Phytophthora is a genus of
plant-damaging Oomycetes fungi. The majority of Phytophthora
species are primary and very important parasites of woody plants.
According to C.M. Brasier (2009), the number of known potentially
tree damaging species have increased to 60% in 2000. So far, more
than 100 Phytophthora species have been described, but it is
likely that worldwide 200-600 species exist being still unknown to
science. Phytophthora species and its distribution was not
investigated in detail in Lithuania until present. P. infestans
was known to exist in Lithuania before 2004 (Mazelaitis,
Stanevičienė, 1995). Starting from 2004, Z. Jovaišienė have
isolated and identified three Phytophthora species in Rhododendrons
- P. cinnamomi, P. cactorum, and P.
ramorum (Jovaišienė, 2004; Jovaišienė, Lane, 2006).
A group of scientists representing Environmental Research Centre and Kaunas Botanical Garden of Vytautas Magnus University was formed to maintain Phytophthora investigation in Lithuania. Dr. Adomas Vitas, dr. Rūtilė Pukienė, dr. Vilija Snieškienė, dr. Antanina Stankevičienė currently are the leaders of this group. In 2010-2011, the monitoring of Phytophthora spp. infected deciduous tress was carried out in 22 districts of Lithuania. The field-work was performed in city greeneries, parks, and forests in Lithuania.
So far, 326 deciduous trees were documented with typical disturbance symptoms (Černý and Strnadovaà, 2010) to Phytophthora genus in Lithuania. The highest number of infected trees was assessed in Kaunas City, Zarasai, Jurbarkas, Prienai, and Alytus districts (from 13 to 138). Fifteen host deciduous tree genera were documented until present in Lithuania: Acer, Alnus, Betula, Salix, Quercus, Populus, Aesculus, Fraxinus, Prunus, Morus, Tilia, Ulmus, Frangula, Carpinus, and Corylus. More than a half of infected trees are young individuals growing less than 10 m distances from the water source.
The following bark disturbance symptoms were documented: tarry or rusty spots of exudates on bark, flame-shaped collar necrosis, bleeding bark cracks and fissure usually several metres length. The rusty spots are of variable size. The typical disturbance symptom of young trees is small bleeding spots on stem in comparison to premature and mature trees, where large bleeding spots and bark cracks predominate.