Conifers, a component of beauties of parks and landscapes, are infected with diverse pathogens, especially fungi. In this research, samples were collected from conifers displaying symptoms of disease in parks and landscapes of Rasht in Iran and for the isolation and identification of pathogenic fungi, pieces of infected tissues were placed in PDA and at the next stages in WA, PCA and SNA media and in total, 58 isolates were isolated and identified based on morphological characters. These fungi belonged toAlternaria franseriae, Alternaria tenuissima, Curvularia pallescens, Fusarium sambucinumand Pestalotia sp. Afterward, pathogenicity test of these fungi was done onChamaecyparis lawsoniana, Chamaecyparis lawsoniana ' Minima Aurea', Thuja sp., Juniperus horizontalis, Juniperus chinensisand Cupressus arizonica and to do so, a spore suspension was prepared with the concentration of 5 × 104 spores per ml distilled water and then, the studied plants were inoculated. Final assessments were carried out 10 days later to determine disease intensity. Results showed thatA. franseriae on C. lawsoniana, A. tenuissimaon C. lawsoniana ' Minima Aurea', C. pallescens on C. lawsoniana and J. chinensis, F. sambucinum on J. horizontalisand Pestalotia sp. on C. arizonica and C. lawsoniana ' Minima Aurea', were pathogenic. The most disease severity was caused byA. franseriae on C. lawsoniana and the least disease severity byPestalotia sp. on C. lawsoniana ' Minima Aurea'. Among the studied plants, C. lawsoniana and C. lawsoniana ' Minima Aurea' showed the greatest sensitivity and the most resistance, respectively. Analysis of variance revealed significant differences in disease intensity of the studied fungi. The occurrence of A. franseriae, A. tenuissima and C. pallescens on conifers has been reported for the first time from Iran on conifers.

Family CUPRESSACEAE is the largest coniferous plant family. Essential oils of many species belonging to family CUPRESSACEAE are known to have several biological activities specially antimicrobial activity. The essential oils from aerial parts of Calocedrus decurrens Torr., Cupressus sempervirens stricta L. and Tetraclinis articulata (Vahl) Mast. were prepared by hydrodistillation. The chemical composition of the essential oils has been elucidated by gas chromatography-mass spectroscopy analysis. The prepared essential oils were examined against selected species of Gram- positive, Gram- negative bacteria and Candida species. Broth dilution methods were used to detect minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and minimum fungicidal concentration (MFC). Sixteen compounds were identified in the essential oils of both Calocedrus decurrens and Cupressus sempervirens L. and fifteen compounds were identified in the essential oil of Tetraclinis articulata. d-3-Carene (43.10%), (+)-Cedrol (74.03%) and Camphor (21.23%) were the major constituents in the essential oils of Calocedrus decurrens, Cupressus sempervirens L. and Tetraclinis articulata, respectively. The essential oils showed strong antimicrobial activities against the selected microorganisms in concentration range 0.02 3- 3.03 mL/mL. This study could contribute to the chemotaxonomic characterization of family CUPRESSACEAE. In addition, it proved that the essential oils under investigation possess potential antimicrobial properties.