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Colletotrichum acutatum belongs to polyphagous fungal pathogens and is widespread in many countries on all continents. C. acutatum causes the most serious economic damage in strawberry (Fragaria x ananassa Duch.). Considering the wide variability of the pathogen may be assumed spread to other areas which constitutes danger not only for strawberry, but also other economically important fruit crops, vegetables and fruits.The main objective of our study was to verify the cross infection of eleven C. acutatum isolates from different host plants (strawberry, safflower, lupine, pepper and Hypericum perforatum) to selected host plants (strawberry, pepper and safflower). Two varieties from each of the experimental plant species were selected and virulence of isolates C. acutatum was evaluated.Based on results of statistical evaluation, virulence of C. acutatum isolates was different on strawberry, pepper and safflower. The strawberry variety Pegasus was more susceptible to C. acutatum than the variety Elkas. Isolate 710 from H. perforatum showed the highest virulence for both varieties in terms of index of infection intensity. The pepper variety Pirouet was more susceptible than the variety Cynthia. The highest degree of virulence was found for isolate 29267 from pepper in the variety Cynthia, the highest virulence was proved for isolate 231 from strawberry in the variety Pirouet. No statistical difference was confirmed between susceptibility of the safflower varieties. Isolate 1209 from safflower showed the most important effect on tested plants of safflower. Isolates 710 from H. perforatum, isolate 1209 from safflower, isolate 29267 from pepper and isolate 231 from strawberry showed different virulence for tested host plants.

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Safflower (Carthamus tinctorius L.) is an oil crop that is suitable for dry growing conditions in the Czech Republic. Most of the Czech production is used as bird feed. Typical anthracnose symptoms were observed at one safflower field in the Moravia Region of the Czech Republic during the 2005 growing season. Since then, the disease has become widespread with 100% yield losses observed in several locations in 2009. Symptoms consisted of circular spots on leaves and stem blight characterized by dark-colored stem lesions bearing salmon-colored conidia masses in acervuli. A fungus was isolated from symptomatic safflower plants (cv. Sabina) on potato dextrose agar and incubated at 25°C as described by Kwon et al. (3). The color of fungal colonies changed from white to gray with age with salmon-orange pigmentation on the reverse side of plates. Similar observations had been reported by Jelev et al. (1). Conidia were colorless, fusiform, and measured 10 to 17 μm (mean 13.59) × 4 to 8 μm (mean 5.98). Morphology suggested a Colletotrichum sp. To fulfill Koch' postulates, safflower plants at the BBCH 12 growth stage (second leaf fully expanded) were spray inoculated with a conidia suspension (1 × 105 conidia/ml). Growth chamber conditions were temperature 20 ± 1°C, relative humidity 70 ± 5%, with a 16-h photoperiod. Control plants were treated with sterile distilled water. Typical anthracnose symptoms were observed 1 week after inoculation. Control plants were symptomless. The pathogen was reisolated from infected stems and leaves. PCR with primers CaInt2 and ITS4 was used to confirm the identification of a Colletotrichum sp. Reaction products obtained with these primers were approximately 500 bp long. The ribosomal DNA internal transcribed spacer region containing ITS1, 5.8S, and ITS2 of the isolate from safflower was sequenced and identified with the BLASTn program. The sequence matches with 100% similarity to the sequence of the Glomerella acutata teleomorph of Colletotrichum acutatum (GenBank Accession No. AB548282) and 100% similarity to C. simmondsii (GenBank Accession No. GU183359). C. acutatum and C. simmondsii can be distinguished from each other by pigment color (4), with the safflower isolate matching the description of C. simmondsii. Kim et al. (2) recorded C. acutatum on safflower fields in the Euiseong area of Korea in 1997. To our knowledge, this is the first report of C. simmondsii causing safflower anthracnose in the Czech Republic. References: (1) Z. J. Jelev et al. Plant Dis. 92:172, 2008. (2) W. G. Kim et al. Plant Pathol. J. 15:62, 1999. (3) J. H. Kwon et al. Plant Pathol. J. 15:172, 1999. (4) R. G. Shivas and Y. P. Tan. Fungal Divers. 39:111, 2009.

The differences of air temperature and relative air humidity in wheat, rape and maize canopies at three heights (ground level, effective canopy height and 2 meters above the soil surface), and their comparison with the temperature values of the nearest standard climatological station at the height of 2 meters were studied. The microclimatic data were obtained at the field trial station of the Mendel University in Brno in the Žabčice municipality (South Moravia) in the canopies of winter wheat, winter rape and maize and from the standard climatological station located immediately next to the canopies. It was found, that wheat, rape and maize canopies microclimate differed significantly from those of their surrounding environments. The temperature was usually lower in the ground level and effective height in the wheat and rape stands, air humidity was usually higher in these crops. On the other hand, maize canopies had diverse air temperature values during the studied period.