and development of Fusarium blight on mustard when treating plants at the stalking stage. The biological effectiveness of the preparation was 82.4 %, the seed yield significantly exceeded the control (by 0.36 t/ha). Thus, it is recommended to use both breeding and chemical methods of sowings protection against the disease to effectively decrease the harmfulness of Fusarium blight on mustard.

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Leatherleaf fern (<i>Rumohra adiantiformis</i>) is an important ornamental plant in Indonesia and global. Green fern leaves with bold dark green color with long shelf-life, attract florists as decoration. Indonesia is one important leatherleaf fern exporters, however currently an outbreak of leaf blight decreased production significantly. Initial symptom was reddish brown spots from edge of leaf, which was gradually followed by dark-brown necrotic lesions causing leaf blight and dried. This is a study to do Koch-Postulate approach and molecular identification, to identify the pathogen of the “new emerging disease” reported. Based on multigene analysis using primers from ITS, β-tub and tef1-α gene markers, the pathogen was identified as <i>Neopestalotiopsis</i> sp. All sequences have been deposited in GenBank with accession number of OR905551 (ITS), OR899817 (ß-tubulin) and OR899816 (TEF). This Neopestalotiopsis leaf blight causes an emerging concern in leatherleaf fern in Indonesia and global biosecurity because it infected an export commodity.

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A decision support system for cereal diseases and late blight of potatoes has been developed at the Chair of Phytopathology,<br />Technische Universität München. The Wheat and Barley Prognosis System has been in use for many years by the<br />Bavarian official advisory service. It is based on an exact diagnosis and established biological thresholds influenced by<br />weather. Certain fungicides are recommended also covering diseases which have not reached the threshold. Diseases under<br />consideration are eye spot disease, powdery mildew, Septoria leaf blotch, Septoria leaf and glume blotch, tan spot, brown<br />and yellow rusts.The PhytophthoraModel Weihenstephan consists of two parts, weather based prognosis and monitoring in<br />the unsprayed control plots. Spraying recommendations are given based on the results of the above-mentioned parts and<br />considering cultivar behaviour and blight development in the field. The first spraying in the season as well as the timing<br />of the following ones are crucial. This model does not give any recommendations regarding which active ingredient should<br />applied. However there is a distinction made with regard to contact (protective) fungicides and systemic fungicides. The<br />PhytophthoraModel Weihenstephan has been in use for several years in Germany as well as in Austria.

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The sheath blight disease of rice caused by Rhizoctonia solani is an economically important disease in India. A survey was carried out to find the disease severity of sheath blight of rice and collected the disease samples from the different locations of Chhattisgarh. Fifty eight isolates of R. solani collected from various locations of Chhattisgarh were studied for their morphological and cultural variation. Cultural and morphological parameters of each isolate like growth pattern of mycelium, colony colour, Colony growth diameter (mm) at different intervals was recorded after inoculation of R. solani on to the sterilized PDA in 90 mm Petri plates incubated at 28 ± 2 0C in B.O.D incubator after 15 days [1]. The isolates were assigned code numbers such as RS1, where "RS" named Rhizoctonia solani and "1" denote the serial number of the isolate. The R. solani isolates RS1, RS2, RS3, RS4, RS5, RS12, RS19, RS34, RS50 and RS57 were recorded as fast growing isolates. The color of the fungal colony was varied from light brown to dark brown.

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Abstract Stemphyllium leaf blight (SLB) is one of the diseases that cause losses in shallots. This study aims to detect the presence of SLB disease and determine the percentage of disease incidence and severity in West Sumatra. The study used survey methods, sample collection, and disease measurement in three shallot production centers in West Sumatra districts, namely Solok, Agam, and Tanah Datar. The damage caused by this disease is determined by measuring the percentage of disease incidence and severity. Infected plants were isolated to identify the cause of the diseases. The survey results have found symptoms of SLB which has never been reported before. Symptoms on the leaves are small round spots that coalesce to form a blight which then develops into a brown lesion and turns black in the center of the lesion due to sporulation over time. The disease incidence was 12.15%, and the severity was 5.97%. Based on morphological identification, microscopy, and pathogenicity tests, it was found that the cause of this disease was Stemphyllium sp. It is the first Stemphyllium sp. report on shallots in West Sumatra.

