Random amplified polymorphic DNA (RAPD) markers were used to estimate genetic relationship and diversity of Fusarium species associated with pink ear rot of maize. Three Fusarium species – F. verticillioides, F. temperatum and F. subglutinans sensu stricto were collected from contaminated corn kernels. A collection of 41 randomly selected Fusarium isolates (16 F. verticillioides, 16 F. temperatum and nine F. subglutinans sensu stricto) was screened for polymorphism with thirty decamer primers. Seventeen primers that had generated a high number of polymorphic loci were used for the analysis of genetic diversity. The primers yielded a total of 146 polymorphic loci, an average of 8.59 polymorphic bands per primer. The percentage of polymorphic bands (%P) was 46.1%. The RAPD-based UPGMA analysis demonstrated that although F. temperatum and F. subglutinans s.s. form two distinct groups they are more similar to each other than to F. verticillioides. Fusarium verticillioides was the most heterogenous species (Nei’s genetic diversity 0.180), while the least heterogenous one was F. subglutinans s.s. whose genetic diversity was 0.098. The analysis of the translation elongation factor 1-α and β-tubulin gene sequences as well as the mating type ratio were employed to support the RAPD data.

Plant essential oils of six aromatic herb species and interspecies hybrids of the family Lamiaceae – chocolate mint (Mentha piperita × ‘Chocolate’), pineapple mint (Mentha suaveolens ‘Variegata’), apple mint (Mentha × rotundifolia), spearmint (Mentha spicata), orange mint (Mentha × piperita ‘Granada’) and strawberry mint (Mentha × villosa ‘Strawberry’) – were investigated for antimicrobial effects against plant pathogenic bacteria: Agrobacterium tumefaciens, Pseudomonas syringae pv. syringae and Xanthomonas arboricola pv. corylina. The screening was carried out in vitro on agar plates filled with the target organism. All essential oils screened exhibited a higher level of antibacterial activity against A. tumefaciens and X. arboricola pv. corylina than streptomycin used as a standard in all tests. The antimicrobial effect of streptomycin and five mint oils was at the same level for P. syringae pv. syringae. There were no significant differences in the influence of the chocolate mint oil on the growth inhibition of all bacteria tested. Plant essential oils from pineapple mint, apple mint, spearmint and strawberry mint showed the weakest antimicrobial activity against P. syringae pv. syringae and the strongest towards A. tumefaciens and X. arboricola pv. corylina. The essential oils from strawberry mint, pineapple mint, spearmint and apple mint had the strongest effect on A. tumefaciens, and the lowest inhibitory activity was exhibited by the chocolate mint and orange mint essential oils. X. arboricola pv. corylina was the most sensitive to the strawberry mint, pineapple mint and spearmint oils. The chocolate mint oil showed the greatest activity against P. syringae pv. syringae.

Key message Comprehensive management of urban greenery is a key approach to control fungal diseases of trees and shrubs to avoid the deterioration in their health status. Abstract Preliminary investigations on the health status related to fungal diseases of trees and shrubs growing in four green squares in Warsaw were conducted in 2017–2019. The examined plants were affected by diseases that are commonly identified in urban greenery, e.g., powdery mildew (causal agents: Sawadaea tulasnei, S. bicornis, Podosphaera leucotricha, Podosphaera sp., Erysiphe alphitoides, E. magnifica, E. berberidis, E. flexuosa and E. adunca), rusts (Gymnosporangium sabinae, Melampsora laricis-populina), apple scab (Venturia inaequalis), tar spot of maple (Rhytisma acerinum), and oyster mushroom (Pleurotus ostreatus). The causal agents of the diseases were identified based on their morphological (macro- and microscopic) features. Preventing and managing fungal plant diseases and reduction of their effects are the key tasks in conscious management of urban greenery. To address this issue, the study presents basic guidelines based on the application of various recommended actions and good practices, which constitute a comprehensive and sustainable strategy for integrated protection of trees and shrubs against these diseases. The implementation of the strategy for complex management of urban greenery is a crucial measure aimed at maintenance of a high health status of urban plants.

