Cercospora leaf spot General information Cercospora leaf spot is a common disease in beetroot and silver beet but is usually unimportant in well-managed crops. It may be a significant problem in crops grown for baby-leaf production, because the foliage is the saleable product. Cause The fungi Cercospora beticola, C. Cercospora spot in avocado is caused by the fungus Pseudocercospora purpurea. This tissue becomes thin and brittle, and often drops out, leaving a ragged hole. In capsicums small, round water-soaked lesions develop on leaves, petioles and stems.
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In Spanish the diseases are called mancha ocular del cafeto and mancha de hierro. Host plant Coffea arabica L. Arabica coffee is among about 40 Coffea species in the family Rubiaceae that can be affected by this disease. Its shiny, oval, pointed leaves are 3—6 inches long. Its flowers are white, fragrant, and massed in thick clusters at leaf axils along the wide-spreading branches. The genus originates from the Old World tropics, especially Africa.
Pathogen The fungus Cercospora coffeicola Berk. The conidial scars are distinct and thickened. Pathogen dispersal is by spores conidia that are windborne mostly during the daytime and may also be spread by splashing rain and human contact such as movement of workers and by machinery within coffee fields and nurseries. Department of Agriculture. Andrew G. Lesions begin as small, chlorotic spots that expand to become deep brown on the upper leaf surface.
The centers of the spots turn grayish-white and are encircled by a distinct ring 0. The margins of the lesions are dark brown to reddish brown or purplish to black in color. Dark-colored and silvery-colored sporulation of the pathogen may be visible to the naked eye within the grayish-white centers of lesions. Affected leaves may defoliate prematurely. Lesions on berries are initially brown in color, sunken, longitudinal or irregular or oval in shape, with ashy centers, rarely 0.
Infections can occur at any stage of berry development. Red cherries Premature ripening of diseased cherries, a symptom and a damaging effect of Cercospora berry blotch disease.
Prematurely ripened fruits usually are not picked on time and therefore constitute crop loss. Large, sunken, blackened areas develop, which may be covered with a silvery sheen of fungal spores. Infections that penetrate to the seed may cause the pulp to adhere to the parchment during processing, causing damage to the product.
Diseased cherries may be subject to attack and further degradation by opportunistic bacteria or fungi such as Colletotrichum gloeosporioides a ubiquitous fungus that causes anthracnose of many crops. The conspicuous presence of C. Damage to cherries and seeds beans , when the disease is severe, leads to general crop loss yield reduction, berry shriveling, premature berry drop, premature ripening, and reduced coffee grade.
Coffee beans may be stained or 2 Cercospora berry blotch on mature coffee berries. Berry infections typically begin at the blossom end of fruits where there is a small, circular receptacle which holds water after dew or rainfall , and progresses basipetally along the longitudinal axis of the fruit, toward the peduncle. In fact, the disease may be effectively prevented or controlled in most locations with a proper fertility regime.
The pruned plant exhibiting nutrient deficiency symptoms foreground has Cercospora leaf spots, whereas the normal plant background is free of Cercospora leaf spots, illustrating that adequate coffee plant nutrition is a key to preventing this disease note: the yellowing of the plant in the foreground could be caused by a number of factors.
Provide or ensure adequate soil drainage this minimizes root rot. Avoid over-irrigation this will minimize plant stresses such as root rot and will reduce relative humidity within the plant canopy. Avoid working with coffee plants and moving through fields and nurseries when diseased plants are wet this minimizes potential dispersal of fungal conidia within and among moist plants.
Prune coffee trees to increase air circulation in the canopy. Harvest cherries on time, before disease progresses too far. Control weeds this minimizes plant stress and relative humidity in the plant canopy.
Apply fungicide sprays to foliage where environmental conditions are particularly conducive to infection and disease development please refer to Fungicide Recommendations below. Avoid planting coffee transplants too deep in soils. Protect new coffee foliage re-growth with fungicide sprays after pruning immature leaves are more susceptible to infection than mature leaves. It is important to protect the fruits from the leaf phase of the disease. For Kocide products, use from 1. Sprays should coincide with dry weather and calm winds.
Three spray applications per season should suffice occurring approximately once per month , beginning at flowering. Thorough coverage of the plant canopy is very important. Always refer to the fungicide label s for instructions and personal protective equipment and proper site of application for example, copper fungicides should be applied to leaves, and not to roots. Be aware that use of copper fungicides may eliminate fungi that perform biological control of the green scale Coccus viridis insect pest of coffee.
Premature ripening of infected berries and cherries occurs due to ethylene gas emission during the disease process.
Ethylene is a plant-ripening, or senescence, hormone that is also produced by some plant-pathogenic fungi during infection and disease development. References American Phytopathological Society list of coffee diseases J. Bittenbender, H. Growing coffee in Hawaii. Mulder, J. Cercospora coffeicola. IMI descriptions of fungi and bacteria, no. Crop protection compendium. Daub, M. Annual Review of Phytopathology — Arabica coffee manual. Liberato, J.
Brown eye spot of coffee Cercospora coffeicola pest and diseases image library. Nelson, S. Coffee pest and disease image gallery. Smith, V. Hawaii Coffee Quarterly, issue no. Staver, C. Guharay, D. Monterroso, and R. Designing pest-suppressive multistrata perennial crop systems: Shade-grown coffee in Central America. Agroforestry Systems —
These are often called the coffee "cherries". Each fruit contains 2 seeds i. These differing symptoms help explain the various common names for the disease: Cercospora "Leaf Spot" and Cercospora "Berry Blotch" Cercospora is reference to the deuteromycete stage. This halo is caused by the toxin cercosporin , produced by Cercospora species. In general, lesions of this species are able to fuse, and can form large irregular areas of necrotic tissue.
Cercospora Leaf Spot and Berry Blotch of Coffee
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