The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform
M. A. Stoltz - One of the best experts on this subject based on the ideXlab platform.
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Physiologic Leaf Spot of winter wheat
Plant Disease, 1993Co-Authors: Richard W. Smiley, L.-m. Gillespie-sasse, W. Uddin, H. P. Collins, M. A. StoltzAbstract:A Leaf Spot of unknown etiology damages winter wheat in the northwestern United States. The symptoms are similar to Septoria Leaf blotch and tan Spot, but the causal agents of these diseases are not present. Leaf Spot symptoms are described. Dominant microbial colonists of the Spots were Cladosporium herbarum, C. macrocarpum, C. cladosporioides, and Alternaria species. Leaf Spot symptoms could not be induced on fresh Leaf tissues with any of the inoculation or incubation procedures examined (.)
Jared M. Leboldus - One of the best experts on this subject based on the ideXlab platform.
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The Correlation Between Septoria Leaf Spot and Stem Canker Resistance in Hybrid Poplar
Plant disease, 2016Co-Authors: Kelsey L. Dunnell, Jared M. LeboldusAbstract:Sphaerulina musiva is an important fungal pathogen that causes a Leaf Spot and stem canker disease of hybrid poplar. Stem cankers are widely regarded as the greatest threat to hybrid poplar plantations because of their ability to cause tree mortality; thus, the efforts of breeding programs have been focused on stem canker resistance. To explore the relationship between resistance to Leaf Spot and stem canker in Populus nigra × P. deltoides hybrids, two experiments were conducted. Initially, comparisons among leaves of different ages indicated that younger leaves were more susceptible to Leaf Spot infection than older leaves. Correlations between Leaf Spot severity and stem canker severity for both individual leaves and all leaves averaged together indicated that, in 10 of 11 comparisons, there were no significant correlations. The lack of correlation suggests that deploying genotypes resistant to stem canker may not affect the pathogen population causing Leaf Spot disease. To our knowledge, this is the first study specifically designed to test the correlation between stem canker resistance and Leaf Spot resistance by inoculating whole trees with a spore suspension in a controlled environment.
Richard W. Smiley - One of the best experts on this subject based on the ideXlab platform.
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Physiologic Leaf Spot of winter wheat
Plant Disease, 1993Co-Authors: Richard W. Smiley, L.-m. Gillespie-sasse, W. Uddin, H. P. Collins, M. A. StoltzAbstract:A Leaf Spot of unknown etiology damages winter wheat in the northwestern United States. The symptoms are similar to Septoria Leaf blotch and tan Spot, but the causal agents of these diseases are not present. Leaf Spot symptoms are described. Dominant microbial colonists of the Spots were Cladosporium herbarum, C. macrocarpum, C. cladosporioides, and Alternaria species. Leaf Spot symptoms could not be induced on fresh Leaf tissues with any of the inoculation or incubation procedures examined (.)
Soum Sanogo - One of the best experts on this subject based on the ideXlab platform.
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Etiology of Alternaria Leaf Spot of Cotton in Southern New Mexico.
Plant disease, 2019Co-Authors: Yi Zhu, Phillip Lujan, Srijana Dura, Robert L. Steiner, Jinfa Zhang, Soum SanogoAbstract:Alternaria Leaf Spot (caused by Alternaria spp.) is one of the most common foliar diseases of cotton (Gossypium spp.) and occurs in most cotton-growing regions of the world. In surveys of commercial cotton fields, Alternaria Leaf Spot has increased in prevalence and incidence in southern New Mexico due to favorable environmental conditions in recent years. Incidence, severity, and etiology of Leaf Spot of cotton in southern New Mexico were determined. Fourteen cotton fields with plants exhibiting Leaf Spot symptoms were evaluated in October and November 2016, when plants were at late growth stage. Disease incidence was 100% in 13 of the fields, and averaged 70% in the 14th field. Average disease severity index for all fields ranged from 21.5 to 87.0. For identification of the causal agent, 14 isolates (one from each field) were characterized based on morphological features and PCR using universal primers ITS4/ITS5 and primers targeting the plasma membrane ATPase gene. Colonies of all 14 isolates were olive green with distinct white margins and relatively small spores when compared with reference isolates of large-spored species. All 14 isolates were identified as A. alternata. The fungus grew on potato dextrose agar from 5 to 35°C, and optimum growth occurred at temperatures between 20 and 30°C. Cotton plants inoculated with selected isolates of A. alternata displayed symptoms similar to those observed under field conditions. This is the first report of A. alternata as a causal agent of Alternaria Leaf Spot on cotton in southern New Mexico.
