ADAS High Mowthorpe

Malton, United Kingdom

ADAS High Mowthorpe

Malton, United Kingdom
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Jorgensen L.N.,University of Aarhus | Van Den Bosch F.,Rothamsted Research | Oliver R.P.,Curtin University Australia | Heick T.M.,University of Aarhus | Paveley N.D.,ADAS High Mowthorpe
Annual Review of Phytopathology | Year: 2017

Fungicides should be used to the extent required to minimize economic costs of disease in a given field in a given season. The maximum number of treatments and maximum dose per treatment are set by fungicide manufacturers and regulators at a level that provides effective control under high disease pressure. Lower doses are economically optimal under low or moderate disease pressure, or where other control measures such as resistant cultivars constrain epidemics. Farmers in many countries often apply reduced doses, although they may still apply higher doses than the optimum to insure against losses in high disease seasons. Evidence supports reducing the number of treatments and reducing the applied dose to slow the evolution of fungicide resistance. The continuing research challenge is to improve prediction of future disease damage and account for the combined effect of integrated control measures to estimate the optimum number of treatments and the optimum dose needed to minimize economic costs. The theory for optimizing dose is well developed but requires translation into decision tools because the current basis for farmers' dose decisions is unclear. © 2017 by Annual Reviews. All rights reserved.


Foulkes M.J.,University of Nottingham | Slafer G.A.,University of Lleida | Davies W.J.,Lancaster University | Berry P.M.,ADAS High Mowthorpe | And 6 more authors.
Journal of Experimental Botany | Year: 2011

A substantial increase in grain yield potential is required, along with better use of water and fertilizer, to ensure food security and environmental protection in future decades. For improvements in photosynthetic capacity to result in additional wheat yield, extra assimilates must be partitioned to developing spikes and grains and/or potential grain weight increased to accommodate the extra assimilates. At the same time, improvement in dry matter partitioning to spikes should ensure that it does not increase stem or root lodging. It is therefore crucial that improvements in structural and reproductive aspects of growth accompany increases in photosynthesis to enhance the net agronomic benefits of genetic modifications. In this article, six complementary approaches are proposed, namely: (i) optimizing developmental pattern to maximize spike fertility and grain number, (ii) optimizing spike growth to maximize grain number and dry matter harvest index, (iii) improving spike fertility through desensitizing floret abortion to environmental cues, (iv) improving potential grain size and grain filling, and (v) improving lodging resistance. Since many of the traits tackled in these approaches interact strongly, an integrative modelling approach is also proposed, to (vi) identify any trade-offs between key traits, hence to define target ideotypes in quantitative terms. The potential for genetic dissection of key traits via quantitative trait loci analysis is discussed for the efficient deployment of existing variation in breeding programmes. These proposals should maximize returns in food production from investments in increased crop biomass by increasing spike fertility, grain number per unit area and harvest index whilst optimizing the trade-offs with potential grain weight and lodging resistance. © 2010 The Author(s).


Helps J.C.,Rothamtsed Research | Paveley N.D.,ADAS High Mowthorpe | van den Bosch F.,Rothamtsed Research
Journal of Theoretical Biology | Year: 2017

Insect management strategies for agricultural crop pests must reduce selection for insecticide resistant mutants while providing effective control of the insect pest. One management strategy that has long been advocated is the application of insecticides at the maximum permitted dose. This has been found, under some circumstances, to be able to prevent the resistance allele frequency from increasing. However this approach may, under different circumstances, lead to rapid selection for resistance to the insecticide. To test when a high dose would be an effective resistance management strategy, we present a flexible deterministic model of a population of an insect pest of agricultural crops. The model includes several possible life-history traits including sexual or asexual reproduction, diploid or haplodiploid genetics, univoltine or multivoltine life cycle, so that the high dose strategy can be tested for many different insect pests. Using this model we aim to identify the key characteristics of pests that make either a high dose or a low dose of insecticide optimal for resistance management. Two outputs are explored: firstly whether the frequency of the resistance allele increases over time or remains low indefinitely; and secondly whether lowering the dose of insecticide applied reduces or increases the rate of selection for the resistance allele. It is demonstrated that with high immigration resistance can be suppressed. This suppression however, is rarely lost if the insecticide dose is reduced, and is absent altogether when individuals move from the treated population back into an untreated population. Reducing the dose of insecticide often resulted in slower development of resistance, except where the population combined a high influx of less resistant individuals into the treated population, a recessive resistance gene and a high efficacy, in which case reducing the dose of insecticide could result in faster selection for resistance. © 2017


Berry P.M.,ADAS High Mowthorpe | Kindred D.R.,ADAS Boxworth | Olesen J.E.,University of Aarhus | Jorgensen L.N.,University of Aarhus | Paveley N.D.,ADAS High Mowthorpe
Plant Pathology | Year: 2010

A method for calculating the effect of disease control on greenhouse gas (GHG) emissions associated with wheat production, reported previously, was developed further to account for effects of disease control on the amount of fertilizer nitrogen (N) which should be applied and on changes in land use. Data from nine randomized and replicated field experiments from the UK and Denmark showed that the economic optimum N input to winter wheat was greater if diseases were controlled by fungicides, than for untreated wheat. The GHGs associated with this additional N largely negated the benefit to emissions per tonne of grain resulting from disease control. However, the mean grain yield obtained without fungicide treatment was 6·71 t ha-1, compared to 8·88 t ha-1 with fungicide treatment, if N input was optimal for each situation. In the absence of disease control by fungicides, and assuming that the optimum N rate was used, an additional 481 kha of wheat would be required to maintain UK wheat production at the current level. If the additional land area came from converting temperate grassland to arable production, the GHG emissions caused by ploughing grassland would cause emissions to rise from 503 to 713 kg CO2e per tonne of grain produced. This would result in an additional 3·15 Mt CO2e per year to produce the typical UK annual production of 15 Mt. This analysis reinforces the importance of winning the 'arms race' against pathogen evolution towards fungicide insensitivity and virulence. © 2010 The Authors. Journal compilation © 2010 BSPP.


