Methods for assessment of light leaf spot (Pyrenopeziza brassicae) on winter oilseed rape (Brassica napus) in the UK

Light leaf spot (Pyrenopeziza brassicae) was assessed as % plants with light leaf spot, % leaves with light leaf spot or % leaf area with light leaf spot in winter oilseed rape field experiments done at different sites (Rothamsted, Hertfordshire; Boxworth, Cambridgeshire; near Aberdeen, Scotland), with different cultivars (e.g. Bristol and Capitol), different fungicide treatments, on plants sampled at different dates. Regression analyses on data from these experiments showed that there were consistently good relationships between % leaves with light leaf spot and % plants with light leaf spot for plants sampled during the autumn and winter, until the % plants with light leaf spot approached 100%. The slopes and positions of regression lines were sometimes affected by cultivar, fungicide treatment or sampling date, but not by site. The relationship between % leaf area with light leaf spot (square root-transformed) and % leaves with light leaf spot was less consistent than that between % leaves with light leaf spot and % plants with light leaf spot and was sometimes affected by cultivar, fungicide treatment or sampling date but not by site. The relationship between % leaf area with light leaf spot (square root-transformed) and % plants with light leaf spot was also inconsistent and was sometimes affected by cultivar, fungicide treatment, sampling date and site.     

A blueprint for the countryside

Much of the UK (and some of Western Europe) consists of ancient farmland and thus conservation effort is concentrated on maintaining intermediate levels of intervention. Conservation therefore differs markedly from that in much of the rest of the world. The future of farmland birds depends upon the success of agri-environment schemes and the changes in agriculture resulting from the development of new technologies. The experience of agri-environment schemes shows that they have patchy success. An alternative approach is to align conservation with the other external benefits to society of natural and semi-natural landscapes, such as health, flood protection, water purification and tourism and then restore natural ecosystems. Many of the biodiversity objectives are then produced while achieving other objectives and reducing expenditure. Within this framework it may also be possible, based on use of Vera's interpretation of landscape history, to create a few areas of natural ecosystem functioning. The expected future changes in EU agricultural support could provide the opportunity to achieve this.