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Common bacterial blight (CBB), bacterial brown spot (BBS), and halo blight (HB), incited by the bacterial pathogens Xanthom*onas campestris pv. phaseoli (Smith) Dye, Pseodomonas syringae pv. syringa, and Pseudomonas syringae pv. phaseolicola, respectively are important diseases of common bean. In addition three fungal pathogens, web blight (WB) Thanatephorus cucumeris, rust Uromyces appendiculatus, and white mold (WM) Sclerotinia sclerotiorum, are also destructive diseases attacking common bean. Bean common mosaic virus is also one of most major virus disease. Resistance genes (QTLs and major genes) to three bacterial (CBB, BBS, and HB), three fungal (WB, rust, and WM), and one viral pathogen (BCMV) were previously mapped in two common bean populations (BAC 6 × HT 7719 and Belneb RR-1 × A55). The objective of this research was to use an integrated RAPD map of the two populations to compare the positions and effect of resistance QTL in common bean. Results indicate that two chromosomal regions associated with QTL for CBB resistance mapped in both populations. The same chromosomal regions associated with QTL for disease resistance to different pathogens or same pathogens were detected in the integrated population.

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Web (aerial) blight was observed in field plots of Catharanthus roseus (L.) G. Don (Madagascar periwinkle) during three consecutive summers at the Burden Research Center in Baton Rouge. Leaf spots formed first, followed by a general blighting of leaves and stems that resulted in circular areas of dead plants in the plots. Dead leaves were matted together but remained attached to plants. Mycelia, and occasionally small, brown sclerotia (1 to 3 mm) were observed on blighted foliage. During the first year, only prostrate-growing cultivars belonging to the Mediterranean series of C. roseus were infected, but in 2001 and 2002 upright-growing cultivars as well as those with prostrate growth habit became infected. The disease occurred in July and August during periods of hot, humid, and rainy weather. Among 52 cultivars in the 2001 trial, only ‘Tropicana Pink’, ‘Tropicana Rose’ and ‘Stardust Orchid’ were disease free. A Rhizoctonia sp. was consistently isolated from diseased plants and further characterized as R. solani Kühn AG-1 based on its multinucleate cells and hyphal anastomosis with several AG-1 tester isolates. On potato dextrose agar, colonies displayed morphologies with characteristics of AG-1 IA and AG-1 IB, therefore, identification to AG subgroup was not made. Mature colonies ranged from light tan to brown and produced sclerotia, individually or in clumps, at the edge of the culture dish. Pathogenicity tests were performed by placing agar blocks, taken from the margins of 7-day-old cultures, on stems of eight healthy Madagascar periwinkle plants (15 to 20 cm tall). Inoculated and noninoculated control plants were held in a dew chamber at 26°C for 3 days and then moved to a greenhouse. Leaves on all inoculated plants developed water-soaked spots that turned dark brown or black prior to death, whereas noninoculated plants remained healthy. R. solani was reisolated from inoculated plants and its cultural characteristics were similar to those of the original isolate. Web blight occurs in Louisiana on Madagascar periwinkle used as landscape bedding plants, but has not been observed on container-grown plants. Web blight caused by R. solani AG-1 was previously reported on Madagascar periwinkle from Alabama (1). R. solani AG-1 has been reported previously as causing web blight in Louisiana on rosemary (2), dianthus (4), and verbena (3). To our knowledge, this is the first report of web blight on Madagascar periwinkle (C. roseus) in Louisiana. References: (1) A. K. Hagan and J. M. Mullen. Plant Dis. 77:1169, 1993. (2) G. E. Holcomb. Plant Dis. 76:859, 1992. (3) G. E. Holcomb and D. E. Carling. Plant Dis. 84:492, 2000. (4) G. E. Holcomb and D. E. Carling. Plant Dis. 84:1344, 2000.

