Marek Kobza

Distribution and Population Structure of the Chestnut Blight Fungus in Romania

C. parasitica were isolated and characterised. Based on canker and isolate morphology (culture morphology and the Bavendamm test), both virulent and hypovirulent samples were isolated; hypovirulent isolates were found at only one locality. Two vegetative compatibility types corresponding to EU-12 and EU-2 were identified among isolates. Both mating types were found, with a dominance of MAT-1 in southern Romania and MAT-2 in northern Romania.

Scab disease of firethorn at selected localities in Slovakia

J������� G., I������ H., A��������� K., K���� M., Č�������� A. (2004): Scab disease of firethorn at selected localities in Slovakia. Plant Protect. Sci., 40: 42–48. The health state of firethorn, Pyracantha coccinea, was evaluated in different types of functional urban greenery at locations in Slovakia during 2001 (34 sites) and 2002 (18 sites). The occurrence of scab disease, caused by the fungus Spilocaea pyracanthae, was recorded. The degree of damage to firethorn fruits was evaluated; it ranged from 3.6% to 98.8% (2001) and from 9.1% to 38.5% (2002). Germination of conidia of the fungus ranged between 42 and 50% at 24–25°C after 24 h, and from 49% to 61% after 48 h. The germination of conidia collected on different parts of the plants from July to September was compared. Conidia taken from olive-green spots on fruits in September had the highest germination (53–89%).

Extensively damaged trees tested with acoustic tomography considering tree stability in urban greenery

Key messageDamaged area of five tree species was determined by acoustic tomography. Final accuracy of 83% was found as satisfactory and proven suitability for overall tree stability assessment.AbstractObjectives of study were to assess the accuracy and reliability of the acoustic tomography technique for detecting internal structural defects compared to visual assessment on extensively damaged trees of five species in urban greenery. Tomography was realized by Fakopp 3D acoustic tomograph tool. Several types of structural defects were determined, such as heartwood and sapwood decay, internal and lateral cracks, ring shake and hollow. Acoustic tomography inspection revealed correct detection of damage in all disc samples involved in study. Accuracy of damaged area determination reached 90%. Total accuracy determination for both area and location of damage was 83%. Overestimation of damaged area was observed in eight samples, contrary to seven underestimated samples. Difference in estimated false-positive area in comparison to false-negative area was minimal. Irregularity of cross section shape does not affect the final accuracy of tomograph. Accuracy is not influenced by diameter of tree trunk. We determined strong positive correlation between real area of damage and results of tomography (r = 0.75; p = 0.001). Acoustic tomography provides satisfactory accuracy in damage area determination inside tree trunk and for overall tree stability assessment on even extensively damaged trees in urban greenery.

Spread and population structure of Cryphonectria parasitica in a young chestnut orchard in Slovakia

The chestnut blight pathogen Cryphonectria parasitica was studied in a chestnut collection composed of both seedlings and grafts derived from selected Castanea sativa and C. sativa × C. crenata trees located in south-east Slovakia, near village Príbelce on an area of approximately 3.5 ha. The study was conducted during eight years (2003–2010). During this period 133 trees were infected, which represents 59.82% of chestnut trees of all chestnut accessions. Based on the phenotype of the fungus culture and the type of cankers in the field, all isolates were determined to be virulent. No hypovirulent strains were found. No vegetative compatibility (vc) type diversity was observed. More than 130 isolates were analyzed for vc and all were in single vc type, which was identical with EU 12. All isolates assayed for mating type were MAT-1. No perithecia were observed. No significant differences were found between the proportion of cankered and dead cankered trees in seedlings and grafts of hybrid origin (C. sativa × C. crenata) and of C. sativa origin. However, particular seedlings and grafts of hybrid origin seemed to exhibit certain resistance to chestnut blight.