Tar Spot (Maple)
Rhytisma acerinum
Basic Details
Description
Taxonomy
Features
Translations
Basic Details
NameTar Spot (Maple)
DescriptionTar spot produces large, shiny black lesions that look like drops of tar on maple leaves. Identify these raised spots to understand why your tree might be dropping leaves early.
TypeFungus
FamilyRhytismataceae
GenusRhytisma
Taxonomy & Features
PhylumAscomycota
SubphylumPezizomycotina
ClassLeotiomycetes
OrderRhytismatales
Features
- A common and highly visible fungal disease affecting many species of maple trees, caused by various species of the fungus Rhytisma
- Initial symptoms in spring begin as small, light green or yellow-green spots on the upper surface of the leaf
- By late summer, these spots develop into prominent, raised, shiny black lesions (up to 1.5 cm) that resemble drops of liquid tar
- The black 'tar' is actually a mass of fungal tissue called a stroma, which protects the fungus as it overwinters on fallen leaves
- Heavily infected trees may drop their leaves prematurely, but the disease is primarily aesthetic and rarely causes long-term harm to tree health
- The fungus overwinters on the ground in fallen leaves. In spring, it produces spores that are released during rainy periods to infect new leaves
- Under the black surface, the fungus produces specialized structures that only release their spores when the leaf tissue becomes wet the following spring
- It is most common in shaded areas or in years with exceptionally wet and cool spring weather
- Control primarily through sanitation: rake and destroy all fallen maple leaves in the autumn to remove the overwintering spore source
- Chemical fungicides are generally not recommended for landscape trees as the impact of the disease is purely cosmetic
Names in Different Languages
Latin / ScientificRhytisma acerinum
English (Alternate)Maple tar spot
Hindiमेपल का टार स्पॉट (Maple ka tar spot)
Tamilமேப்பிள் இலை கரும்புள்ளி (Maple ilai karumpulli)
Teluguమేపుల్ తారు మచ్చ తెగులు (Maple taru machha tegulu)
Malayalamമേപ്പിൾ ഇലയിലെ കറുത്ത പുള്ളികൾ (Mēppiḷ ilayile kaṟutta puḷḷikaḷ)
Kannadaಮ್ಯಾಪಲ್ ಎಲೆಯ ಕಪ್ಪು ಮಚ್ಚೆ ರೋಗ (Myāpal eleya kappu macce rōga)
Sanskritकृष्ण-बिन्दु-रोग (Kṛṣṇa-bindu-roga)
Bengaliমেপল এর টার স্পট (Maple er tar spot)
Frenchtache goudronneuse de l'érable
Russianчерная пятнистость клена (chernaya pyatnistost' klena)
Spanishmancha de alquitrán del arce
GermanAhornrunzelschorf
