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Using a weather-based model, the G2 Blackspot Manager, the impact of climate change was studied in relation to a major disease of field pea, ascochyta blight, in three different field pea growing locations of Western Australia: Esperance, Lake Grace and Merredin representing high, medium and low rainfall zones. The model was run with weather data for two 30-year periods: the period centering on 1990 (termed as "current climate") and another centering on 2050 (termed as "future climate"). The model outputs were summarised as the epidemic-initiating ascospore-load that crops would be exposed to, disease severity, and yield loss in relation to nine times of sowing within the current sowingwindow of field pea crops in Western Australia. Results show a decreased pressure of ascospore-load across the sowingwindow in all three locations because of changed summer conditions (more rainy days in conjunction with higher temperatures) under future climate, which could be translated as lower disease severity compared to the current climate. The relationship between disease severity and time of sowing showed a significant decrease (P≤0.05) in the intercept of the regression lines for future climate compared to current climate in all three locations, but there was no significant difference between the slopes of the regression lines. This indicated a decreased initial disease pressure for future climate compared to the current. When the impact was assessed in terms of yield loss, results in Lake Grace, in contrast to Esperance and Merredin, showed insignificant difference between current and future climates. This was a consequence of the projected dryfinishing conditions of cropping seasons, the number of which could increase two-fold in the projected future climate. It is concluded that any decrease in ascochyta blight severity as a result of climate change would most likely be location-specific.

This work was done to demonstrate the opportunities provided by application of meta-analysis in plant pathology. It was a case study used to determine the effectiveness of foliar fungicides in minimising yield loss from a complex of yellow spot (Pyrenophora tritici-repentis) and septoria nodorum blotch (Stagonospora nodorum, teleomorph: Phaeosphaeria nodorum) (YS-SNB disease complex) on wheat in the northern grain-belt of Western Australia. Fortyseven datasets of experimental results from 14 growing seasons, using 18 varieties sprayed one to three times, predominantly with tebuconazole or propiconazole fungicides, were analysed. Across the datasets, the wheat yield gain from fungicide application was 297 kg ha −1 with a 95 % confidence interval of 11.6 kg ha −1. Significant yield gains resulted from single or multiple applications of fungicides. Both propiconazole and tebuconazole, increased yield of wheat affected by the YS-SNB disease complex, with yield gain from propiconazole being greater than that from tebuconazole. Yield response varied significantly among crop growing seasons. Meta-analysis was able to aggregate a large number of experimental results and answer important questions related to the variables that influenced those results; in this case the effectiveness of fungicides in minimising yield loss from the YS-SNB disease complex on wheat. It also identified areas where further research needs to be done. It is concluded that meta-analysis has the potential to contribute to similar analyses in other crop disease systems.

G2 Blackspot Manager, the second generation (G2) of Blackspot Manager model, predicts disease severity and yield loss in addition to quantified release of seasonal ascospores in relation to ascochyta blight on field pea. The model predicts the disease severity with respect to the expected exposure of field pea crop to ascospores of D.

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