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L. L. Wilson - One of the best experts on this subject based on the ideXlab platform.
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Effects of a Cover Crop on Splash Dispersal of Colletotrichum acutatum Conidia.
Phytopathology, 1998Co-Authors: N. Ntahimpera, L. L. Wilson, Michael A. Ellis, Laurence V. MaddenAbstract:ABSTRACT A rain simulator, with generated rains of 11 and 30 mm/h, was used to determine the effect of a cover crop or intercrop on the splash dispersal of Colletotrichum acutatum conidia. Dispersal through sudangrass, which can be used as a ‘living mulch’, was tested at two planting densities (140 or 280 kg/ha) and two heights (5 and 20 cm) and compared with a control consisting of a bare soil. Dispersal of C. acutatum conidia was assessed by counting colonies formed from spore-bearing splash droplets deposited in sheltered petri plates containing a selective medium. Both a cover crop and rain intensity significantly affected splash dispersal as measured by the interpolated total number of colonies (denoted by Σ) from 0 to 72 cm from the inoculum source and in a time span of 61 min of generated rain (P 0.90). Dispersal with a 30-mm/h rain was higher than dispersal with a 11-mm/h rain, and presence of a cover crop sig...
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Effect of Rain Distribution Alteration on Splash Dispersal of Colletotrichum acutatum.
Phytopathology, 1997Co-Authors: N. Ntahimpera, Laurence V. Madden, L. L. WilsonAbstract:ABSTRACT Splash dispersal of Colletotrichum acutatum conidia from infected strawberry fruit was assessed using a rain simulator to determine the properties of rain (e.g., intensity [millimeters/hour] or drop size distribution) most related to dissemination. Dispersal with a simulated rain corresponding to a natural rain of about 11 mm/h was compared with dispersal of three other simulated rains that had larger and smaller drop sizes, on average, than idealized natural rains. Splash droplets were collected in sheltered petri plates with a selective medium for Colletotrichum, and colonies formed from conidia entrained in the droplets were counted and used as the measure of dispersal. Colonies were mostly confined to a 27-cm radius from the source, and density of colonies decreased exponentially with the distance squared, as indicated by the fit of a diffusion-type model to the data. Splash dispersal was more affected by drop size distribution than rain intensity or other properties of the generated rains. T...
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Overwinter survival of Colletotrichum acutatum in infected strawberry fruit in Ohio
Plant Disease, 1992Co-Authors: L. L. Wilson, Laurence V. Madden, Michael A. EllisAbstract:Colletotrichum acutatum, a causal organism for anthracnose fruit rot of strawberry, was recovered from 100% of all infected strawberry fruit exposed for 18 wk in the laboratory to constant temperatures of -12 and -30 C or six cycles of fluctuating temperatures of -12 or -30 C for 2 wk followed by 5 C for 1 wk. In a 2-yr field study (1988-89, 1989-90), C. acutatum was recovered from nearly 100% of fruit located on the soil surface or 5-8 cm below the soil surface after exposure to winter conditions for 3 mo (November through January), but recovery of C. acutatum decreased with time after 3 mo (.)
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Splash dispersal of Colletotrichum acutatum and Phytophthora cactorum from strawberry fruit by single drop impactions
Phytopathology, 1992Co-Authors: Xiusheng Wang, L. L. Wilson, Laurence V. Madden, D. L. Reichard, Michael A. EllisAbstract:Dispersal of Colletotrichum acutatum conidia and Phytophthora cactorum sporangia by single drop impactions onto strawberry fruit was studied using a drop-generating system. Uniform water drops, 0.5-4 mm in diameter, were released from heights of 25-150 cm above infected target fruit with spores labeled with fluorescent tracer. Splash droplets were collected on water-sensitive paper. Size and distance from the source of each droplet trace were determined using an image analysis system, and number of spores contained in randomly chosen traces were counted by means of fluorescent microscopy (...)
Barbara J. Smith - One of the best experts on this subject based on the ideXlab platform.
