This is the report from a BSPP MSc/MRes Bursary.
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In 2019, the European Union was forced to introduce more stringent legislation (Regulation 2019/1381) because the general population had been demanding a ban on glyphosate herbicides, advocating for a healthier environment and for better overall human health. This represented the culmination of a process that commenced in 1993, when the EU launched a review of all active ingredients used in agriculture to determine the ones that posed a risk to the environment, especially groundwater and non-target organisms, with the goal to limit their widespread use. However, in the years 2000-2019, the use of global pesticides has increased by 36% to around 4.2 million tonnes, reaching a plateau after 2012; in the year 2018, 350,000 tonnes of pesticides were bought in the EU alone. These are very high numbers and they give a clear indication of the central role that plant protection products (PPPs) continue to play in pest management programmes.
Research has amply shown that, without the use of PPPs, plant health cannot be achieved. Further loss of synthetic fungicides to the European market as a result of the tightening nature of the new legislation will severely restrict the ability to control plant diseases in the future. So far, the strategies implemented in pesticide-free integrated pest management programmes, especially for cereals, have failed to show a similar level of disease control when compared to synthetic fungicides. This is mainly because pathogens have been able to adapt to the host resistance, even when new resistant varieties have been introduced in the market and the genetic resources that can be used in plant breeding programmes are fairly limited. Additionally, plant protection products and their active ingredients can be considered some of the safest products worldwide because they are the most studied and comprehensively risk assessed marketable products on a global scale.
Bayer CropScience Limited has sponsored a 5 year study to be carried out at Harper Adams University to determine the level of plant health achievable without the use of seed treatments. The plants used for this study have been wheat and barley due to their importance as key staple crops. The most destructive seed-borne diseases that affect these plants are represented by Fusarium seedling blight, which is caused by Fusarium and Microdochium spp., bunt caused by Tilletia caries and smuts caused by Ustilago spp. Considering that this is an ongoing study, I was only involved in the first stage of this project hence my results cannot in any way be considered exhaustive or definitive.
An experiment was conducted to identify the impact of using farm-saved seed compared to certified seed, both with and without a seed treatment, on seedborne diseases of wheat and barley. This is the first year of a long-term study that will evaluate the impact over five years. The experiment was carried out in two different fields using two cultivars of wheat (KWS Extase and KWS Basset) and one of barley (Cassata). The fungicide seed treatment used comprised of Redigo Pro and Raxil Star, whose active ingredients belong to the classes of triazoles and phenylamide fungicides. The visual disease assessments were performed in two occasions, at GS 32, when the plant stem commences to elongate and at GS 77, during the grain-filling phase. It was found that only the untreated certified seeds of wheat cv KWS Extase showed to be affected by a lack of treatment and this was only found in one field at GS 32. Apart from this notable exception, no significant interactions between fungicide seed treatment and number of plants per square metre and incidence of Fusarium seedling blight were observed. Farm-saved untreated KWS Basset wheat seeds, additionally, were found to show an average of 189 bunt spores (Tilletia caries) by laboratory tests. However, this fungus was too difficult to detect with the naked eye hence it was not further investigated at this stage of the experiment. Plots from farm-saved seeds of barley, additionally, showed a very low incidence of loose smut at GS 77, with an average of disease index of 0.12%. This experiment is part of a five year long-term project and overall conclusions cannot be drawn at this stage; however, it would appear that, at least in the case of the wheat cultivar KWS Extase, the use of a fungicide seed treatment was beneficial. It will be interesting to see the development of seedborne pathogens overtime as saved seed from the previous experiment is subsequently sown each year.
My gratitude goes to BSPP for kindly having financially supported my studies at Harper Adams University with a significant bursary as well as my supervisor Professor Simon Edwards and Bayer CropScience Limited for sponsoring the field experiments.
Patrizio Orru
This is the report from a BSPP MSc/MRes Bursary.
Click here to read more/apply for one yourself.