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When detached sour cherry (Prunus cerasus) blossoms were inoculated with conidia of Monilinia fructicola and subjected to a standard 8-h wetting treatment at 20°C, blossom blight incidence was proportional to relative humidity (RH) when RH was held constant during the subsequent 6-day incubation period (frequency = 1.0 at the maximum RH of 92%; frequency = 0.38 at the minimum RH of 57%). Similarly, when a primary incubation period at 87% RH was followed by a secondary incubation period at 54% RH, blossom blight incidence was proportional to the number of hours at the higher level (frequencies of 0.94, 0.80, and 0.38 with primary incubation periods of 6 days, 36 h, and 12 h, respectively). When intact blossoms on potted trees were exposed to common inoculation and wetting treatments, disease incidence was consistently high on trees that subsequently were incubated in a controlled environment chamber (20°C, 90 to 95% RH) but was extremely variable when trees were incubated under variable ambient conditions. Ambient incubation temperature had little effect on disease incidence 9 days after inoculation, whereas ambient RH had a pronounced effect: the frequency of blighted blossoms was 0.53 to 0.61 when the number of hours at RH >90% was approximately two to six times that at RH <60%, whereas this frequency was only 0.02 to 0.07 when the number of hours at RH >90% was approximately one-third the number at RH <60%. After 48 h at a constant RH of 89 or 57%, the water potential of excised uninoculated blossoms was -1.15 and -1.93 MPa, respectively; however, growth of M. fructicola on osmotically adjusted potato dextrose agar was unaffected by changes in water potential within this range. Thus, although RH during incubation has an important influence on blossom blight development, the causal mechanism remains uncertain.

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In this contribution actual results of the Czech national ring tests of disease resistance in wheat are presented that are performed at 3&ndash;5 locations each year. Special attention was paid to possibilities of increasing resistance to rusts, powdery mildew, Fusarium head blight and brown leaf spot diseases. New sources of resistance to the above-mentioned diseases were detected and described. Achievements and prospects of wheat breeding for resistance to these diseases, as well as to other important diseases and pests (common and dwarf bunt, eyespot and stem base diseases, barley yellow dwarf virus, orange wheat blossom midge) are discussed.

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Despite fungal diseases affecting the aerial parts of cassava (Manihot esculenta Crantz) and causing significant yield losses, there is a lack of comprehensive studies assessing resistance in the species’ germplasm. This study aimed to evaluate the phenotypic diversity for resistance to anthracnose disease (CAD), blight leaf spot (BliLS), brown leaf spot (BLS), and white leaf spot (WLS) in cassava germplasm and to identify genotypes suitable for breeding purposes. A total of 837 genotypes were evaluated under field conditions across two production cycles (2021 and 2022). Artificial inoculations were carried out in the field, and data on yield and disease severity were collected using a standardized rating scale. The top 25 cassava genotypes were selected based on a selection index for disease resistance and agronomic traits. High environmental variability resulted in low heritabilities (h2) for CAD, WLS, and BLS (h2 = 0.42, 0.34, 0.29, respectively) and moderate heritability for BliLS (h2 = 0.51). While the range of data for disease resistance was narrow, it was considerably wider for yield traits. Cluster analysis revealed that increased yield traits and disease severity were associated with higher scores of the first and second discriminant functions, respectively. Thus, most clusters comprised genotypes with hybrid characteristics for both traits. Overall, there was a strong correlation among aerial diseases, particularly between BLS and BliLS (r = 0.96), while the correlation between CAD and other diseases ranged from r = 0.53 to 0.58. Yield traits showed no significant correlations with disease resistance. Although the mean selection differential for disease resistance was modest (between −2.31% and −3.61%), selection based on yield traits showed promising results, particularly for fresh root yield (82%), dry root yield (39%), shoot yield (49%), and plant vigor (26%). This study contributes to enhancing genetic gains for resistance to major aerial part diseases and improving yield traits in cassava breeding programs.