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In vitro response of strawberry cultivars and regenerants to Colletotrichum acutatum
Plant Cell Tissue and Organ Culture, 2006Co-Authors: F.a. Hammerschlag, Sandra Garces, Margery Koch-dean, John Maas, Kim Lewers, Barbara J. SmithAbstract:Diseases affecting strawberry ( Fragaria × ananassa Duch.) have been of major concern in recent years because of their widespread occurrence and potential for yield loss. Anthracnose, caused by the fungus Colletotrichum acutatum , is one of the most serious diseases of strawberry worldwide. Tissue-culture induced (somaclonal) variation provides one strategy for generating disease-resistant genotypes. As part of a program to generate strawberry germplasm resistant to anthracnose, an in vitro screening system was used to evaluate several commercial cultivars, Chandler, Delmarvel, Honeoye, Latestar, Pelican and Sweet Charlie propagated in vitro , and shoots regenerated from leaf explants of these cultivars for resistance to C.␣acutatum isolate Goff (highly virulent). Regenerants with increased levels of resistance were identified from all of the cultivars. The greatest increases in disease resistance were observed for regenerants from leaf explants of cultivars Pelican and Chandler that exhibited 17.5- and 6.2-fold increases in resistance, respectively. The highest levels of anthracnose resistance (2 to 6% leaf necrosis) were exhibited by regenerants from explants of cultivars Pelican and Sweet Charlie. These studies suggest that generating somaclonal variation may be a viable approach to obtaining strawberry plants with increased levels of anthracnose resistance.
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Strawberry Anthracnose: Histopathology of Colletotrichum acutatum and C. fragariae.
Phytopathology, 2002Co-Authors: Kenneth J. Curry, Maritza Abril, Jana B. Avant, Barbara J. SmithAbstract:Curry, K. J., Abril, M., Avant, J. B., and Smith, B. J. 2002. Strawberry anthracnose: Histopathology of Colletotrichum acutatum and C. fragariae. Phytopathology 92:1055-1063. Ontogeny of the invasion process by Colletotrichum acutatum and C. fragariae was studied on petioles and stolons of the strawberry cultivar Chandler using light and electron microscopy. The invasion of host tissue by each fungal species was similar; however, each invasion event occurred more rapidly with C. fragariae than with C. acutatum. Following cuticular penetration via an appressorium, subsequent steps of invasion involved hyphal growth within the cuticle and within the cell walls of epidermal, subepidermal, and subtending cells. Both species of fungi began invasion with a brief biotrophic phase before entering an extended necrotrophic phase. Acervuli formed once the cortical tissue had been moderately disrupted and began with the development of a stroma just beneath the outer periclinal epidermal walls. Acervuli erupted through the cuticle and released conidia. Invasion of the vascular tissue typically occurred after acervulus maturation and remained minimal. Chitin distribution in walls of C. fragariae was visualized with gold-labeled wheat germ agglutinin. The outer layer of bilayered walls of conidia, germ tubes, and appressoria contained less chitin than unilayered hyphae in planta. Additional keywords: colloidal gold, hemibiotrophy, host–pathogen interactions, lectin, ultrastructure.
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308 Screening Strawberry in Vitro for Response to Colletotrichum acutatum
HortScience, 2000Co-Authors: Sandra Garces, Barbara J. Smith, Margery Koch-dean, John Maas, F.a. HammerschlagAbstract:As part of a program to generate anthracnose (Colletotrichum acutatum) resistance in strawberry (Fragaria × ananassa Duch.) via either tissue culture or gene transfer techniques, studies were conducted to determine whether in vitro screening for resistance to C. acutatum was feasible. Six commercial cultivars (Latestar, Delmarvel, Pelican, Sweet Charlie, Chandler, and Honeoye) that differed in their response to the pathogen under field conditions were tested to see whether this response was reflected in vitro. Leaves from 4-week-old shoot cultures were soaked in a spore suspension of C. acutatum isolate Goff, transferred to 0.5% water agar, and the presence or absence of disease symptoms was evaluated on a 0-4 rating scale after 7 days. Five of the six cultivars exhibited a disease rating similar to field results. This study suggests that there is potential to use this procedure as a screening technique, and studies are in progress to screen strawberry regenerants for resistance.
