A leaf spot is a limited, discoloured, diseased area of a leaf that is caused by fungal, bacterial or viral plant diseases, or by injuries from nematodes, insects, environmental factors, toxicity or herbicides. These discoloured spots or lesions often have a centre of necrosis. Symptoms can overlap across causal agents, however differing signs and symptoms of certain pathogens can lead to the diagnosis of the type of leaf spot disease. Prolonged wet and humid conditions promote leaf spot disease and most pathogens are spread by wind, splashing rain or irrigation that carry the disease to other leaves.
Phomopsis cane and leaf spot occurs wherever grapes are grown. Phomopsis cane and leaf spot is more severe in grape-growing regions characterized by a humid temperate climate through the growing season. Crop losses up to 30% have been reported to be caused by Phomopsis cane and leaf spot.
Alternaria is a genus of Deuteromycetes fungi. All species are known as major plant pathogens. They are also common allergens in humans, growing indoors and causing hay fever or hypersensitivity reactions that sometimes lead to asthma. They are present in the human mycobiome and readily cause opportunistic infections in immunocompromised people such as AIDS patients.
Alternaria brassicae is a plant pathogen able to infect most Brassica species including important crops such as broccoli, cabbage and oil seed rape. It causes damping off if infection occurs in younger plants and less severe leaf spot symptoms on infections of older plants.
Pyrenophora tritici-repentis (teleomorph) and Drechslera tritici-repentis (anamorph) is a necrotrophic plant pathogen of fungal origin, phylum Ascomycota. The pathogen causes a disease originally named yellow spot but now commonly called tan spot, yellow leaf spot, yellow leaf blotch or helminthosporiosis. At least eight races of the pathogen are known to occur based on their virulence on a wheat differential set.
Botryosphaeria ribis is a fungal plant pathogen that infects many trees causing cankers, dieback and death.
Phyllosticta cucurbitacearum, commonly called "Phyllosticta leaf spot", is a fungal plant pathogen affecting cucurbits.
Diplocarpon mespili is a pathogenic fungus which causes quince leaf blight, a leaf disease affecting chiefly common quince. It occurs in wet summers, causing severe leaf spotting and early defoliation, also affecting fruit to a lesser extent. It may also affect other Rosaceae such as hawthorn and medlar, but is typically less damaging than on quince.
Mycosphaerella henningsii is a fungal plant pathogen that causes Brown leaf spot (BLS) in cassava).Part
Pseudocercospora vitis is a fungal plant pathogen which causes isariopsis leaf spot,.
Septoria ampelina is a fungal plant pathogen that affects grapes causing septoria leaf spot.
Septoria cucurbitacearum is a fungal plant pathogen infecting cucurbits. Symptoms of Septoria leaf spot are similar on all the cucurbits infected.
Bipolaris incurvata is a plant pathogen that causes blight and leaf spots in coconut trees.
Stemphylium lycopersici is a plant pathogen infecting tomatoes, lettuce, Capsicum and papayas.
Isariopsis clavispora is a fungal plant pathogen that causes leaf spot on grape.
Septoria glycines is a fungal plant pathogen that causes leaf spot on soybean, a disease that is also known as brown spot. The disease leads to early defoliation of the plant, but does not normally cause severe reductions in yield. The fungus overwinters on infected soybean straw and is spread by wind dispersal or rain splash.
Gnomonia fructicola is a fungal plant pathogen on strawberries causing leaf spot disease. It can overwinter on leaves and fruits of Fragaria spp. (Rosaceae), occasionally pathogenic on fruits causing strawberry stem-end rot. The causal organism has often been referred to as Gnomoniacomari, now considered Gnomoniopsiscomari. It occurs in Canada, Europe and U.S.A..
Ophiognomonia is a genus of fungi in the family Gnomoniaceae.
Peyronellaea curtisii is a fungal plant pathogen first described by Miles Joseph Berkeley and received its current name in 2010. Formerly it was Stagonosporacurtisii. It is a cause of leaf blotch, and its substrates include Narcissus, Galanthus and Hippeastrum.
Gray leaf spot (GLS) is a foliar fungal disease that affects grasses. In grasses other than maize it is caused by Pyricularia grisea, which only infects perennial ryegrass, tall fescue, and St. Augustine grass in places with warm and rainy climates.
