4/16/2023 0 Comments Propagate cornus mas![]() ![]() Necrosis similar to that observed in the field became visible around the mycelia plugs 4 days after inoculation. Leaf samples were incubated at 20☌ in a humidified chamber. Sterile V8 plugs were placed onto similar wounds of control leaves. mas seedlings and ‘Kazanlashki’ were wiped with 70% ethanol, punctured with a needle, and the wounds inoculated with 5-mm mycelial plugs from a 7-day-old V8 growth plate. Isolates had identical cultural and morphological characteristics, and pathogenicity was tested by laboratory inoculations carried out in 2007 (two isolates) and twice in 2008 (three isolates). The morphological data identified the organism as Phytophthora citricola (1). The pathogen's paragynous antheridia and smooth-walled spherical oogonia (20 to 32 μm in diameter) yielded spherical aplerotic to almost plerotic oospores on V8 medium with an average size of 25 μm. Average sporangium size was 39 (35 to 45) × 31 (20 to 35) μm with a ratio between both parameters of approximately 1.26. ![]() Numerous, ovoid to obpyriform, noncaducous, semipapillate sporangia occasionally with two papilla were observed after 1 or 2 days of incubation at 20☌ in nonsterile soil extract (1). ![]() Isolations from symptomatic leaves, shoots, and rootstocks (three to five samples per plant organ) on potato dextrose agar always revealed a fungus-like organism that formed relatively fast-growing white, radial, petaloid colonies. Necrosis of the leaves and shoots spread toward the older woody tissues and the plantlets died within a couple of weeks. Dark brown, necrotic leaf spots initiated most often from the leaf periphery and quickly covered more than half of the leaf area. Symptoms were identical in both years and expressed on the leaves, young shoots, and adjacent rootstock wood. In the springs of 20, severe, unusual damages were observed on sporadically scattered plantlets of ‘Kazanlashki’ (known also as ‘Kazanlaker’) in a nursery located near Vratza in northwestern Bulgaria. Cornelian cherry dogwood ( Cornus mas) is a widespread species in Bulgaria and some cultivars with large fruits are the subject of propagation. ![]()
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