Screening of microorganisms for antagonistic activity against pathogenic fungi of Pinus spp

Pine (Pinus) stands cover more than 34% of the forest area and it is one of the most ecologically and economically important trees in Lithuania. However, more than 1% of pine trees are damaged by fungal diseases every year [1]. Therefore, effective control measures should be applied. Biological control is an alternative to conventional management. For this purpose, in this study, pine needles, buds and twigs were collected in 2018. Healthy plant material and (or) with symptoms similar to those caused by Neocatenulostroma germanicum, Lophodermium pinastri and Dothistroma septosporum, was analysed. 340 fungal isolates from native and introduced Pinus spp. trees (P. sylvestris ‘Beuvronensis’, P. mugo ‘Frisia’, P. strobur, P. nigra, P. banksiana xp contorta, P. ponderosa var. scopulorum and P. parviflora ‘Glauca’) were obtained. 102 fungal isolates belonging to 50 morphological groups were subjected for analysis. 23 isolates had a high antagonistic activity against plant pathogenic fungi. As screening of potential biocontrol agents is essential for their further development and suitability to use them for disease management, further research will be followed with effects of the pathogen in vivoBiologijos katedraGamtos tyrimų centrasVilniaus universitetasVytauto Didžiojo universiteta

Effects of natural antimicrobials on Xanthomonas strains growth

The aim of this work was to investigate the most promising natural antimicrobials effective for the growth suppression of Xanthomonas spp. bacteria. The research objects were Xanthomonas spp. strains isolated from tubers and stem of plants growing in Lithuania: Xanthomonas translucens NRCIB X6, X. arboricola NRCIB X7, NRCIB X8, NRCIB X9, and NRCIB X10; the supernatants of lactic acid bacteria Lactococcus lactis strains 140/2, 57, and 768/5, Lactobacillus helveticus strains 14, 148/3, R, and 3, Lb. reuteri 3 and 7, Streptococcus thermophilus 43, Enterococcus faecium 59-30 and 41-2; endophytic bacterial strains Bacillus, Pseudomonas, and Paenibacillus spp.; and essential oils of lavender (Lavandula angustifolia), grapefruit (Citrus paradisi), pine (Pinus sylvestris), thyme (Thymus vulgaris), rosemary (Rosmarinus officinalis), peppermint (Mentha piperita), lemon (Citrus limetta), aqueous extracts of blueberries (Vaccinium myrtillus), and cranberries (Vaccinium vitis-idaea). The antimicrobial activity of tested substances was determined by agar diffusion method. Supernatants of Lb. reuteri strain 7 and Lb. helveticus strains 14, R, 3, and 148/3 were found to have a high antimicrobial activity against Xanthomonas spp. bacteria strains when compared to the positive control—1.0% copper sulfate (diameter of inhibition zones was 28.8 ± 0.7 mm). The diameter of inhibition zones of supernatants ranged from 23.3 ± 0.6 mm to 32.0 ± 0.1 mm. Thyme (2.0%) and lavender (2.0%) essential oils inhibited the growth of Xanthomonas spp. strains. The diameter of the inhibition zones was from 14.7 ± 0.8 mm to 22.8 ± 0.9 mm. The aqueous extracts of blueberries had a weak antimicrobial activity. The diameter of inhibition zones ranged from 11.0 ± 0.2 mm to 13.0 ± 0.2 mm