Angela M. Berrie

Epidemiology of mycotoxigenic fungi associated with Fusarium ear blight and apple blue mould: A review

Research on the epidemiology of plant diseases is briefly reviewed, focusing on two diseases caused by mycotoxin–producing pathogens: Fusarium ear (or head) blight (FEB or FHB) of small grain cereals and apple blue mould (Penicillium expansum). Pathogen development during its key life cycles is discussed in relation to important environmental factors and host resistance. Current control methods are also reviewed, focusing on cultural and biological methods. The future challenge is to understand the relationships between disease severity, fungal biomass and the production of associated mycotoxins in order to minimize risks of both disease damage to crop yields and threat to human health posed by mycotoxins.

Modeling Infection of Strawberry Flowers by Botrytis cinerea Using Field Data

ABSTRACT The incidence of strawberry flower infection by Botrytis cinerea was monitored in unsprayed field plots in three successive years together with meteorological data and numbers of conidia in the air. There were large differences in conidia numbers and weather conditions in the 3 years. Three sets of models were derived to relate inoculum and weather conditions to the incidence of flower infection; by inoculum only, by weather variables only, and by both inoculum and weather variables. All the models fitted the observed incidence satisfactorily. High inoculum led to more infection. Models using weather variables only gave more accurate predictions than models using inoculum only. Models using both weather variables and inoculum gave the best predictions, but the improvement over the models based on weather variables only was small. The relationship between incidence of flower infection and inoculum and weather variables was generally consistent between years. Of the weather variables examined, daytime vapor pressure deficit and nighttime temperature had the greatest effect in determining daily incidence of flower infection. Infection was favored by low day vapor pressure deficit and high night temperature. The accuracy and consistency of the weather-based models suggest they could be explored to assist in management of gray mold.

Within‐ and between‐orchard variability in the sensitivity of Venturia inaequalis to myclobutanil, a DMI fungicide, in the UK

BACKGROUND Myclobutanil, a demethylation inhibitor (DMI) fungicide, is an important fungicide for controlling apple scab and powdery mildew. Overuse of this fungicide has led to establishment of scab isolates with reduced sensitivity to this fungicide in several countries. Experiments were conducted to determine the sensitivity of the causal agent of apple scab, Venturia inaequalis (Cooke) Winter, to myclobutanil in the UK, in order to assess whether there is a relationship between fungal insensitivity and the number of DMI applications, and establishing whether fungal sensitivity varied greatly within an orchard. RESULTS Reduced sensitivity of V. inaequalis to myclobutanil was positively related linearly to the number of DMI applications. ED(50) values ranged from 0.028 to 1.017 mg L(-1) (average = 0.292) for the baseline population, whereas isolates from two other orchards had much greater ED(50) values, ranging from 0.085 to 5.213 mg L(-1) (average = 1.852). There was significant variation in fungal sensitivity to myclobutanil among fungal isolates from different locations within a single orchard. CONCLUSIONS Spatial spread of insensitive isolates of V. inaequalis to myclobutanil is likely to be limited in distance. Conidia may be an important source of primary inoculum. Myclobutanil should still be effective for most field isolates, but its use should be strategically integrated with other groups of fungicides.