Where trees cannot grow - Particulate matter accumulation by urban meadows.

It has already been proven that trees and shrubs, can efficiently remove particulate matter (PM) from air. However, almost nothing is known about PM accumulation by herbaceous plants (grasses and forbs) found in urban meadows. Meadows, unlike trees and shrubs, can be located close to roads, one of the main sources of PM in cites. The aim of this study was to investigate the tolerance to urban condition and PM accumulation in the immediate roads vicinity of selected plants species in urban meadows. PM accumulation of annual and perennial meadows was compared with that of lawns. Results were interpreted in the context of species composition, biomass production, soil conditions and ambient PM concentrations. Of the species grown in annual meadows, the highest PM accumulation was found in Achillea millefolium L., Chenopodium album L. and Echium vulgare L., while Centaurea scabiosa L., Echium vulgare L. and Convolvulus arvensis L. accumulated the largest amounts of PM in perennial meadows. PM deposition on plants was positively correlated with a feathery leaf shape. For species in the annual meadows, a positive correlation was also found between PM accumulation and the wax content on plants. The presence of hairs on leaves, leaf size and plant growth pattern had no effect on PM deposition on plants. PM accumulation in one square metre of urban meadow was on average greater than that of lawn, regardless of meadow species' composition, age and location. The greatest accumulation of PM was found in a perennial meadow with low biodiversity but the greatest biomass. It would appear that the biomass produced by meadows and canopy structure has a crucial impact on the amount of PM accumulated by meadow plants. The results obtained indicate that meadows could be an important element of nature-based solutions for mitigating air pollution in urbanised areas.

Urban wastelands: On the frontline between air pollution sources and residential areas.

In urban areas, particulate matter (PM) represents an increasing threat to human health. The ability of plants in parks and along roads in cities to accumulate PM has already been demonstrated, but nothing is known about the effect of wasteland vegetation on air quality, despite a significant proportion of greenery in polluted areas being on wastelands. The aim of this study was to document the accumulation of PM and trace elements (TE) by wasteland species (Robinia pseudoacacia L., Populus × canescens (Aiton) Sm., Acer negundo L., Solidago gigantea (Aiton) and Poaceae) growing on Central European urban wastelands with differing levels of air pollution. On average, the largest amounts of PM accumulated on the foliage of R. pseudoacacia and S. gigantea, and the smallest amounts accumulated on P. × canescens leaves. However, accumulation of PM depended more on the distance from the emission source than on species selection, and was higher on the polluted wasteland where the plants' gas exchange was the lowest. The results also suggest that in order to effectively accumulate PM from the air, it is critical to have the correct configuration of plants, with the wasteland vegetation having a layered structure and layers differing in PM retention, as shown in this study using the examples of R. pseudoacacia (a tall tree with low PM retention) and S. gigantea (below-tree vegetation with high PM retention). P. × canescens accumulated the highest concentrations of Cd and Zn, S. gigantea accumulated the highest concentration of Cu, and Poaceae accumulated the highest concentrations of Cr and Ni. These findings have implications for urban vegetation management in areas where there is no organised greenery, and offer proof that vegetation in wasteland areas should be maintained since it is an excellent tool for reducing concentrations of PM at its place of origin.

Valdensinia heterodoxa Peyronel as a New Pathogen of Blueberry in Poland.