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Late blight is a highly destructive disease primarily affecting potato (Solanum tuberosum) and tomato (Solanum lycopersicum) and some other closely related crops such as aubergine, pepper, solanaceous weeds such as nightshade species, wild tomato etc. This disease is caused by fungus-like organism oomycetes also known as water mold called Phytophthora infestans. Whereas early blight of potato and tomato are caused by fungus Alternaria solani and Alternaria tomatophila respectively. Heinrich Anton De Bary, the father of modern plant pathology studied the epidemics of Late Blight in 1863 and renamed the causal organism Phytophthora infestans (infectious plant destroyer). The disease is severe in areas with high humidity and rainfall and spreads through wind, rain, or contaminated plant material capable of causing entire crop failure if left uncontrolled. Late blight affects foliage, fruit, and tuber and its symptoms include dark, water-soaked lesions on the stem, leaves, and fruit which can rapidly develop into brown, necrotic areas ultimately leading to plant death. Control measures for late blight includes crop rotation, the use of resistant varieties and the application of fungicides. However, the emergence of more virulent strains of Phytophthora infestans and the development of resistance to fungicide application pose ongoing challenges to effective disease management. This paper reviews the current knowledge on management strategies for late blight focusing on integrated disease management approaches. Furthermore, the challenges and prospects of integrated management strategies are discussed.

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One of the most serious needle diseases that affect pines (Pinus spp.) is Dothistroma needle blight (DNB). Two species of fungi are responsible for causing this disease (Barnes et al. 2004). These are Dothistroma septosporum (teleomorph: Mycosphaerella pini) that has a worldwide distribution and infects a wide range of Pinus spp. and D. pini (teleomorph unknown), which has thus far been reported only from the North-Central U.S.A. on the non-native Pinus nigra (Barnes et al. 2004). In recent years, there have been increasing numbers of reports of DNB from new hosts and new geographic regions of the Northern Hemisphere (Bradshaw 2004, Bednárová et al. 2006). Moreover, there has been an increase in the intensity of this disease in some parts of Europe and North America (Koltay 2001, Aumonier 2002, Brown et al. 2003, Jankovský et al. 2004, Woods et al. 2005).

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Brown rice is a type of rice that has many benefits for the health of the body. The main diseases that attack many rice plants and cause a decrease in production include bacterial leaf blight (HDB) caused by the bacterium Xanthom*onas oryzae. One alternative to control HDB is to use antagonistic agents, namely endophytic bacteria. This study aims to examine the ability of endophytic bacterial isolates from wetlands and the effect of application time in suppressing the intensity of bacterial leaf blight and to determine its effect on the growth of brown rice plants. There were 2 isolates of endophytic bacteria tested in this study, namely isolates of root origin (AKL) and isolates of stem origin (BLR) isolated from karamunting plants. This study used a completely randomized design (CRD) consisting of 5 treatments and 4 replications. The treatment used in this study was only the pathogen Xanthom*onas Oryzae (control), soaking seeds with endophytic bacteria from roots, soaking seeds with endophytic bacteria from stems, soaking seeds + application when transplanting with endophytic bacteria from roots and seed soaking + application when transplanting Plant with stem-origin endophytic bacteria. Treatment of endophytic bacteria on brown rice seeds and application during transplanting was able to reduce the intensity of bacterial leaf blight (X. oryzae) with a disease intensity of 83% and an effectiveness of 15.6%. Treatment of endophytic bacteria on rice seeds did not inhibit seed germination and was able to increase the number of tillers, but had not been able to affect the increase in plant height.

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" The stone fruits occupy an important place in the human diet due to their complex chemical composition such as sugars, free organic acids, pectic substances and vitamins. The main damage of economic importance to the stone fruit species is caused by the monilia disease caused by the fungus Monilia laxa (Aderhold et Ruhland). The disease can affect several host tissues these include blossom blight, shoot blight, fruit blight and brown fruit rot. The purpose of this research was to evaluate the attack produced by the pathogen on peach, apricot and plum from the first decade of May until the second decade of August in Experimental Field of Horticulture Faculty, USAMV Bucharest in 2019. Results showed that plums had the highest attack rate (14%) and the lowest was in apricots (0.8%). It should be noted that monilia disease is a major threat for stone fruit trees because of its aggressive manifestation on the fruit, especially in plums and peaches."

