Browsing by Subject "mycotoxins"

Gibberella zeae (Schwein.) Petch and its asexual form Fusarium graminearum Schwabe is a pathogen of oat, barley, wheat and maize that causes Fusarium head blight in cereals. F. graminearum produces mycotoxins that contaminate yields in humid and warm weather conditions. The pathogen spreads most effectively during its sexual stage. F. graminearum has become more common as a result of climate change and as reduced tillage has become more preferred in cultivation. This research was a part the Fustox Projet in Natural Resources Institute in Jokioinen research station. Develelopment of G.zeae in crop residues was studied. Crop residue samples were collected from no-till and tilled field plots in existing field trials in spring 2013. Occurrence of F. graminearum was studied in barley and oat from no-till and tilled field plots and in oat from a field trial of four tillage methods during the growing season 2013. Efficiency of two fungicides (DMI and DMI+QoI fungicides) were studied in two oat cultivars, barley and spring wheat in MTT Ylistaro research station. Yield samples were also analysed for deoxynivalenol (DON) contamination. Occurrence of the pathogen was determined by incubating straw pieces and kernels in laboratory conditions. Fusarium species were identified by their colony and spore morphology and colour. Contrary to expectations the pathogen was somewhat more prevalent in tilled plots than in reduced tillage. This may be due to greater microbe activity that is capable of decomposing or inhibiting the pathogen in fields with reduced tillage. In this study stem-bases were more infected by the pathogen in reduced tillage. Fungicide treatments were effective in reducing the occurrence of F. graminearum in the field and DON contamination in yield. There were no significant differences between fungicides. The most effective methods of controlling G. zeae and F. graminearum is selection resistant cultivars for cultivation. Careful selection of soil tillage method can also aid in controlling the pathogen.

Oat (Avena sativa L.) is a crop grown for feed and for food industry. It is the most used fodder plant after barley in Finland and is also exported. In 2011, oat was grown on 308 200 hectares in Finland and the average yield per hectare was 3390 kg. Several fungal and virus diseases cause remarkable crop losses in oats. Especially in the temperate zone, the most common disease is the head blight caused by Fusarium species. These fungi overwinter as mycelium or spores and produce mycotoxins. In Finland, F. culmorum is a common DON toxin producer and F. langsethiae is a T-2/HT-2 toxin producer in oats. Toxins affect the quality of oat yield and can make it unsuitable for use. Therefore, the amounts of mycotoxin allowed in cereals are stipulated by food safety authorities. This thesis was a part of MTT Agrifood Research Finland’s Hyötygeeni project. The aim of the research was to study resistance of eight oat cultivars to F. culmorum and F. langsethiae. Indicators of resistance were germination of the infested seeds, the proportion of infected seeds and the amounts of mycotoxins. The trials were made in greenhouse with artificial inoculations. The results indicated that four cultivars expressed similar levels of resistance to both Fusarium species. Three cultivars had better resistance to F. langsethiae than F. culmorum and only one cultivar had better resistance to F. culmorum than F. langsethiae. In future research, the results can be utilized in resistance breeding. Global warming will increase the risk of plant diseases. On that account importance of breeding will be emphasized.