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Outbreaks of Soybean Frogeye Leaf Spot in Iowa.
Plant disease, 2001Co-Authors: Xiao-bing Yang, M. D. Uphoff, Soum SanogoAbstract:Frogeye Leaf Spot of soybean, caused by Cercospora sojina, is typically a disease of warm and humid regions (2). Although the disease was reported in the Midwest in the 1920s (1), no outbreaks have been recorded in Iowa. Outbreaks of frogeye Leaf Spot occurred during 1999 in soybean fields in Ames and Grand Junction in central Iowa. During the 2000 growing season, the disease occurred in southwestern, southcentral, central, southeastern, and east-central Iowa. Occurrences of the disease with severity (reduction of green Leaf area) greater than 50% were observed in production soybean fields at Grand Junction in central Iowa and Central City in eastern Iowa. In a 12-ha no-till field planted with cv. Asgrow 2501, the disease was noticeable and uniformly distributed in the entire field in mid July. Disease severity in this field was greater than 70% by the end of August. Disease incidence, however, was less than 10% in three adjacent soybean fields. In a soybean performance test at a central Iowa location where the disease occurred in 1999 and 2000, the disease was observed on all 80 varieties, with four having a severity equal to or greater than 40%. Fourteen entries had less than a 10% disease severity and 19 entries had a disease severity equal to or greater than 30%. Infected leaves in these locations had typical lesions of frogeye Leaf Spot, which appeared as reddish brown margins surrounding light brown or ash gray centers. On the infected tissues, hyaline, straight, and multiseptate conidia from clustered conidiophores were found, isolated, and identified to C. sojina. The relatively warm winter temperatures in 1998 to 1999 and 1999 to 2000 were associated with frogeye Leaf Spot epidemics. Because of the seedborne nature of C. sojina, efforts are warranted to monitor and survey the occurrence of frogeye Leaf Spot in Iowa, an important seed production state in the northern soybean production region. References: (1) K. Athow and A. H. Probst. Phytopathology 42:660-662, 1952. (2) D. V. Phillips. 1999. Pages 20-21 in: Soybean Disease Compendium. Hartman et al. eds, American Phytopathological Society. St. Paul, MN.
Kelsey L. Dunnell - One of the best experts on this subject based on the ideXlab platform.
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The Correlation Between Septoria Leaf Spot and Stem Canker Resistance in Hybrid Poplar
Plant disease, 2016Co-Authors: Kelsey L. Dunnell, Jared M. LeboldusAbstract:Sphaerulina musiva is an important fungal pathogen that causes a Leaf Spot and stem canker disease of hybrid poplar. Stem cankers are widely regarded as the greatest threat to hybrid poplar plantations because of their ability to cause tree mortality; thus, the efforts of breeding programs have been focused on stem canker resistance. To explore the relationship between resistance to Leaf Spot and stem canker in Populus nigra × P. deltoides hybrids, two experiments were conducted. Initially, comparisons among leaves of different ages indicated that younger leaves were more susceptible to Leaf Spot infection than older leaves. Correlations between Leaf Spot severity and stem canker severity for both individual leaves and all leaves averaged together indicated that, in 10 of 11 comparisons, there were no significant correlations. The lack of correlation suggests that deploying genotypes resistant to stem canker may not affect the pathogen population causing Leaf Spot disease. To our knowledge, this is the first study specifically designed to test the correlation between stem canker resistance and Leaf Spot resistance by inoculating whole trees with a spore suspension in a controlled environment.