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Leaf blight in the seedlings and young trees of Dalbergia sissoo, an epidemic disease in nurseries and plantations, caused by Alternaria alternata is recorded from western Uttar Pradesh. The symptoms of leaf blight started from margins and progressively to the midrib and giving a brown and crispy appearance to the infected leaves. To find out effective chemical fungicide for disease management, eight fungicides viz. Indofil M-45 [Mancozeb] (0.2%), Chlorothalonil (0.2%), Cuman-L [Ziram] (0.2%), Ridomil [Metalaxyl] (0.2%), Indofil Z-78 [Zineb] (0.2%), Copper oxychloride (0.2%), Jkstein [Methyl Benzimidazole Carbonate] (0.1%) and Topsin M [Thiophanate Methyl] (0.1%) were sprayed on D. sissoo seedlings in nursery. The results indicated that all the fungicides significantly reduced the disease incidence as compared to control. However, Indofil M-45 treatment was found to be most effective which exhibited 80.87 per cent disease control over control experiment.

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Inflorescence blight is a major disease in mango production (2,3). During a disease survey of mango in Puerto Rico conducted from February to April in 2009, 20% of the inflorescences were affected with inflorescence blight showing rachis and flower necrosis. Symptoms were observed in 70% of samples at the Mango Germplasm Collection of the University of Puerto Rico's Experiment Station in Juana Diaz. Blighted inflorescence tissue (necrotic and the interface between necrotic and healthy tissue) from mango cultivars ‘Haden’ and ‘Irwin’ were disinfested with 70% ethanol, rinsed with sterile water and transferred to acidified potato dextrose agar (APDA). Isolations (40%) produced fungi in the Botryosphaeriaceae. Isolates 90LY, 94LY, and 89LY were purified and identified morphologically using taxonomic keys (1,4) and by DNA sequence analyses as Neofusicoccum mangiferae (Syd. & P. Syd.) Crous, Slippers & A.J.L. Phillips. On APDA, colonies were gray with aerial mycelia that turned dark gray with age. Pycnidia were globose to pyriform and dark brown to black. Conidia (n = 50) were hyaline, ovoid, one-celled, and averaged 13.2 × 6.3 μm in size. PCR amplifications of the internal transcribed spacer region of rDNA using ITS5-ITS4 primers, and fragments of both β-tubulin and translation elongation factor 1-alpha (EF1-α) genes using Bt2a-Bt2b and EF1728F-EF1986R primers, respectively, were sequenced and analyzed using BLASTn query. Accession numbers of gene sequences submitted to GenBank were KF479465 to 67 for ITS region; KF479468 to 70 for β-tubulin; and KF479471 to 73 for EF1-α. All sequences were 99 to 100% identical to reference isolate CMW7024 (4) of N. mangiferae (GenBank Accession Nos. AY615185, AY615172, and DQ093221). For each fungal isolate, pathogenicity tests were conducted on mango trees using six randomly selected, healthy mango inflorescences at full bloom using two trees per cultivar. Both needle-wounded and unwounded inflorescences were inoculated with 5-mm diameter mycelial disks from 8-day-old cultures grown on APDA. Inflorescences were incubated in clear plastic bags for 8 days under field conditions. Controls were treated with APDA disks only. Inflorescences on ‘Irwin’ turned brown with necrosis extending from the rachis to flowers. Mycelial growth and inflorescence blight was observed with lesions ranging from 2 to 5 cm in length. On ‘Haden,’ the rachis tissues turned brown and necrotic with lesions ranging from 1.5 to 2 cm long and without mycelial growth. N. mangiferae was re-isolated from all diseased inflorescences, and no symptoms developed on controls, which fulfilled Koch's postulates. The test was repeated once. N. mangiferae was associated with blossom blight in Australia and South Africa (2,3). This is the first report of N. mangiferae causing rachis necrosis and inflorescence blight on mango in Puerto Rico. N. mangiferae belongs to a complex of pathogens causing inflorescence blight and rachis necrosis and, therefore, effective management of this important disease complex must involve control of this pathogen. References: (1) P. W. Crous et al. Stud. Mycol. 55:235, 2006. (2) G. I. Johnson et al. Ann. Appl. Biol. 119:465, 1991. (3) J. H. Lonsdale and J. M. Kotzé. Acta Hortic. 341:345, 1993. (4) A. J. L. Phillips. Key to the various lineages in “Botryosphaeria” Version 01 2007. Last retrieved 5 February 2014 from http://www.crem.fct.unl.pt/botryosphaeria_site/key.htm .

