Didymella ligulicola
| Didymella ligulicola | ||||||||||||
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| Scientific name | ||||||||||||
| Didymella ligulicola | ||||||||||||
| ( KF Baker , Dimock & LH Davis ) Arx |
Didymella ligulicola is a kind from the order of pleosporales in the department of hose mushrooms (Ascomycota). The fungus usually occurs as an anamorphic (secondary fruit form) and is then called Ascochyta chrysanthemi F. Stevens . Didymella ligulicola is the name of the teleomorphs (main fruit forms). The species is the causative agent of Ascochyta disease in chrysanthemums ( Chrysanthemum ), zinnias ( Zinnia ) and other sunflower plants (Asteraceae). It is believed that the species originated in North America , but it can now be found almost worldwide.
Life cycle
The fungus overwinters as a mycelium or in the form of spores . In winter or early autumn, the ascospores ripen on infected plant tissue and can then be spread by the wind all year round. Pycnidia tend to form on flower buds and stems, less often on stems and leaves. The conidia only open in moist conditions and release their asexually formed conidiospores in thick drops, which leave characteristic stripes on the plant. They are spread via the wind or animals grazing along the plant. In the case of cultivated plants, the transmission takes place particularly easily by humans when watering. From the conidiospores a mycelium develops, which penetrates the epidermis and spreads in the tissue within and between the plant cells, richly branched with numerous short cells.
Infested parts of the plant show a brownish, moist decay due to the fungus growth and released toxins. All parts of the plant can be infected, but flowers and freshly cut areas are particularly susceptible.
morphology
The pycnidia are depressed spherical. On flower petals they are heaped around 70 by 180 µm in size, on other parts of the plant they are around 100 by 300 µm in size and scattered. The pycnidospores are hyaline, ovoid to cylindrical or irregularly shaped and have one or more septa. The less common pseudothecia are round, dark brown and measure 96 to 224 µm in diameter. The ascospores are translucent to grayish, spindle-shaped to elliptical with a septum.
swell
- Didymella ligulicola . In: CABI and EPPO (eds.): Data Sheets on Quarantine Pests . ( online [PDF; 36 kB ]).