Environmental factors, including weather and soil conditions, can affect the competitive effects of weeds on crops. This work aimed at a comparison of the competitive abilities of winter wheat toward bentgrass (Apera spica-venti (L.) P. Beauv) with single herbicide resistance, multiple herbicide resistance, or a susceptible biotype in different environmental conditions of Poland. A replacement series competition model was applied in field conditions in 2017–2018 and 2018–2019 across the country. A competitive ratio (CR) was calculated for the relative biomass of plants and grain number. A canonical variate analysis (CVA) was performed for biological parameters and a day-difference in emergence between winter wheat and bentgrass with the hydrothermal coefficient and soil texture in all of the sites in each season separately. Winter wheat emergence was correlated with the amount of precipitation after seeding, and was fastest for five days in humid conditions, and slowest up to 22 days, when the precipitation in October was low. The CVA proved that winter wheat’s competitive effects toward the susceptible or herbicide-resistant biotypes of bentgrass are site-specific. During the dry season, the bentgrass biotype with multiple herbicide resistance was more competitive toward winter wheat than the susceptible one. The wheat CR < 1 with regard to biomass and both biomass and the grain number was in 64% and 50% of all the combinations with the resistant biotype. In conclusion, weather affects the competitive effects of winter wheat toward herbicide-susceptible or resistant bentgrass.

The results of the studies carried out over the last 50 years have not provided a clear answer to questions concerning the interaction between Clavibacter sepedonicus (Cs), potato and the environment. The reason is insufficient knowledge of the biology of the causal agent of ring rot, problems of research methodology and the influence of many environmental and biotic factors on the degree of plant infestation. The research conducted in the years 2013–2016 in the Plant Breeding and Acclimatization Institute – National Research Institute concerned the determination of the influence of weather conditions, involved the influence of temperature and Sielianinov hydrothermal coefficient on the development of Cs bacteria in stems and progeny tubers, as well as the occurrence of disease symptoms on plants and in tubers of eight potato varieties. It was found that genotype had the greatest impact on leaf and tuber infestation, while weather conditions were less significant. The results of correlation analysis indicate that the weight of tubers of plants infected by Cs increased statistically significantly with increases in air and soil temperature. On the other hand, air and soil temperature in the initial vegetation period did not significantly affect the number of potato plant tubers infested by Cs. In a 4-year experiment, it was not shown how air and soil temperature and the Sielianinov hydrothermal coefficient affected the degree of potato leaf and tuber infestation. In most cases, potato infestation by Cs caused a decrease in yield.

The aim of this study was to determine the response of potato cultivars to Clavibacter sepedonicus (Cs) infection in a field experiment. The research focused on the infection in a latent form as it is a risk for unnoticed spread. A total of 18 cultivars were tested in the years 2013–2016. Symptoms of the disease were observed on the leaves during growth and in tubers after harvest and after storage. The infection incidence was determined by microscopic observation of leaf and tuber samples stained by the IFAS method. A diverse response of potato cultivars to Cs infection was found. The lowest number of asymptomatic infected plants was found in cultivars ‘Vineta’, ‘Bila’ and ‘Irga’. As for cultivar ‘Stasia’, the entire tuber yield was latently infected by Cs. A low or medium concentration of Cs cells in leaves did not change significantly or increased depending on the potato cultivar. A higher incidence of tubers with disease symptoms was found after the storage period. In eight of the cultivars tested, the level of tuber infection by Cs confirmed microscopically after harvest was significantly correlated with the occurrence of disease symptoms in tubers after the storage period.

Mątwik ziemniaczany i mątwik agresywny to dwa nicienie tworzące cysty na korzeniach ziemniaka. Zarówno w Polsce jak i w wielu innych państwach posiadają status organizmów kwarantannowych. Obecność mątwika ziemniaczanego może powodować straty w plonie bulw sięgające 50–80%. Metody zwalczania mątwika można podzielić na trzy grupy: agrotechniczną, biologiczną i chemiczną. Pozyskane wyniki będą stanowiły podstawę opracowania zaleceń dla rolników, które usprawnią eliminację szkodnika.