Phlebiopsis gigantea (Fr.) Jülich has been successfully used as a biological control fungus for Heterobasidion annosum (Fr.) Bref., an important pathogen of pine and spruce trees. The P. gigantea species has been known for many years, but our understanding of the relationship between various isolates of this fungus has been substantially improved through the application of DNA sequence comparisons. In this study, relationships between P. gigantea and selected Basidiomycota species was determined, based on elongation factor 1-alpha (EF1α) partial DNA sequence and in silico data. A total of 12 isolates, representing the most representatives of P. gigantea, with diverse geographic distributions and hosts, were included in this study. Phylogenetic trees generated for sequences obtained in this research, grouped the European taxa of P. gigantea and partial sequence of the genome deposed in NCBI database, in a strongly supported clade, basal to the rest of the strains included in the study. P. gigantea isolates originating from Poland, Finland, Sweden, Great Britain and partial sequence of genome formed a monophyletic group. Within this group, isolates of P. gigantea constituted two subclades, showing their partial difference like the two SNPs (single nucleotide polymorphisms) between one and the rest of isolates. The intron and exon relationships among P. gigantea isolates were moreover resolved. The results obtained using the EF1α region should be useful in the selection of more efficient P. gigantea isolates for limiting forest tree root pathogens.

S u m m a r yThe aim of the work was to study the development of pseudothecia of M. graminicola. The experiment was carried out in 2002/2003. Wheat leaves collected at Koñczewice (near Toruñ), S³upia Wielka (near Poznañ) and Kromìøí• (Czech Republic) were kept on an experimental field in Warsaw. The pseudothecia were observed under the light and transmission electron microscopy.The first pseudothecia were observed on the dead leaves at the end of July. The largest number of fruiting bodies were noted in October.During the whole period of observation fruiting bodies contained asci in several stages of development. Most of them were immature. In spring the pseudothecia were not found.

The activity of essential oils from Eucalyptus globulus, Pinus silvestris, Lavandula angustifolia, Juniperus virginiana, Rosmarinus officinalis and Citrus paradise against the soft-rot pathogens Pectobacterium carotovorum subsp. carotovorum, Pectobacterium atrosepticum, Pectobacterium parmentieri and Dickeya solani was determined in vitro. The antibacterial activity of the essential oils will be evaluated using the disk-diffusion method by Kirby-Bauer [Bauer et al. 1966]. It was found that all the presented essential oils varied in antimicrobial activity against the four bacterial strains. No differences in the influence of streptomycin on inhibition of growth of the four bacterial strains were observed. Among six tested plants, essential oils from P. sylvestris had the strongest inhibitory effect on the growth of soft rot bacteria from Pectobacterium genus. This paper constitute the first report on the activity of the essential oils obtained from J. virginiana against soft rot bacteria. They are also the first report on the activity of the essential oils obtained from E. globulus, P. silvestris, L. angustifolia and C. paradisi against P. atrosepticum, P. parmentieri and D. solani as well as on the activity of the R. officinalis essential oils against P. atrosepticum and P. parmentieri.

