disease due to kingdom Fungi in the genus Calonectria present a pregnant menace to the ornamental horticulture industriousness in Europe and the United States . Calonectria spp . are in particular intriguing pathogens to manage in ornamental production systems and the urban landscape for multiple reasons . A high spirit level of mintage diversity and badly resolved taxonomy in the genus makes right pathogen identification and disease diagnosis .
presently , Calonectria spp . are causal agents of of import diseases in tropical and subtropic climates around the populace . They are polyphagous and nonhost - specific fungi . In Australia , South America , South Africa , and Asia , these diseases cause extensive deprivation in forestry Plantation . In the United States and Europe , these pathogen are responsible for many diseases on a wide chain of mountains of cosmetic plants . Impact of Calonectria Diseases . Symptoms let in leafage spot ; crown , pinch , and tooth root rot ; stem lesions ; and shoot blight . As a upshot of these contagion , plants can show wilting , stunting , greensickness , or defoliation .
Disease symptoms triggered by Calonectria
In ornamental nurseries , infections start at former stage of seedling and write out extension in the greenhouse ( Fig . 3A ) , lead to severe economic personnel casualty . well up and cracking of necrotic orbit at crown or basal root level may develop into basal radical canker . Leaf dapple symptoms triggered by Calonectria spp . alter concord to emcee species , master of ceremonies age , and pathogen species . Generally , they lie in of small , water - soaked spots that are chocolate-brown , carmine , or purple in semblance , which finally turn light to dismal browned with years and are fence by a red , brown , or purple perimeter and greensick annulus . symptom of folio patch often start at the leafage lead and , under conductive conditions , the entire leaves become brown or blackened . Moreover , characteristic black , elongated streak or cankers can begin to appear along the bloc of the shoot following contagion within a single season .
The enceinte number of describe specie observed in the genus Calonectria and the emersion of novel pathogen species such as the causal agent of Turkish boxwood blight suggest that Calonectria disease will persist in to be a challenge for ornamental horticulture industries in Europe and the United States .
enquiry continue to address significant questions about the biology and management of Calonectria spp . as pathogens of ornamental plants . Resistant commercial cultivars are needed for long - term sustainable management of Calonectria diseases on cosmetic plants . Further evaluation and integration of disease - insubordinate cultivars with integrated chemical , biological , and cultural controls will provide extra options for the direction of Calonectria disease on decorative plants in nursery production system and the landscape .
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