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Cassava (Manihot esculenta Crantz) is one of the staple food crops grown in Kenya. Diseases remain one of the major constraints for cassava production. Apart from other major viral diseaes Cassava mosaic and Cassava brown streak, Cassava bacterial blight (CBB) caused by Xanthom*onas axonopodis pv manihotis and Xanthom*onas axonopodis pv cassavae are a major constraint in cassava production in Kenya. This study was done to identify the prevalence, distribution, and farmers' knowledge of cassava bacterial blight in the coastal region of Kenya. A survey was conducted involving 250 farmers who were randomly selected from two regions of Kilifi and Taita Taveta counties. Among the 250 farmers interviewed, 61.6 % identified cassava bacterial blight symptoms in their farms. The main varieties found growing in the region were Tajirika, Karembo, Kibandameno, and Shibe which were all confirmed by farmers as susceptible to cassava bacterial blight. During the survey, plant samples were randomly collected in the field. Out of the 70 samples collected, 40 of them were confirmed positive with X.pv manihotis and X.pv cassavae which cause cassava bacterial blight. The study concluded that there is a widespread of cassava bacterial blight in Kilifi and Taita taveta counties. Kilifi County had the highest incidence of 22% with Taita Taveta having the lowest incidence of 13%. Kilifi County had a higher severity of 8% as compared to Taita Taveta which had 5% Severity. Therefore there is a need for a proper management program to be deployed in managing the disease to enhance cassava production in the region.

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Bacterial diseases, common blight, halo blight, brown spot, and wilt are major constraints to the production of dry edible beans in western Nebraska. Owing to a lack of effective control options, these diseases have been difficult to properly manage. Cultivars with partial disease resistance are available for some diseases, but not for all. Furthermore, few chemical products are accessible other than copper-based products, which have proven to be erratic in efficacy, depending on variables such as pathogen involved, disease pressure, and environmental conditions. Therefore, field studies were conducted in western Nebraska for 7 years (13 site years) evaluating newly emerging copper-alternative chemicals for managing these diseases in dry beans. Over this time period, five different products were tested for at least 2 years each and were compared with two commercially available copper compounds (Kocide and MasterCop). The new alternatives included two growth-promoting chemicals (ecoAgra A300, WakeUP Summer), and three contact sanitizers (Goldshield 5, SaniDate, and OxiDate). Treatments with SaniDate and ecoAgra A300 more consistently produced higher yields than other treatments, while not reducing disease incidence. These improvements were achieved primarily under high levels of disease, providing promise for use in production systems in western Nebraska.

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Leaf diseases on tea plants affect the quality of tea. This issue must be overcome since preparing tea drinks requires high-quality tea leaves. Various automatic models for identifying disease in tea leaves have been developed; however, their performance is typically low since the extracted features are not selective enough. This work presents a classification model for tea leaf disease that distinguishes six leaf classes: algal spot, brown, blight, grey blight, helopeltis, red spot, and healthy. Deep learning using a convolutional neural network (CNN) builds an effective model for detecting tea leaf illness. The Kaggle public dataset contains 5,980 tea leaf images on a white background. Pre-processing was performed to reduce computing time, which involved shrinking and normalizing the image prior to augmentation. Augmentation techniques included rotation, shear, flip horizontal, and flip vertical. The CNN model was used to classify tea leaf disease using the MobileNetV2 backbone, Adam optimizer, and rectified linear unit (ReLU) activation function with 224×224 input data. The proposed model attained the highest performance, as evidenced by the accuracy value 0.9455.

