The relationship between weather conditions and most important economi-cally infectious diseases of assimilative apparatus of forest trees was investigated for stands up to 20 years old. The analyses were based on data of Scots pine needle cast, twisting rust, shoot dieback, oak powdery mildew occurrence in Poland from the years 1975-2004 and meteorological data from 30 stations located all over the country from the years 1966-2005. There were 130 meteorological parameters of air and soil temperature, precipitation, humidity, synthetic hydrothermal coefficients (in forms of monthly, seasonal, annual and multi-annual means) as well as their deviations from multi-annual averages used in the calculations. To determine most influential for disease occurrence weather variables correlation and principal component analyses were applied, while multiple regression analysis was used to determine the dependence between diseases occurrence and selected weather parameters. For all analyzed diseases statistically significant dependence was found, most pronounced for meteorological parameters of the year of disease appearance as well as from one-two years earlier.
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The aim of the study was the estimation of six mixtures for renovation of pastures located on the soils of V and VI quality class under differentiated nitrogen fertilization. The experiment was carried out in the farm specializing in breeding Limousin beef cattle in the years 2008-2012. The most important factor verifying the suitability of mixtures has proved the botanical stability and the resistance to weed infestation of plant communities created by these mixtures. These features were guaranteed by the multispecies mixtures of cocksfoot, but turned out to be completely unreliable in case of mixture with dominance of tall fescue. Cocksfoot was the most dynamic species of the communities of pasture. This species was increasing its percentage in the subsequent years of utilization, effectively reducing their weed infestation. Valuable component of mixtures has also proved the perennial ryegrass which was persisting in significant quantities during the four years. Its significant share in mixtures without cocksfoot grass turned out to be far less competitive with respect to the developing dicotyledonous weed species. Also the amount of cocksfoot negatively affect the development of perennial ryegrass, especially at higher levels of nitrogen fertilization. The dose of 120 kg of nitrogen, used together ...
