The UK risk assessment scheme for all non-native species

1. A pest risk assessment scheme, adapted from the EPPO (European and Mediterranean Plant Protection Organisation) scheme, was developed to assess the risks posed to UK species, habitats and ecosystems by non-native taxa. 2. The scheme provides a structured framework for evaluating the potential for non-native organisms, whether intentional or unintentional introductions, to enter, establish, spread and cause significant impacts in all or part of the UK. Specialist modules permit the relative importance of entry pathways, the vulnerability of receptors and the consequences of policies to be assessed and appropriate risk management options to be selected. Spreadsheets for summarising the level of risk and uncertainty, invasive attributes and economic impact were created. In addition, new methods for quantifying economic impact and summarising risk and uncertainty were explored. 3. Although designed for the UK, the scheme can readily be applied elsewhere

Oilseed rape : disease development, forecasting and yield loss relationships

A series of fourteen replicated plot scale experiments was established between 1991 and 1994 to determine the effect of disease on the yield of winter oilseed rape and the economic threshold and optimum fungicide timings for disease control. The cultivar Envol was selected for use throughout the experiment as it was a popular cultivar and was moderately susceptible to both canker and light leaf spo

Yield loss of winter oilseed rape in relation to severity of stem canker (Leptosphaeria maculans ) in the UK

The relationships between yield loss and incidence or severity of stem canker in winter oilseed rape were analysed using data from experiments at Rothamsted in 1991/92, Withington in 1992/93, Boxworth in 1993/94 and Rothamsted in 1997/98. Critical point models and area under disease progress curve (AUDPC) models were better than multiple point models for describing relationships between yield (t ha-1) and incidence or severity of stem canker. Since yield in t ha-1 is influenced by many factors other than disease, % yield loss was calculated. Critical point models and AUDPC models relating % yield loss to stem canker were constructed and models for different experiments were compared. A critical point model relating % yield loss to stem canker incidence (GS 6.3-6.4), and AUDPC models for incidence or severity from growth stages 4.8 to 6.4 were derived from the combined data sets for the three experiments. The relationships between % yield loss and % plants with different stem canker severity scores at different growth stages, and between % yield loss and incidence or severity of both basal stem cankers and upper stem lesions were also analysedNon peer reviewe

Effects of severity and timing of stem canker (Leptosphaeria maculans) symptoms on yield of winter oilseed rape (Brassica napus) in the UK

The relationships between yield loss and incidence (% plants with stems affected) or severity (mean stem score, 0-4 scale) of stem canker in winter oilseed rape were analysed using data from experiments at Rothamsted in 1991/92, Withington in 1992/93, Boxworth in 1993/94 and Rothamsted in 1997/98. Critical point models and area under disease progress curve (AUDPC) models were better than multiple point models for describing relationships between yield (t ha(-1)) and incidence or severity of stem canker for the four experiments. Since yield is influenced by many factors other than disease, % yield loss was calculated and critical point models and AUDPC models relating % yield loss to stem canker were constructed. The critical point models for % yield loss on stem canker incidence for three of the four experiments were similar, but differed from that for Rothamsted in 1991/92. There were also no differences between models of % yield loss on AUDPC of both incidence and severity for these three experiments. Therefore, general models of % yield loss (L) against AUDPC of incidence (X) or severity (S) of stem canker from growth stages 4.8 to 6.4 were derived from the combined data sets for the three experiments: L = -0.76 + 0.0075X (R-2 = 35%, p < 0.001), L = 0.26 + 0.53S (R-2 = 37%, p < 0.001). The relationships between % yield loss and % plants with different stem canker severity scores at different growth stages were also analysed; the greatest yield losses were generally associated with the largest severity scores, for plants assessed at the same crop growth stage, and were also associated with the early development of stem lesions. Further analyses showed that % yield loss was related to incidence or severity of both basal stem cankers and upper stem lesions in experiments at Boxworth in 1993/94 and at Rothamsted in 1997/98.Peer reviewe