One of a possible way to reduce chemical control of weeds are mycoherbicides. In 2008 and 2009 the research was carried out on the occurrence of weed diseases growing on selected sites of meadows in Warta valley and in Poznań (fallows, weeded lawns). On weeds powdery mildews and rusts occurred commonly. Powdery mildews were found on plants belonging to families of Asteraceae, Fabaceae, Brassicaceae, Convolvulaceae, Lamiaceae, Urticaceae, Poaceae, whilst rusts symptoms occurred on Senecio vulgaris and Cirsium arvense. Other disease symptoms – leaf and stem spot, black leg, root rot were also observed. Fungi of genus Alternaria, Fusarium, Cercospora, as well as nonsporulating colonies, were isolated from infected leaves. Spots on stems, stem bases and root rots were caused by Fusarium sp. and Sclerotinia sclerotiorum.
The investigations were carried within the meadow agrocenoses, located in the valley of the Warta Landscape Park, between Dolany and Ląd. Different disease symptoms occurring on plant organs of Cirsium arvense such as leaves, shoots and roots were recorded. Dying of inflorescences and infructescences and sometimes dying of the whole plant, as well as damages caused by pests were also observed. Alternaria spp., Epicoccum spp. and Fusarium spp. were the most isolated species from spots, shoots and infructesences. Coniothyrium and Epicoccum were also often isolated from leaves while Acremonium, Phomopsis, Phoma and Sclerotinia sclerotiorum were cultured from the basis of shoots and roots. It was determined that plants of C. arvense were sick on all observed sites, however disease severity depended on location and age of the plants. Lower pathogen infections of C. arvense were detected within populations with majority of young plants. In July and August powdery mildew (Oidium spp.) and rust (Puccinia punctiformis) were dominating on them, while in the older populations leaf spot diseases and dying of inflorescences and infructescences were observed. Pathogens of C. arvense were considered as potential active substances of bioherbicides.
The ecophysiological regulation of seed dormancy in perennial species and those with a varied life cycle has not been studied in detail yet. That is why an attempt has been made to determine the Cirsium arvense seed water relations during stratification and afterripening at different temperatures and germination at constant or fluctuating temperatures on the basis of the hydrotime model. The obtained results showed that breaking of the primary dormancy of achenes took place only during the first stratification month at moderate temperatures, mainly due to an increase in the average water-stress tolerance in a seed population. The induction of secondary seed dormancy during after-ripening at all temperatures resulted mostly from a substantial loss of the seeds' ability to tolerate water stress. Fluctuating temperatures affected neither seed germination nor the hydrotime model parameters. The analysis of the variations of hydrotime model parameters allows a better understanding of the physiological basis of seed dormancy relief and induction.
This paper presents the results of a research on the variability of Orobanche pallidiflora Wimm. et Grab. specimens which grew in an abandoned meadow in Lubiatowo (Pyrzyce County, West Pomeranian Voivodeship). Their spatial distribution was investigated and some biometric measurements were taken (shoot height, stem height, stem basal width, number of leaves, length of inflorescence, and number of flowers). Also participation of the species in plant communities was examined. 75 individuals of Orobanche pallidiflora were recorded in the sampling plot of 100 m². Their distribution was clustered. The majority of the biometric measures had low coefficient of variation values, except for the number of flowers (V = 59.63%). The specimens grew in species-poor Molinietalia communities of the Molinio-Arrhenatheretea class, where Cirsium oleraceum and Cirsium arvense were the dominant species.
Simultaneous identification of eight phenolic acids (gallic, protocatechuic, chlorogenic, p-hydroxybenzoic, vanillic, caffeic, p-coumaric and ferulic) and three flavonoid aglycones (Iuteolin, kaempferol and apigenin) in Et20-fractions of inflorescences and leaves of five species of Cirsium genus - C. arvense, C. oleraceum, C. palustre, C. rivulare and C. vulgare was carried out by HPLC method. Phenolic acids and flavonoids were analyzed also in terms of quantity. The contents of phenolic acids, expressed as cafifeic acid, determined by the spectroscopic method with Arnov's reagent, were higher in leaves than in flower heads of all investigated species and amounted from 0.15% in C. vulgare inflorescences to 1.31% in C. palustre leaves. The flavonoid contents, indicated by Christ-Miiller's method ranged from 16 mg • 100g1 per dry source in C. arvense and C. palustre inflorescences to 70 mg • 100g ' in C. oleroceum Leaves.
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