Sooty blotch and flyspeck
[1] Sooty blotch and flyspeck is a descriptive term for a condition of darkly pigmented blemishes and smudges caused by a number of different fungi affecting fruit including apples, pear, persimmon, banana, papaya, and several other cultivated tree and vine crops.
SBFS fungi also grow on the surfaces of stems, twigs, leaves, and fruit of a wide range of wild plants.
[3] In an 1832 paper written in Latin and published in Philadelphia, Ludwig Schweinitz described the first sooty blotch species as a fungus he named 'Dothidea pomigena'.
[4] By the end of the 20th century three more fungal species had been identified as causes of sooty blotch on North Carolina apples, still based on their morphological type: Peltaster fructicola, Geastrumia polystigmatis and Leptodontium elatius.
[5] The authors broke ground after 160 years of "confusion", stating that "sooty blotch fungi are difficult to isolate due to many contaminating microorganisms on the surface of plant parts".
The authors went back to the original historical deposits at the herbarium of the Academy of Natural Sciences in Philadelphia and found no conidia.
Parsimony analysis, bootstrapping and the minimum evolution principle led to groups of species, further described by conidial and colony morphology.
Thirty isolates fulfilled Koch’s postulates as new species, all Dothideomycetes, 27 were within Dothideales, one was within Pleosporales and two with undetermined ordinal level.
RS5.2, Phialophora sessilis, and Geastrumia polystigmatis, were found only in certain regions, leading to the conclusion that SBFS species differ geographically.
[6] Since then, slow-growing epiphytic fungi often belonging to the Capnodiales have been identified (Gleason et al. 2011), and a new species in 2014, Peltaster cerophilus from Europe.
Similar to the apple scab model it numerically grades risk and degree of infection and can serve as a warning system.
[8] Conventional orchards that spray fungicides against apple scab, treat soot blotch and flyspeck at the same time.
In organic orchards, spraying 4–5 with lime sulphur or coco soap during the main infectious periods is recommended.
