During the last ten years the cultivation of maize in Sweden has increased and is expected to grow further. Most of the maize in Sweden becomes silage which is used to feed animals at farms. Maize has in other countries been shown to be a substrate for growth of mould and especially Aspergillus spp., Fusarium spp. and Pencillium spp. has been reported. Members of all three of these species can, during favorable conditions, produce mycotoxins which can cause a number of different health problems in both animals and man. The aim of this study was to investigate the occurrence of mould and mycotoxins to increase our knowledge of the hygienic quality of Swedish maize silage. Microbiological analyses were made to study the growth of fungi. To analyze for fumonisin B1, B2 and zearalenone, HPLC with fluorescence detection was made. The mycotoxins mycophenolic acid, roquefortine C, gliotoxin, penicillic acid, penitrem A, fumitremorgen C and verrucologen were analyzed with LC-MS/MS. The results showed that 47 % of the samples were contaminated with Penicillium spp. and 6 % had growth of Aspergillus fumigatus. A small amount of zearalenone was found in one sample and 0.01ppm of roquefortine C was detected in one sample. The data obtained indicate that Swedish maize silage has a moderate growth of fungi with a very low production of mycotoxins. More studies have to be performed to make more decisive conclusions.

Fungi contribute to key processes in the sustainable function of terrestrial ecosystems including nutrient cycling and transport of water to plants. However, some fungal species are of interest because their infection of a susceptible host crop results in diseases negatively affecting food supply and quality. These diseases are expected to be influenced by rotation crops which could impact the development of plant pathogens and their genetic biodiversity. The objectives of this study were to assess the biodiversity of fungal pathogens in durum wheat, to identify the naturally occurring fungi that could have biocontrol potential, and to define the impact of crop rotation with non-cereal crops on fungal populations in durum wheat. For this purpose, in 2004, 2005, and 2006, soil and durum wheat plant samples were collected after preceding crops of <i>Pisum sativum</i> L. (pea), <i>Lens culinaris</i> Medik (lentil), <i>Cicer arietinum</i> L. (chickpea), <i>Brassica napus</i> L. (canola) and <i>Triticum turgidum</i> L. (durum) in a long term experimental site in Swift Current, Sakatchewan. Samples were analyzed using a combination of traditional cultivation techniques and polymerase chain reaction (PCR), sequencing, and denaturing gradient gel electrophoresis (DGGE) techniques. <p>Fusarium species, known as the causal agent of Fusarium head blight (FHB) and Fusarium damaged kernels (FDK) were among the most ubiquitous and abundant in durum tissues. The most prevalent of all Fusarium at the study site were <i>F. avenaceum, F. reticulatum</i>, and <i>F. tricinctum</i>. Other recovered potential fungal pathogens belonged to the genera Bipolaris, Phaeosphaeria, Pyrenophora, Cladosporium, Epicoccum, Alternaria, Cladosporium, Arthrinium, Nigrospora, and Microdochium. Principal component analysis revealed negative correlations between Acremonium, Chaetomium, Penicillium, and pathogenic Fusarium, Bipolaris, Pyrenophora, and Alternaria. These isolates could be antagonistic, and their potential as biocontrol agents against pathogens colonizing durum wheat in the semiarid Saskatchewan should be assessed.<p>Crop rotation had a limited impact on the abundance of fungal pathogens. Fusarium torulosum was less abundant in durum following canola while Bipolaris sorokiniana was less abundant in durum following pea. Even if no single crop rotation reduced significantly the prevalence of F. avenaceum in durum wheat, results suggest that a successful control of this important pathogen requires an integrated approach using diversified rotations.

Fungi contribute to key processes in the sustainable function of terrestrial ecosystems including nutrient cycling and transport of water to plants. However, some fungal species are of interest because their infection of a susceptible host crop results in diseases negatively affecting food supply and quality. These diseases are expected to be influenced by rotation crops which could impact the development of plant pathogens and their genetic biodiversity. The objectives of this study were to assess the biodiversity of fungal pathogens in durum wheat, to identify the naturally occurring fungi that could have biocontrol potential, and to define the impact of crop rotation with non-cereal crops on fungal populations in durum wheat. For this purpose, in 2004, 2005, and 2006, soil and durum wheat plant samples were collected after preceding crops of <i>Pisum sativum</i> L. (pea), <i>Lens culinaris</i> Medik (lentil), <i>Cicer arietinum</i> L. (chickpea), <i>Brassica napus</i> L. (canola) and <i>Triticum turgidum</i> L. (durum) in a long term experimental site in Swift Current, Sakatchewan. Samples were analyzed using a combination of traditional cultivation techniques and polymerase chain reaction (PCR), sequencing, and denaturing gradient gel electrophoresis (DGGE) techniques. <p>Fusarium species, known as the causal agent of Fusarium head blight (FHB) and Fusarium damaged kernels (FDK) were among the most ubiquitous and abundant in durum tissues. The most prevalent of all Fusarium at the study site were <i>F. avenaceum, F. reticulatum</i>, and <i>F. tricinctum</i>. Other recovered potential fungal pathogens belonged to the genera Bipolaris, Phaeosphaeria, Pyrenophora, Cladosporium, Epicoccum, Alternaria, Cladosporium, Arthrinium, Nigrospora, and Microdochium. Principal component analysis revealed negative correlations between Acremonium, Chaetomium, Penicillium, and pathogenic Fusarium, Bipolaris, Pyrenophora, and Alternaria. These isolates could be antagonistic, and their potential as biocontrol agents against pathogens colonizing durum wheat in the semiarid Saskatchewan should be assessed.<p>Crop rotation had a limited impact on the abundance of fungal pathogens. Fusarium torulosum was less abundant in durum following canola while Bipolaris sorokiniana was less abundant in durum following pea. Even if no single crop rotation reduced significantly the prevalence of F. avenaceum in durum wheat, results suggest that a successful control of this important pathogen requires an integrated approach using diversified rotations.

