Study of Fusarium Langsethiae infection in UK cereals

Opoku, N. (2012) Study of Fusarium Langsethiae infection in UK cereals. Doctoral thesis, Harper Adams University.

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Abstract

Fusarium langsethiae is a relatively newly identified Fusarium species. It is responsible for the high levels of the Fusarium mycotoxins HT-2 and T-2 in oats in the UK and other parts of Europe. A field survey was performed to study the infection and development of F. langsethiae in the growing season of cereals under commercial production (2009 – 2011). The data showed oats to contain the highest levels of both F. langsethiae biomass and HT-2+T-2 mycotoxins in harvested heads of the cereals studied. Head infection if it occurs, was at emergence but before flowering, a deviation from other Fusarium species. Seemingly symptomless heads had high levels of F. langsethiae DNA and HT-2+T-2, confirming previous suggestions that F. langsethiae is a symptomless pathogen of oats. Four field experiments where winter and spring varieties of wheat, barley and oats were cultivated under identical field and agronomic conditions at two sites again showed oats to have the highest F. langsethiae DNA and HT-2+T-2 concentration among the cereals studied. Interestingly, there was a significantly higher quantity of HT-2+T-2 per unit of F. langsethiae DNA for oats compared to wheat and barley. An in-vitro detached leaf assay was used to screen UK varieties from the HGCA Recommended Lists in 2010 of wheat, barley and oats for resistance against F. langsethiae infection. Results from the experiment showed that none of the cereal varieties screened had total resistance to F. langsethiae infection, however, in oats, varieties with low HT-2+T-2 in heads under field conditions also had shorter lesion lengths in-vitro suggesting that the detached in-vitro leaf assay could be a good predictor of HT-2+T-2 concentration in harvested grain. Data from four different artificial inoculation methods (seed assay, stem base infection, boot-inoculation and a spray inoculation) established that although F. langsethiae is a seed borne pathogen it was not systemically transmitted from the seed to the other plant parts. The stem base infection study showed that F. langsethiae did not cause any stem base infection even when in close contact with the stem. The spray inoculation resulted in cereal heads having F. langsethiae DNA concentrations and subsequent HT-2+T-2 levels comparable to what has been observed under natural infections in commercial fields, suggesting that the infection route for F. langsethiae may not be that different from the other Fusarium head blight pathogens. Based on all the experiments carried out in this thesis, a generalized life-cycle was hypothesized for F. langsethiae which deviates from that of the other Fusarium species on small grain cereals due to its early head infection and its inability to cause stem base infection.

Item Type: Thesis (Doctoral)
Divisions: Crop and Environment Sciences
Depositing User: Ms Kath Osborn
Date Deposited: 21 Aug 2018 15:30
Last Modified: 31 Aug 2018 14:33
URI: http://hau.repository.guildhe.ac.uk/id/eprint/17312

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