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Areca palm (Chrysalidocarpus lutescens) is a popular ornamental palm that can be grown outdoors in mild climates and is commonly used as an indoor ornamental plant. During 2005, commercial palm producers lost significant numbers of areca palm seedlings grown in transplant trays to a crown rot disease. Initial symptoms consisted of a light brown discoloration of stems near the soil line. As disease progressed, the brown discoloration extended up the stem and down into the crown, foliage became gray green, and the entire plant then dried up and died. Extensive, white, cottony mycelium and numerous sclerotia developed externally on the lower stem, crown, attached palm seed, and surrounding peat moss medium. Mycelial growth was so extensive that the fungus often grew from one transplant tray cell, bridged across the plastic cell border, and into an adjacent transplant cell. Tan, spherical sclerotia measured approximately 1 mm in diameter. Isolations from diseased plants resulted in the recovery of the same white fungus that produced sclerotia. On the basis of sclerotia morphology and the presence of clamp connections at hyphal septa, the fungus was identified as Sclerotium rolfsii. Pathogenicity was tested by growing isolates on potato dextrose agar, drying the resulting sclerotia for 48 h, and then depositing 8 to 10 sclerotia at the base of healthy areca palm seedlings. Five isolates were tested using 40 plants per isolate. Non-inoculated controls were also included. All plants were incubated in a greenhouse at 22 to 25°C. After 2 weeks, inoculated plants began to show brown necrosis at the base of the stems; by the third week, plants began to dry up, and mycelium and sclerotia developed on the crowns. S. rolfsii was reisolated from all necrotic crown and stem tissues. Noninoculated controls did not develop any disease symptoms. To my knowledge, this is the first report of southern blight of C. lutescens in California. This disease has been reported on areca palms and other foliage plants in the southern United States and Central and South America (1). Circ*mstantial evidence (the disease occurred on palm seedlings that were planted in previously unused transplant trays and new peat moss rooting medium) suggests that the pathogen may have been brought in on palm seed. In the nursery, other foliage plants that are susceptible to S. rolfsii were planted in the same rooting medium but were unaffected by southern blight. Reference: (1) A. R. Chase. Compendium of Ornamental Foliage Plant Diseases. The American Phytopathological Society. St. Paul, MN, 1987.

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Leaf blight is commonly observed in rubber trees (Hevea brasiliensis) and can be caused by several fungal species. From October to December 2021, the emergence rubber tree disease was observed in Krabi province, southern Thailand. Small brown to dark brown spots developed on the leaves of rubber trees and later expanded into most parts of the leaves. Fungal isolates were isolated from infected tissues and a total of 15 Calonectria-like isolates were recovered from 10 infected leaf samples. Pathogenicity testing using the agar plug method revealed that four isolates caused leaf blight on rubber tree, similar to the situation in natural infections. Based on morphological study and the molecular properties of internal transcribed spacer (ITS), calmodulin (cal), translation elongation factor 1-α (tef1-α), and β-tubulin 2 (tub2) sequences, the four fungal isolates were identified as Calonectria foliicola. To the best of our knowledge, this is the first report of rubber trees pas a new host for C. foliicola in Thailand and elsewhere. This study reports on an emerging disease affecting rubber trees in Thailand, and the results are of benefit for the development of an appropriate method to manage this emerging disease in Thailand.

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Rice is responsible for the stable crop of 3 billion people worldwide, about half of Asian depends on it, and rice is grown in more than 100 countries. Rice diseases can lead to devastating economic loss by decreasing yield production, disturbing a stable food supply and demand chain. The most commonly used method to control rice disease is chemical control. However, misuse of chemical control can cause environmental pollution, residual toxicity, and the emergence of chemical-resistant pathogens, the deterioration of soil quality, and the destruction of biodiversity. In order to control rice diseases, research on alternative biocontrol is actively pursued including microorganism-oriented biocontrol agents. Microbial agents control plant disease through competition with and antibiotic effects and parasitism against plant pathogens. Microorganisms isolated from the rice rhizosphere are studied comprehensively as biocontrol agents against rice pathogens. Bacillus sp., Pseudomonas sp., and Trichoderma sp. were reported to control rice diseases, such as blast, sheath blight, bacterial leaf blight, brown spot, and bakanae diseases. Here we reviewed the microorganisms that are studied as biocontrol agents against rice diseases.

