Mildew is a form of fungus. It is distinguished from its closely related counterpart, mold, largely by its colour: molds appear in shades of black, blue, red, and green, whereas mildew is white. It appears as a thin, superficial growth consisting of minute hyphae produced especially on living plants or organic matter such as wood, paper or leather. Both mold and mildew produce distinct offensive odours, and both have been identified as the cause of certain human ailments.
Powdery mildew is a fungal disease that affects a wide range of plants. Powdery mildew diseases are caused by many different species of ascomycete fungi in the order Erysiphales. Powdery mildew is one of the easier plant diseases to identify, as its symptoms are quite distinctive. Infected plants display white powdery spots on the leaves and stems. The lower leaves are the most affected, but the mildew can appear on any above-ground part of the plant. As the disease progresses, the spots get larger and denser as large numbers of asexual spores are formed, and the mildew may spread up and down the length of the plant.
Gerbera jamesonii is a species of flowering plant in the genus Gerbera belonging to the basal Mutisieae tribe within the large Asteraceae family. It is indigenous to South Eastern Africa and commonly known as the Barberton daisy, the Transvaal daisy, and as Barbertonse madeliefie or Rooigousblom in Afrikaans. It was the first species of Gerbera to be the subject of a scientific description, studied by J. D. Hooker in Curtis's Botanical Magazine in 1889.
Uncinula necator is a fungus that causes powdery mildew of grape. It is a common pathogen of Vitis species, including the wine grape, Vitis vinifera. The fungus is believed to have originated in North America. European varieties of Vitis vinifera are more or less susceptible to this fungus. Uncinula necator infects all green tissue on the grapevine, including leaves and young berries. It can cause crop loss and poor wine quality if untreated. The sexual stage of this pathogen requires free moisture to release ascospores from its cleistothecia in the spring. However, free moisture is not needed for secondary spread via conidia; high atmospheric humidity is sufficient. Its anamorph is called Oidium tuckeri.
Erysiphales are an order of ascomycete fungi. The order contains one family, Erysiphaceae. Many of them cause plant diseases called powdery mildew.
Blumeria graminis is a fungus that causes powdery mildew on grasses, including cereals. It is the only species in the genus Blumeria. It has also been called Erysiphe graminis and Oidium monilioides or Oidium tritici.
Erysiphe cruciferarum is a plant pathogen of the family Erysiphaceae, which causes the main powdery mildew of crucifers, including on Brassica crops, such as cauliflower, cabbage, broccoli, and Brussels sprouts. E. cruciferarum is distributed worldwide, and is of particular concentration in continental Europe and the Indian subcontinent. E. cruciferarum is an ascomycete fungus that has both sexual and asexual stages. It is also an obligate parasite that appears to have host specificity; for example, isolates from turnip will not infect Brussels sprout, and vice versa. While being a part of the family Erysiphaceae, it belongs to those members in which the conidia are formed singly and whose haustoria are multilobed.
Brasiliomyces malachrae is a species of fungus in the family Erysiphaceae. It is a plant pathogen that grows on Gossypium, Lavatera assurgentiflora, Malachra capitata, Malvastrum coromandelianum, and species of Malvaceae. It is found in South America.
Erysiphe heraclei is a plant pathogen that causes powdery mildew on several species including dill, carrot and parsley.
Microsphaera penicillata is a plant pathogen that causes powdery mildew on sycamore.
Oidium mangiferae is a plant pathogen that infects mango trees causing powdery mildew. Powdery mildew of mango is an Ascomycete pathogen of the Erysiphales family that was initially described by Berthet in 1914, using samples collected from Brazil. O. mangiferae is found in all areas where mangoes have been raised long term, but is particularly widespread in India where both the host and the pathogen are native. Currently no teleomorph stage has been identified, but due to certain morphological characteristics it has been suggested that O. mangiferae belongs in the Erysiphe polygony group. Mango is the only known host for this pathogen, though O. mangiferae appears to be identical to fungi responsible for powdery mildew diseases on various other plant species, particularly oak, though some differences may be observed. In particular, the number of cells in conidiophores varies from 2 on mango to 3-5 on oak. O. mangiferae has been known to infect oak leaves in the laboratory, however due to the lack of a known teleomorph stage O. mangiferae is still considered to only be a pathogen of mango. Recent analysis of its ribosomal DNA suggests it is conspecific with Erysiphe alphitoides, the causative agent of powdery mildew in European oaks.
Podosphaera fuliginea is a plant pathogen that causes powdery mildew on cucurbits. Podosphaera fuliginea and Erysiphe cichoracearum are the two most commonly recorded fungi causing cucurbit powdery mildew. In the past, Erysiphe cichoracearum was considered to be the primary causal organism throughout most of the world. Today, Podosphaera fuliginea is more commonly reported.
Erysiphe is a genus of fungi in the family Erysiphaceae. Many of the species in this genus are plant pathogens which cause powdery mildew.
Uncinula is a genus of fungi. Its species are plant pathogens that cause powdery mildew diseases on various plant hosts. The genus is characterized by its dark chasmothecia which bear filamentous, hyaline appendages with hooked tips. Over one hundred species have been described from mostly dicotyledenous hosts. Braun and Takamatsu (2000) suggested that Uncinula should be considered a later synonym of Erysiphe; not all subsequent researchers have accepted their conclusions.
Erysiphe alphitoides is a species of fungus which causes powdery mildew on oak trees.
Ampelomyces quisqualis is an anamorphic fungus that is a hyperparasite of powdery mildews. This parasitism reduces growth and may eventually kill the mildew. These mycoparasites can live up to 21 days on mildew-free host plant surfaces, attacking powdery mildew structures as soon as they appear. A. quisqualis is used as the active ingredient in a commercial fungicide.
Pityopsis ruthii is a rare species of flowering plant in the family Asteraceae known by the common name Ruth's golden aster. It is endemic to the US state of Tennessee, where it is known only from Polk County. It is threatened by the modification of its habitat. It is a federally listed endangered species.
Erysiphe azerbaijanica is a species of powdery mildew in the family Erysiphaceae. It is found in Azerbaijan, where it grows on the leaves of sweet chestnut trees.
Golovinomyces orontii is a species of fungus that causes powdery mildew disease and it is in the family Erysiphaceae. It is an obligate biotroph that infects plants in several families including Acanthaceae, Asteraceae, Brassicaceae, Cucurbitaceae, and Lamiaceae.
Erysiphe platani, also known as sycamore powdery mildew, is a fungus native to North America that now infects sycamore tree species worldwide. Infections may spread rapidly in urban settings with large groups of young trees or in plant nurseries. This mildew thrives when there are high humidity conditions during the growing season.
