engleski

First report of Septoria leaf spot of lavandin caused by Septoria lavandulae in Croatia

Lavandula × intermedia, commonly known as lavandin, is an aromatic and medicinal perennial shrub widely and traditionally grown in Croatia. In June 2012, severe foliar and stem symptoms were observed on approximately 40% of plants growing in a commercial lavandin crop in the locality of Banovo Brdo, Republic of Croatia. Initial symptoms on lower leaves included numerous, small, oval to irregular, grayish brown lesions with a slightly darker brown margin of necrotic tissue. Further development of the disease resulted in yellowing and necrosis of the infected leaves followed by premature defoliation. Similar necrotic oval-shaped lesions were observed on stems as well. The lesions contained numerous, dark, sub-globose pycnidia that were immersed in the necrotic tissue or partly erumpent. Based on the morphological characteristics, the pathogen was identified as Septoria lavandulae Desm., the causal agent of lavender leaf spot. Pathogenicity of one selected isolate (428-12) was tested by spraying 10 lavandin seedlings (8 weeks old) with a conidial suspension (106 conidia/ml) harvested from a 4-week-old monoconidial culture on PDA. After 5 to 7 days, leaf spot symptoms identical to those observed on the source plants developed on all inoculated seedlings and the pathogen was successfully re-isolated. Morphological identification was confirmed by amplification and sequencing of the internal transcribed spacer (ITS) region of rDNA. Sequence analysis of ITS region revealed at least 99% identity between the isolate 428-12 (GenBank Accession No. KF373078) and isolates of many Septoria species ; however, no information was available for S. lavandulae. To our knowledge, this is the first report of Septoria leaf spot of lavandin caused by S. lavandulae in Croatia.

Septoria lavandulae; Croatia; lavandin

nije evidentirano