Laurence V. Madden - One of the best experts on this subject based on the ideXlab platform.
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Effects of a Cover Crop on Splash Dispersal of Colletotrichum acutatum Conidia.
Phytopathology, 1998Co-Authors: N. Ntahimpera, L. L. Wilson, Michael A. Ellis, Laurence V. MaddenAbstract:ABSTRACT A rain simulator, with generated rains of 11 and 30 mm/h, was used to determine the effect of a cover crop or intercrop on the splash dispersal of Colletotrichum acutatum conidia. Dispersal through sudangrass, which can be used as a ‘living mulch’, was tested at two planting densities (140 or 280 kg/ha) and two heights (5 and 20 cm) and compared with a control consisting of a bare soil. Dispersal of C. acutatum conidia was assessed by counting colonies formed from spore-bearing splash droplets deposited in sheltered petri plates containing a selective medium. Both a cover crop and rain intensity significantly affected splash dispersal as measured by the interpolated total number of colonies (denoted by Σ) from 0 to 72 cm from the inoculum source and in a time span of 61 min of generated rain (P 0.90). Dispersal with a 30-mm/h rain was higher than dispersal with a 11-mm/h rain, and presence of a cover crop sig...
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Effect of Rain Distribution Alteration on Splash Dispersal of Colletotrichum acutatum.
Phytopathology, 1997Co-Authors: N. Ntahimpera, Laurence V. Madden, L. L. WilsonAbstract:ABSTRACT Splash dispersal of Colletotrichum acutatum conidia from infected strawberry fruit was assessed using a rain simulator to determine the properties of rain (e.g., intensity [millimeters/hour] or drop size distribution) most related to dissemination. Dispersal with a simulated rain corresponding to a natural rain of about 11 mm/h was compared with dispersal of three other simulated rains that had larger and smaller drop sizes, on average, than idealized natural rains. Splash droplets were collected in sheltered petri plates with a selective medium for Colletotrichum, and colonies formed from conidia entrained in the droplets were counted and used as the measure of dispersal. Colonies were mostly confined to a 27-cm radius from the source, and density of colonies decreased exponentially with the distance squared, as indicated by the fit of a diffusion-type model to the data. Splash dispersal was more affected by drop size distribution than rain intensity or other properties of the generated rains. T...
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Overwinter survival of Colletotrichum acutatum in infected strawberry fruit in Ohio
Plant Disease, 1992Co-Authors: L. L. Wilson, Laurence V. Madden, Michael A. EllisAbstract:Colletotrichum acutatum, a causal organism for anthracnose fruit rot of strawberry, was recovered from 100% of all infected strawberry fruit exposed for 18 wk in the laboratory to constant temperatures of -12 and -30 C or six cycles of fluctuating temperatures of -12 or -30 C for 2 wk followed by 5 C for 1 wk. In a 2-yr field study (1988-89, 1989-90), C. acutatum was recovered from nearly 100% of fruit located on the soil surface or 5-8 cm below the soil surface after exposure to winter conditions for 3 mo (November through January), but recovery of C. acutatum decreased with time after 3 mo (.)
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Splash dispersal of Colletotrichum acutatum and Phytophthora cactorum from strawberry fruit by single drop impactions
Phytopathology, 1992Co-Authors: Xiusheng Wang, L. L. Wilson, Laurence V. Madden, D. L. Reichard, Michael A. EllisAbstract:Dispersal of Colletotrichum acutatum conidia and Phytophthora cactorum sporangia by single drop impactions onto strawberry fruit was studied using a drop-generating system. Uniform water drops, 0.5-4 mm in diameter, were released from heights of 25-150 cm above infected target fruit with spores labeled with fluorescent tracer. Splash droplets were collected on water-sensitive paper. Size and distance from the source of each droplet trace were determined using an image analysis system, and number of spores contained in randomly chosen traces were counted by means of fluorescent microscopy (...)
Arne Stensvand - One of the best experts on this subject based on the ideXlab platform.