Valdensia leaf blight on blueberry in Poland was reported in one commercial nursery plantation near Prazmów, Mazovia voivodship, where heavy defoliation was observed on cv. Bluecrop, grown in nursery pots, in August 2011. Older fruiting bushes were only slightly affected by the disease. Initial symptoms of the disease were small, oval to circular zonated necrosis surrounded with dark brown borders that enlarged on the leaves throughout the canopy. Multicellular, hyaline or light brown, star-shaped conidiospores were observed on the necrotic areas. The mean length of 50 conidiospores from the end of head to the end of arm apex was 307 to 348 µm (4). Eight single-spore isolates of the fungus were obtained. Single conidiospores were picked up from necrotic spots on leaves and transferred with sterile needle on potato dextrose agar (PDA) and incubated at 20°C under ambient light. After 10 days of incubation, total DNA was extracted. Amplification of the internal transcribed spacer (ITS) region of rDNA was done using primers ITS1F and ITS4A (1). PCRs were carried out as follows: initial denaturation at 94°C for 2 min, denaturation at 94°C for 1 min, annealing at 57°C for 1 min, extension at 72°C for 1 min, and final extension at 72°C for 5 min for 28 cycles (Applied Biosystems Veriti 96 Wel Thermal Cycler). Amplicons, which were approximately 520 bp, were sequenced and nucleotide sequences were analyzed by Clustal W2EBI. The sequences of all eight isolates showed 100% similarity to each other and were compared with sequences stored in GenBank using BLAST. Sequences were 525 bp long and showed 100% homology to Valdensinia heterodoxa Peyronel, Sclerotiniaceae (anamorph: Valdensia heterodoxa Peyronel) from Japan and Norway (Accession Nos. AB663682 and Z81447, respectively) (3). The sequence from one isolate was submitted to GenBank (Accession No. KF212190). To fulfill Koch's postulates, each of the eight isolates was used to inoculate 20 healthy young leaves of Vaccinium corymbosum L. cv. Bluecrop and bilberry (V. myrtillus L.) (10 leaves per plant). Mycelial plugs 5 mm in diameter were taken from PDA cultures, approximately 20 days old, and used as inoculum and placed in the center of each leaf and moistened with sterile distilled water. Mycelium-free plugs were used as control. Inoculated leaves were placed in plastic box and incubated at 20°C in laboratory for 5 days, at which time small necrotic lesions consistent with initial symptoms of the disease were observed. Isolates obtained from these symptoms were morphologically identical to those used for inoculation. Control leaves did not show any disease symptoms. Valdensia leaf blight occurrence may be attributed to rainy July and August 2011 and long presence of water on soil surface. In Poland, Valdensinia heterodoxa causes heavy defoliation of Vaccinium myrtillus in pine stands and is a common pathogen of some herbaceous plants (2). To our knowledge, this is the first report of Valdensia leaf blight on highbush blueberry in Poland. References: (1) I. Larena et al. 75:187, 1999. (2) W. Mulenko and S. Woodward. Mycologist 10:69, 1996. (3) S. Nekoduka et al. J. Gen. Plant Pathol. 78:151, 2012. (4) S. Zhao and S. F. Shamoun. Mycology 1:113, 2010.

First Report of Microcyclosporella mali Causing Sooty Blotch and Flyspeck Disease on Plum in Poland.

Sooty blotch and flyspeck (SBFS), a disease caused by a complex of fungi, results in substantial economic losses for commercial growers of scab-resistant apple (Malus × domestica Borkh.) cultivars in Poland. However, many species causing SBFS in Poland are unidentified and sources of inoculum are uncertain. In August 2009, signs of SBFS were noted on fruit of plum (Prunus domestica L., cvs. Sweet Common Prune and Oullins Golden Gage) in orchards near Mostki in central Poland. Colonies consisted of olive green-to-black mycelial mats with few sclerotium-like bodies; infections ranged in severity from scattered spots to nearly complete coverage of the fruit surface. Ten of these colonies were isolated on potato dextrose agar (PDA). After 10 days of incubation at 22°C, total DNA was extracted; amplification of the internal transcribed spacer (ITS) region of rDNA utilized primers ITS1 and ITS4 (1). Nucleotide sequences were analyzed by ClustalW and compared with sequences in GenBank using BLAST. Sequences showed 99 to 100% homology to Microcyclosporella mali (2), which was formerly assigned as Pseudocercosporella sp. (1). Sequences from five isolates were submitted to GenBank (Accession Nos. HM101275, HM101276, HM101277, HM101278, and HM101279). Morphological characteristics-conidiogenous cells integrated, sympodial and polyblastic; conidial scars nonthickened and inconspicuous; conidia hyaline, subcylindric, narrow, straight or very slightly curved, truncate at the base and obtuse at the apex, often catenulate in simple or branched chains, with one (commonly) to five septa (12.5 × 2.6 to 50.7 × 4.0 µm)-were consistent with descriptions of M. mali (2). To fulfill Koch's postulates, each of the 10 isolates was used to inoculate three healthy apple fruit (cv. Golden Delicious) that had been previously washed under tap water and disinfested with 70% ethanol. After fruit were swabbed with cotton plugs that had been saturated with a suspension of spores in sterile distilled water (SDW), inoculated fruit were placed on filter paper that had been moistened with SDW, then sealed in foil bags and incubated at 22°C. When bags were removed 5 weeks later, dark colonies had appeared on the fruit. Isolates obtained from these colonies were morphologically identical to those used for inoculation. Control (SDW-inoculated and noninoculated) fruit that were incubated in the same manner developed no colonies. To our knowledge, this is the first report of SBFS on plum caused by M. mali in Poland; it had previously been noted as part of the SBFS complex on apple in Germany and Slovenia (2) and on apple and plum in the United States (3). References: (1) J. C. Batzer et al. Mycologia 97:1268, 2005. (2) J. Frank et al. Persoonia 24:93, 2010. (3) J. Latinovic et al. Plant Dis. 91:1685, 2007.