Brown spot needle blight associated with Mycosphaerella dearnessii occurs on Pinus rotundata in the Czech Republic

Lecanosticta acicola is the anamorph of Mycosphaerella dearnessii, the cause of brown spot needle blight on pines. The disease has been recorded in several European countries including Austria, Bulgaria, France, Germany, Spain, Italy Switzerland and former Yugoslavia (e.g. Holdenrieder & Sieber, 1995; La Porta & Capretti, 2000). There are much earlier records of brown spot needle blight in Europe though it is unclear how these were distinguished from Dothiostroma septospora infections producing similar symptoms.

We have now confirmed Lecanosticta acicola in the Czech Republic from samples of bog pine, Pinus rotundata, collected on the 10 June, 2007 from Červené Blato Nature Reserve, South Bohemia (48°51'37" N, 14°48'44" E); 430 metres above sea level. Bog pines 10–40 years-old had severe needle defoliation inside the nature reserve which were absent in pines (P. rotundata, P. sylvestris) in surrounding managed forests. Symptoms begin with the appearance of yellow and brown spots, later becoming bands on first-year needles which then decline from the tip (Fig. 1). Acervuli erupt from needles incubated for two to three days in a moisture chamber (Fig. 2). Conidia are subhyaline, thick-walled, straight to curved, fusiform to cylindrical, with rounded apex and truncate base, 1-5 septate, occasionally slightly constricted at the septa, 3-5 × 21-44 μm. The surface of conidia have small warts or spines (Fig. 3).

After three to four weeks incubation of conidia at 21 °C on 2 % malt extract agar, dark green olive stromatic mycelial colonies produced conidia identical to those detected on incubated needles (Fig. 4). DNA sequences of the ITS region of hyphae from the isolated strain (GenBank Accession. No. EU117117) showed 99-100% similarity with other species of M. dearnessii held in GenBank. A dried specimen of infected needles is preserved in BRNL herbarium (specimen no. 1010), and the fungus has been deposited in the CCF Culture Collection (strain no. 3743).