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Colletotrichum acutatum occurs asymptomatically on apple leaves
European Journal of Plant Pathology, 2016Co-Authors: Jorunn Børve, Arne StensvandAbstract:Fungi within the Colletotrichum acutatum species complex occur asymptomatically on plant parts of many different plant species. Leaves from apple orchards in southern Norway were sampled, frozen for five hours and incubated for six days to reveal presence of asymptomatic infections of C. acutatum. Number of leaves (incidence) and leaf area covered (severity) with conidial masses of C. acutatum were assessed biweekly on cv. Aroma from late May to late September during three growing seasons. The first finding of conidial masses occurred in the second half of July, and there was a higher incidence occurring in August and September. Sampling of leaves from fruit spurs and vegetative shoots of cvs. Aroma and Elstar showed that conidial masses of C. acutatum developed on leaves on both shoot types, and there was no difference in incidence between these two types. The fungus was detected on leaves from six of eight commercial orchards of cv. Aroma over three years, with a mean incidence of 5.5 %. After storage, bitter rot was found on apple fruit from all eight orchards. There was no correlation between incidence of conidial masses of C. acutatum on leaves and on fruit. In all orchards and seasons investigated, incidence and severity on leaves varied from 0 to 67 % and 0 to 85 %, respectively. The discovery of apple leaves containing conidial masses of C. acutatum clearly indicate for leaves as a potential source of inoculum for fruit infections.
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Yellow Dryad, a New Host Plant of Colletotrichum acutatum in Switzerland
Plant disease, 2011Co-Authors: V. V. Michel, Arne Stensvand, G. M. StrømengAbstract:In spring 2008, yellow dryad (Dryas drummondii L.), an ornamental plant, was studied at the Research Center Conthey (Switzerland) for its possible use by the cosmetical industry. Plants grown from wild-type seeds were multiplied by transplanting cuttings in pots that were later transplanted in an experimental field plot. Before field planting, partial wilting occurred on several plants. The petioles of affected leaves appeared dry, tan, and covered with black acervuli containing black setae. Isolation from the acervuli on potato dextrose agar (PDA) containing chlortetracycline (25 mg/liter) resulted in the growth of white-to-gray mycelium containing salmon-colored conidial masses but no setae. The underside of the colony was carmine red. Conidia were primarily fusiform with an average size of 13 × 4 μm. On the basis of these morphological traits, the pathogen was identified as Colletotrichum acutatum J.H. Simmonds (2). PCR using the species-specific primer CaInt2 in conjunction with the conserved primer I...
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Colletotrichum acutatum occurs asymptomatically on sweet cherry leaves
European Journal of Plant Pathology, 2010Co-Authors: Jorunn Børve, Rolf Tore Djønne, Arne StensvandAbstract:Leaves of sweet cherry, exposed to either paraquat or freezing to quickly senesce the leaf tissue, were incubated in about 100% RH at 25°C for 6 d. Sporulating colonies of Colletotrichum acutatum , the cause of anthracnose, developed on up to 100% of the paraquat-treated and frozen leaves, and on none of the untreated controls. Number of leaves and leaf area containing C. acutatum on naturally infected leaves increased over time from May to September. Mean incidence of C. acutatum on leaf blades on fruit spurs and vegetative shoots from eight orchard/year samplings were 41 and 33%, respectively. Secondary conidiation (formation of short hyphae and new conidia) from conidia applied to detached leaves took place 6 h after inoculation, but only up to 3% of the conidia formed new conidia. It may be concluded that asymptomatic sweet cherry leaves frequently host C. acutatum and may be a potential inoculum source for cherry fruit.
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Colletotrichum acutatum Found on Apple Buds in Norway
Plant Health Progress, 2007Co-Authors: Jorunn Børve, Arne StensvandAbstract:Healthy appearing buds of five apple cultivars from 2 experimental and 9 commercial orchards were collected and incubated in saturated air at 20°C in early spring (prior to bud break) over three years. Colletotrichum acutatum sporulated on 0 to 7% (mean 1.3%) of the buds from both commercial and experimental orchards. Infected apple buds are suggested as a potential source of inoculum in spring. Accepted for publication 5 February 2007. Published 22 May 2007.