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During recent growing seasons, a new leaf blight was observed on potatoes (Solanum tuberosum L.) in various production regions in South Africa. Symptoms were observed before early blight, from 50 to 60 days after emergence of the potato plants. Typical leaf symptoms were small, circular, brown lesions, first visible on the abaxial sides of leaves. Lesions resembled those of early blight, but were smaller and did not show concentric rings. During favorable environmental conditions, severe infections were seen as coalesced lesions and blighted leaves and stems. Such severe infections occurred in seasons when high humidity, leaf wetness, and warm temperatures were present. Yield losses as much as 40% were reported on approximately 50 20-ha pivots in various potato-growing regions, particularly Ceres, Eastern Free State, KwaZulu Natal, and Mpumalanga, due to this leaf blight because conventional fungicidal spray programs did not adequately control the disease. Isolations from leaf lesions were made on V8 juice agar under aseptic conditions. The fungus, Alternaria alternata (Fr.) Kreissler, was consistently isolated and preliminarily identified on the basis of morphological characteristics. Dark brown conidia were produced in chains on conidiophores. Conidia had short beaks and ranged from 20 to 60 × 9 to 18 μm. Morphological identification was confirmed by amplification of the internal transcribed spacer (ITS) region. Primers used were AAF2 (5′-TGCAATCAGCGTCAGTAACAAAT-3′) and AAR3 (5′-ATGGATGCTAGACCTTTGCTGAT-3′), specifically designed for identification of A. alternata (4). PCR products were sequenced and the identity of isolates confirmed by a BLAST search on the GenBank database. Koch's postulates were conducted by inoculation of healthy potato leaves of cv. BP1. Spores at a concentration of 106 spores per ml were suspended in an oil/surfactant mixture and sprayed onto leaves until runoff. Control plants were sprayed with a sterile oil/surfactant mixture until runoff. Plants were covered by polyethylene bags for 2 days to achieve high humidity levels and maintained in a greenhouse at 25 ± 2°C. Three days after inoculation, plants were exposed to a moisture regimen simulating that of in-field irrigation. Plants were placed in a fogging chamber twice a week for 1 h at a time. Leaf blight symptoms similar to those observed on diseased potato plants in the field began to develop 3 weeks after inoculation. Isolations made from these lesions consistently yielded A. alternata. Control plants did not develop any symptoms. Five plants were used for each treatment and the experiment was repeated twice. Leaf blight on potatoes caused by A. alternata has previously been reported in Israel, (2), Brazil (1), and North America (3). To our knowledge, this is the first report of A. alternata causing leaf blight on potatoes in South Africa. Future research will focus primarily on management of this disease. References: (1) L. S. Boiteux and F. J. B. Reifschneider. Plant Dis. 78:101. 1994. (2) S. Droby et al. Phytopathology 74:537, 1984. (3) W. W. Kirk et al. Plant Dis. Manage. Rep. 2:V065:1, 2007. (4) P. Konstantinova et al. Mycol. Res. 106:23, 2002.

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In Nepal, maize ranks second after rice both in area and production. In recent years, maize area and production has shown a steady increase, but productivity has been low (2.46 t/ha). The major maize producing regions in Nepal are mid hill (72.85%), terai (17.36%) and high hill (9.79%) respectively. A literature review was carried out to explore major maize diseases and their management in Nepal. The omnipresent incidence of diseases at the pre harvest stage has been an important bottleneck in increasing production. Till now, a total of 78 (75 fungal and 3 bacterial) species are pathogenic to maize crop in Nepal. The major and economically important maize diseases reported are Gray leaf spot, Northern leaf blight, Southern leaf Blight, Banded leaf and sheath blight, Ear rot, Stalk rot, Head smut, Common rust, Downy mildew and Brown spot. Information on bacterial and virus diseases, nematodes and yield loss assessment is also given. Description of the major maize diseases, their causal organisms, distribution, time and intensity of disease incidence, symptoms, survival, spreads, environmental factors for disease development, yield losses and various disease management strategies corresponded to important maize diseases of Nepal are gathered and compiled thoroughly from the available publications. Concerted efforts of NARC commodity programs, divisions, ARS and RARS involving research on maize pathology and their important outcomes are mentioned. The use of disease management methods focused on host resistance has also been highlighted.Journal of Maize Research and Development (2015) 1(1):28-52DOI: http://dx.doi.org/10.5281/zenodo.34292