Raspberry (Rubus idaeus L.) and blackberry (Rubus fruticosus L.) are infected by at least 29 viruses, including the Tomato black ring virus (TBRV) (Martin et al. 2013). TBRV belongs to the genus Nepovirus (subgroup B) of the family Secoviridae and is listed as a plant pathogen in over 40 countries. TBRV infects a wide range of herbaceous and woody plants. In Poland, TBRV has been described on the plants of the following species: Tagetes patula, T. erecta, Cucumis sativus, Cucurbita pepo, Lactuca sativa, Solanum tuberosum, S. lycopersicum, Sambucus nigra, and Robinia pseudoacacia (Jończyk et al. 2004, Hasiów-Jaroszewska et al. 2015). To this date, there is no information on the incidence of TBRV in raspberry and blackberry in Poland. In the spring of 2019, 52 blackberry leaf samples and 408 raspberry leaf samples were collected from 4 plantations located in central Poland. None of the raspberry plants (cvs. Glen Ample, Polka, Sokolica), nor the blackberry plants (cvs. Thornfree, Polar, Gaj, Kotata) exhibited viral symptoms. Enzyme-linked immunosorbent assay (ELISA) was carried out for extracts from the 460 collected leaf samples to detect TBRV using commercial antisera (Loewe Biochemica GmbH, Germany). The results indicated that 9 samples (4 blackberry, 5 raspberry) were infected with TBRV. The isolates of the virus were transferred by sap inoculation and maintained in Nicotiana tabacum cv. Xanthi. Systemic ringspot, necrosis and patterned lines were observed on tobacco leaves. The presence of the virus in tobacco leaf samples was confirmed by reverse transcription PCR (RT-PCR). Total RNA was extracted from all 9 samples using the silica capture (SC) method described originally by Boom et al. (1990) and adapted to the detection of plant viruses by Malinowski (1997). Part of the CP gene was amplified with the CPF (5’-GCCTGTCTCTCTCGCAATG-3’) and CPR (5’-AAGGAGCCAAACTGAAATGT-3’) primer pair (Hasiów-Jaroszewska et al. 2015). Amplicons of the expected size (763 bp) were obtained for each sample. The amplified products were purified, sequenced in both directions, deposited in GenBank and assigned accession numbers: MT507387 to MT507390 and MT507394 for the isolates from Rubus idaeus and MT507391 to MT507393 and MN954654 for the isolates from Rubus fruticosus, respectively. The 9 newly obtained TBRV CP gene sequences, together with the 25 isolates deposited in GenBank, were aligned by ClustalW. The isolates obtained in this study showed a 99.0-100% nucleotides (nt) and a 98.7-100% amino acids (aa) identity in the part of the CP, respectively. Comparison of the part of the CP of the 4 blackberry and the 5 raspberry TBRV isolates with 25 TBRV isolates available in GenBank showed a 80.6-97.8% nt and a 87.9-99.5% aa identity, respectively. The results of the phylogenetic analysis have revealed that the TBRV isolates obtained in this study are closely related to 3 Polish isolates (AY157994, KR139941, KR139951) and 1 Bioreba ctrl Switzerland isolate (KT923164). These findings are of epidemiological significance due to the fact that TBRV was detected on symptomless Rubus plants, which therefore represent a reservoir of the virus and a threat in case of a symptomatic infection of sensitive cultivars. Accordingly, the results will assist in using appropriate strategies for reducing TBRV incidence in Rubus-growing areas. Moreover, this is, to the best of our knowledge, the first report of TBRV in raspberry and blackberry in Poland.

Based on two-year experiments on inoculated corn, including genotypes of sweet corn (Zea mays var. saccharata) and popcorn (Zea mays var. everta), the analysis of fumonisin FB 1 content in kernels was performed. Infection degree of sweet corn was 2.00 and 2.13, which was distinctly stronger than infection of popcorn cobs (0.52 and 1.05). Despite of higher disease rating of Zea mays var. saccharata, the most dynamic increase in fumonisin FB 1 biosythesis was observed in kernels of Zea mays var. everta. During the two cropping seasons, the mean level of FB 1 in sweet corn ranged from 0.52 to 6.94 µg g-1 , while in popcorn kernels from 0.96 to 28.49 µg g-1 in the 1 st and 8 th week after inoculation. Botanical varieties of maize as well as physiological state of kernels, determined by the water, amylose and starch contents, influenced on infection degree by Fusarium verticillioides and level of ear contamination by fumonisin FB 1. Efficiency of biosynthesis of mentioned metabolites was inversely proportional to kernel water content.