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Colletotrichum acutatum Overwinters on Sweet Cherry Buds
Plant disease, 2006Co-Authors: Jorunn Børve, Arne StensvandAbstract:Either naturally infected or artificially inoculated sweet cherry (Prunus avium) buds on fruit spurs (mainly containing generative buds) and on 1-year-old shoots (mainly containing vegetative buds) were examined for presence of Colletotrichum acutatum prior to the beginning of spring growth in each of 4 years. Artificial inoculations were made during the growing seasons preceding the bud sampling. The plant material was incubated moist for either 14 (fruit spurs) or 21 (1-year-old shoots) days at 20°C. Following moist incubation at 20°C, C. acutatum frequently sporulated on buds of fruit spurs and shoots. The fungus sporulated in orange, short-thread or hornlike structures, mainly on distal parts of the buds, and was usually easily visible with the unaided eye. The incidence of infected buds on naturally infected and inoculated fruit spurs was 2 to 80% and 38 to 79%, respectively. Incidence on naturally infected and inoculated shoots was 0 to 53% and 4 to 45%, respectively. On buds within fruit spurs, the incidence of C. acutatum was significantly higher on generative than on vegetative buds. This investigation shows that buds can host C. acutatum and thus are likely to be an important source of primary inoculum for anthracnose of sweet cherry.
Michael A. Ellis - One of the best experts on this subject based on the ideXlab platform.
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Effects of a Cover Crop on Splash Dispersal of Colletotrichum acutatum Conidia.
Phytopathology, 1998Co-Authors: N. Ntahimpera, L. L. Wilson, Michael A. Ellis, Laurence V. MaddenAbstract:ABSTRACT A rain simulator, with generated rains of 11 and 30 mm/h, was used to determine the effect of a cover crop or intercrop on the splash dispersal of Colletotrichum acutatum conidia. Dispersal through sudangrass, which can be used as a ‘living mulch’, was tested at two planting densities (140 or 280 kg/ha) and two heights (5 and 20 cm) and compared with a control consisting of a bare soil. Dispersal of C. acutatum conidia was assessed by counting colonies formed from spore-bearing splash droplets deposited in sheltered petri plates containing a selective medium. Both a cover crop and rain intensity significantly affected splash dispersal as measured by the interpolated total number of colonies (denoted by Σ) from 0 to 72 cm from the inoculum source and in a time span of 61 min of generated rain (P 0.90). Dispersal with a 30-mm/h rain was higher than dispersal with a 11-mm/h rain, and presence of a cover crop sig...
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Overwinter survival of Colletotrichum acutatum in infected strawberry fruit in Ohio
Plant Disease, 1992Co-Authors: L. L. Wilson, Laurence V. Madden, Michael A. EllisAbstract:Colletotrichum acutatum, a causal organism for anthracnose fruit rot of strawberry, was recovered from 100% of all infected strawberry fruit exposed for 18 wk in the laboratory to constant temperatures of -12 and -30 C or six cycles of fluctuating temperatures of -12 or -30 C for 2 wk followed by 5 C for 1 wk. In a 2-yr field study (1988-89, 1989-90), C. acutatum was recovered from nearly 100% of fruit located on the soil surface or 5-8 cm below the soil surface after exposure to winter conditions for 3 mo (November through January), but recovery of C. acutatum decreased with time after 3 mo (.)
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Splash dispersal of Colletotrichum acutatum and Phytophthora cactorum from strawberry fruit by single drop impactions
Phytopathology, 1992Co-Authors: Xiusheng Wang, L. L. Wilson, Laurence V. Madden, D. L. Reichard, Michael A. EllisAbstract:Dispersal of Colletotrichum acutatum conidia and Phytophthora cactorum sporangia by single drop impactions onto strawberry fruit was studied using a drop-generating system. Uniform water drops, 0.5-4 mm in diameter, were released from heights of 25-150 cm above infected target fruit with spores labeled with fluorescent tracer. Splash droplets were collected on water-sensitive paper. Size and distance from the source of each droplet trace were determined using an image analysis system, and number of spores contained in randomly chosen traces were counted by means of fluorescent microscopy (...)