Stigmina

Sacc., 1880

Stigmina is a of fungal in the Mycosphaerellaceae, established by Saccardo in 1880. in this genus cause leaf spot on a wide range of woody , including conifers and trees. The genus is characterized by superficial sporodochia that develop through , with arising laterally from the lower outer . Transmission occurs primarily via airborne .

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Pronunciation

How to pronounce Stigmina: //stɪɡˈmiː.nə//

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Identification

Stigmina are distinguished from similar fungal by their superficial, flattened sporodochia that develop exclusively through . arise only laterally from the lower, outer of the sporodochium, are macronematous, mononematous, , smooth, unbranched, and 1–2 septate. Conidiogenous cells are brown, monoblastic, integrated, , percurrent with 3–4 annelations. are pale brown, cylindrical to , often curved, thick-walled, verrucose, and 5–8 distoseptate. These features separate Stigmina from Rhizosphaera species, which produce pycnidia rather than sporodochia.

Images

Habitat

occur on living leaves of plants in temperate and tropical regions. Stigmina lautii has been observed on symptomatic needles and adjacent green needles of spruce trees in western North Carolina, suggesting establishment in both diseased and apparently healthy tissue.

Distribution

The has been documented across six continents. Stigmina carpophila occurs throughout Africa, Asia, Australasia, Europe, North America, Central America, and South America. Stigmina lautii has been reported in Canada (Manitoba, Saskatchewan, British Columbia) and the United States (North Carolina). Stigmina deflectens occurs in Austria, Finland, Romania, Ukraine, Canada (Manitoba), and the United States (South Dakota). Stigmina mangiferae has been recorded from tropical and subtropical regions including Australia, Pacific islands, Africa, Asia, and the Caribbean.

Host Associations

Prunus persica - causes shot-hole
Prunus dulcis - almond
Prunus armeniaca - apricot
Prunus avium - sweet cherry
Prunus cerasus - sour cherry
Prunus domestica - plum
Prunus laurocerasus - cherry laurel
Picea pungens - spruce; first US record for Stigmina lautii
Picea abies - Norway spruce; new record for Stigmina lautii
Picea mariana - black spruce
Picea glauca - spruce
Juniperus communis - common juniper
Mangifera indica - mango
Acer macrophyllum - maple; of Stigmina zilleri
Cocos nucifera - coconut; of Stigmina dura
Platanus occidentalis - sycamore
Platanus orientalis - oriental plane
Phoenix dactylifera - date palm and related Phoenix
Anacardium occidentale - cashew; of Stigmina anacardii

Ecological Role

Stigmina function as foliar of . The association of Stigmina lautii with typical needle blight and its presence on both symptomatic and adjacent green needles suggests potential to spruce, though experimental confirmation is lacking for some species.

Human Relevance

cause economically significant leaf spot and shot-hole of stone fruits (peach, cherry, plum, apricot, almond) and other . Stigmina carpophila is a notable of Prunus species worldwide. Stigmina lautii represents an emerging pathogen of ornamental spruce in North America, with first US in 1999. The superficial similarity of Stigmina lautii sporodochia to pycnidia of Rhizosphaera kalkhoffii complicates field of spruce needle diseases.

Similar Taxa

RhizosphaeraRhizosphaera kalkhoffii produces pycnidia that arise through and cause similar needle blight on Picea; distinguished by pycnidial structure versus sporodochial structure of Stigmina

More Details

Taxonomic note

The name Stigmina has been used for both a fungal (Mycosphaerellaceae) and a subtribe of (: Crabronidae). This record addresses the fungal genus.

Morphological variation

Conidial dimensions vary among : Stigmina lautii measure 25–45 × 5–6 μm, while dimensions for other species may differ.

Transmission

Multiple are transmitted by airborne , including S. carpophila, S. mangiferae, S. palmivora, S. millettiae, S. anacardii, S. tinea, S. platani, and S. dura.