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The black spots are circular with a perforated edge, and reach a diameter of 14 mm (1 ⁄ 2 inch). Badly affected plants, however, will not show the circular patterning, as they combine to cause a large, black mass. The common treatment of the disease is to remove the affected leaves and spray with antifungal solutions.
The disease is primarily caused by dermatophytes in the genera Trichophyton and Microsporum that invade the hair shaft. The clinical presentation is typically single or multiple patches of hair loss, sometimes with a 'black dot' pattern (often with broken-off hairs), that may be accompanied by inflammation, scaling, pustules, and itching.
[3] [6] They are everywhere and infection occurs after spores are either breathed in, come into contact with skin or enter the body through the skin such as via a cut, wound or injection. [3] Candida albicans is the most common cause of fungal infection in people, particularly as oral or vaginal thrush, often following taking antibiotics. [3]
Citrus Black Spot has a large economic impact on many countries because the black blemishes make it undesirable for human consumption and therefore the infected fruit cannot be sold. This type of economic impact is felt most in Australia and South Africa where the disease has been present for a number of years. [37]
The symptoms give the disease its name. The first signs of infection that can be seen are yellow and brown spots that develop on the living needles, [7] [8] which soon turn red. This infection starts on the base of the crown on older needles, which then turn a brownish red at the tip, while the rest of the needle remains green. [9]
Identification of Malassezia on skin has been aided by the application of molecular or DNA-based techniques. These investigations show that the M. globosa is the species that causes most skin disease in humans, and that it is the most common cause of dandruff and seborrhoeic dermatitis (though M. restricta is also involved). [6]
White mycelia growth on lesions that appear several days after infection is a sign of the causal pathogen of black pod disease, which is Phytophthora spp. Black pod disease starts when the infected pod shows some little yellow spots, which eventually turn brown and enlarge to a dark brown or black lesion within five days.
C. coccodes can cause lesions, twisted leaves, and a bleached color on onion. [4] On tomato, can see that there are sunken in dark spots. As the disease continues to develop can begin to see spots that are rotting. The pathogen can infect both green and ripe fruit; spots are not evident on green right away, but over time they develop. [5]