No description available.

Fusarium oxysporum grown on natural media was believed not to produce mycotoxins of the trichothecene family. Using a defined chemical medium toxin production was investigated for and it was found that trichothecenes were produced. A yeast bioassay using Kluyveromyces fragilis, an organiam sensitive to such trichothecenes as T-2 toxin and verrucarin, was used for detection of toxin in culture filtrates. Detectable levels of toxin (0.2 $ mu$g in litre of culture) were seen by day 4 and peaked around day 9 corresponding to maximum growth (measured by mycelial mass). After this time fluctuations in the level of toxin and growth became evident, suggesting a breakdown of the toxins by the organism for a carbon source. Search for an enzyme or enzyme system, capable of degrading T-2 toxin in snail gut enzyme digested F. oxysporum, was attempted using the esterase substrate para-nitrophenol acetate. Esterase activity was detected in all fractions including culture filtrate, soluble protein fraction and insoluble protein fraction, as well as solubilized insoluble proteins (digested by contents of the crude extract). The soluble protein fraction exhibited the highest level of activity. Cells digested with the detergent Lubrol followed by precipitation of the solubilized proteins with ammonium sulphate revealed the presence of an active component(s) in the high molecular weight portion of the soluble cell fraction collected at 50 and 75% saturation. Further purification by DEAE-sepharose failed to produce an active component.

Two fungi that cause disease on onion in the Mid Murray region of South Australia were investigated. These were Fusarium oxysporum f. sp. cepae, the cause of damping off of seedlings, wilting in the field, and basal rot in storage, and Phoma terrestris, which causes pink root. The aim of the study was to investigate resistant or tolerant cultivars and crop rotations as possible management strategies for these diseases. Several Fusarium spp. were isolated from onion roots and bulbs in the field, onion bulbs in storage, soil, and onion seed. All isolates were tested for pathogenicity by various means, however, none caused disease and therefore could not be identified conclusively as F. oxysporum f. sp. cepae. As a result research on Fusarium was discontinued. Pink discolouration was detected on onion roots in commercial crops at Bowhill, South Australia, and isolation of P. terrestris from roots was attempted. Several published and novel methods were employed with variable success. Only one of the published methods yielded P. terrestris, but results were inconsistent. Two methods developed in this study permitted isolation of P. terrestris. In both cases, infested plant material was incubated on wheat straw agar (WSA), which turns pink in the presence of P. terrestris. One method involved soaking surface sterilised pink-pigmented wheat straw in solution, at approximately 24ºC for 2 days, and then spreading 1 ml of the resulting suspension on acidified potato dextrose agar (APDA) and incubating for a further 7 to 10 days. The second method involved dispensing warm sterile water into a plate of pink-pigmented WSA, agitating the plate, and spreading 1 ml aliquots onto APDA, and incubating for 7 to 10 days. One isolate of P. terrestris, shown to be pathogenic to onion was used in subsequent experiments. Several brown onion cultivars commonly grown in the Mid Murray region of South Australia, or marketed as tolerant to pink root, were examined for susceptibility to infection by P. terrestris. Seven cultivars were tested in vitro, and seedlings of eight cultivars were grown in a greenhouse for 4 months in soil naturally infested with P. terrestris. Selected cultivars were also evaluated in the field. Of the cultivars tested, none was significantly less susceptible to infection by P. terrestris than any other as indicated by pink pigment on WSA. Cereals such as wheat, oat and barley, as well as lucerne and canola, are grown in rotation with onion to provide ground cover, to minimise soil erosion and reduce inoculum of pathogens between onion crops. As the susceptibility of these rotation crops to P. terrestris was not known, several were tested in the field and in the greenhouse for their ability to act as hosts for P. terrestris. Likewise, the potential of weeds commonly found in onion fields to act as hosts of P. terrestris was investigated. Less P. terrestris was detected in the roots of plants of oat cultivars Marloo and Swan, as well as barley cultivars Galleon and Schooner than of most other crops tested and, thus, these cvs were considered less likely to act as hosts of P. terrestris. Weeds such as Brassica tournefortii, Portulaca oleracea and Oxalis pes-caprae collected from the field were infected by P. terrestris, whereas P. terrestris was not detected in the roots of Chenopodium album. In summary, new methods for isolation of P. terrestris were identified and may, with further development, aid in research on pink root. The onion cultivars tested in this study did not differ in susceptibility to pink root, but more cultivars should be tested. P. terrestris infected a range of other crops and weeds, and it is recommended that further work is conducted in this area to facilitate cultural management of onion crops to minimise build up of inoculum in the soil. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1473377 / Thesis (M.Ag.Sc.) -- University of Adelaide, School of Agriculture, Food and Wine, 2009

Proefschrift Universiteit van Amsterdam. / Met lit. opg. - Met samenvatting in het Nederlands.

Presented as Thesis (Ph. D.)--University of Wisconsin--Madison, 1920. / Title from added collective thesis title page. Reprinted from American journal of botany. Part 1: vol. 10, no. 2 (Feb. 1923), Part 2: vol. 10, no. 3 (Mar. 1923). eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1969. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1930. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 52-53).