Interdisciplinary assessment of the potential for improving Integrated Pest Management practice in Scottish spring barley
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Date
09/07/2018Author
Stetkiewicz, Stacia Serreze
Metadata
Abstract
Integrated Pest Management (IPM) has long been promoted as a means of reducing
reliance on pesticide inputs as compared to conventional farming systems. Reduced
pesticide application could be beneficial due to the links between intensive pesticide use and
negative impacts upon biodiversity and human health as well as the development of
pesticide resistance. Work assessing the potential of IPM in cereal production is currently
limited, however, and previous findings have generally covered the subject from the
perspective of either field trial data or social science studies of farmer behaviour. This thesis
attempts to help to address this knowledge gap by providing a more holistic assessment of
IPM in Scottish spring barley production (selected because of its dominance in Scotland’s
arable production systems), in relation to three of its most damaging fungal pathogens:
Rhynchosporium commune, Blumeria graminis f.sp. hordei, and Ramularia collo-cygni. Several
IPM techniques of potential relevance to the sector were identified, and the prospects of
three in particular – crop rotation, varietal disease resistance, and forecasting disease
pressure – were assessed in several ways.
Preliminary analysis of experimental field trial data collected from 2011 – 2014 across
Scotland found that the majority of spring barley trials in this period (65%) did not show a
statistically significant impact of fungicide treatment on yield, with the average yield
increase due to fungicide application being 0.62 t/ha. This initial analysis was expanded
upon using stepwise regressions of long-term (1996 – 2014) field trial data from the same
dataset. Here, the difference between treated and untreated yields could be explained by
disease resistance, average seasonal rainfall (whereby wetter seasons saw an increased
impact of fungicide use on yield), and high combined disease severity.
Stakeholder surveying provided information about current practice and attitudes
towards the selected IPM techniques amongst a group of 43 Scottish spring barley farmers
and 36 agronomists. Stakeholders were broadly open to taking up IPM measures on farm;
sowing of disease resistant varieties was most frequently selected as the best technique in
terms of both practicality and cost, though individual preference varied. However, a
disparity was seen between farmer perception of their uptake of IPM and actual, self-reported
uptake for both varietal disease resistance and rotation. Farmers and agronomists
also overestimated the impact of fungicide use as compared with the field trials results – the
majority of stakeholders believed fungicide treatment to increase yields by 1 - 2 t/ha, while
the majority of 2011 – 2014 field trials had a yield difference of under 1 t/ha. The reasons
behind these differences between perception and practice are not currently known.
Finally, an annual survey of commercial crops, gathered from 552 farms across
Scotland (from 2009 – 2015), highlighted two gaps where IPM practice could be improved
upon. Firstly, relatively few of the varieties listed in the commercial crops database were
highly resistant to the three diseases – 26.1% were highly resistant to Ramularia, 14.2% to
Rhynchosporium, and 58.1% to mildew. Secondly, 71% of the farms included in the
database had planted barley in at least two consecutive seasons, indicating that crop rotation
practices could be improved.
The overarching finding of this project is that there is scope for IPM uptake to be
improved upon and fungicide use to be reduced while maintaining high levels of yield in
Scottish spring barley production. Incorporating experimental field data, stakeholder
surveying, and commercial practice data offered a unique view into the potential for IPM in
this sector, and provided insights which could not have been gained through the lens of a
single discipline.