Berry P.M.,ADAS High Mowthorpe | Spink J.,Teagasc | Foulkes M.J.,University of Nottingham | White P.J.,Scottish Crop Research Institute
Field Crops Research | Year: 2010

Four field experiments were performed in the UK in harvest seasons 2007 and 2008. Each experiment consisted of 10 winter oilseed rape varieties grown at a low level of available nitrogen (N) and at a high level of available N intended to replicate commercial practice. A combined analysis of three of the experiments with significant yield differences between the N treatments showed a significant interaction between N availability and variety for yield. Across these three experiments the proportion of yield lost when crops were grown at low N compared with high N ranged from 0.23 to 0.35 among varieties. The proportion of yield lost at low N was negatively associated with crop N uptake. There was also an interaction between N supply and variety for N use efficiency (kg of seed dry matter/kg available N) within these three experiments. Varietal differences in yield at low N correlated most closely, and positively, with crop N uptake, final crop dry matter and seeds/m2, but not N utilisation (kg seed/kg N uptake). Every additional kilogram of N taken up by the crop increased yield at low N by 0.020t/ha. The amount of N taken up after flowering was the most important phase of N uptake for determining yield differences between the varieties, with every additional kilogram of N taken up after flowering associated with a yield increase of 0.016t/ha. Each additional 1000seeds/m2 was associated with an additional 1.4kgN/ha taken up after flowering. There was no correlation between yield at low N or late N uptake and individual seed size. © 2010 Elsevier B.V.


Berry P.M.,ADAS High Mowthorpe | Spink J.,Teagasc
Field Crops Research | Year: 2012

Lodging is a major limiting factor for wheat (Triticum aestivum L.) production, yet few studies have investigated the mechanism by which it reduces yield. This paper tests the hypothesis that lodging-induced yield losses in wheat can be predicted by calculating the reduction in canopy photosynthesis that results from lodging-induced changes to the architecture of the canopy. An existing model of canopy photosynthesis has been further developed to account for the effect of lodging-induced changes to the canopy architecture on photosynthesis and grain yield. The model predicted that lodging at 90° from the vertical will reduce yield by approximately 61%. The ability of the model to predict lodging-induced yield losses was tested against observations made in three separate field experiments. The model predicted 71% of the variation in the proportion of yield lost due to lodging (Y LOSS) and the best-fit line was not significantly different from the 1:1 relationship. Sensitivity analysis showed that the proportion of yield lost was relatively insensitive to the model parameters. As a result it was shown that a simplified model could be employed without losing predictive accuracy. YLOSS=∑if(L90×0.7+L65×0.3+L25×0.1)/n In this equation i and f are the 1st and last days of grain filling, L 90 is the proportion of crop area lodged at 85-90° from the vertical, L 65 is the proportion of crop area lodged between 46° and 84°, L 25 is the proportion of crop area lodged between 5° and 45° and n is the number of days of grain filling. © 2012 Elsevier B.V.


Van den Bosch F.,Rothamsted Research | Paveley N.,ADAS High Mowthorpe | Shaw M.,University of Reading | Hobbelen P.,Rothamsted Research | Oliver R.,Curtin University Australia
Plant Pathology | Year: 2011

This paper reviews the evidence relating to the question: does the risk of fungicide resistance increase or decrease with dose? The development of fungicide resistance progresses through three key phases. During the 'emergence phase' the resistant strain has to arise through mutation and invasion. During the subsequent 'selection phase', the resistant strain is present in the pathogen population and the fraction of the pathogen population carrying the resistance increases due to the selection pressure caused by the fungicide. During the final phase of 'adjustment', the dose or choice of fungicide may need to be changed to maintain effective control over a pathogen population where resistance has developed to intermediate levels. Emergence phase: no experimental publications and only one model study report on the emergence phase, and we conclude that work in this area is needed. Selection phase: all the published experimental work, and virtually all model studies, relate to the selection phase. Seven peer reviewed and four non-peer reviewed publications report experimental evidence. All show increased selection for fungicide resistance with increased fungicide dose, except for one peer reviewed publication that does not detect any selection irrespective of dose and one conference proceedings publication which claims evidence for increased selection at a lower dose. In the mathematical models published, no evidence has been found that a lower dose could lead to a higher risk of fungicide resistance selection. We discuss areas of the dose rate debate that need further study. These include further work on pathogen-fungicide combinations where the pathogen develops partial resistance to the fungicide and work on the emergence phase. © 2011 Rothamsted Research Ltd. Plant Pathology © 2011 BSPP.


Van Den Berg F.,Rothamsted Research | Van Den Bosch F.,Rothamsted Research | Paveley N.D.,ADAS High Mowthorpe
Phytopathology | Year: 2013

Strategies to slow fungicide resistance evolution often advocate early "prophylactic" fungicide application and avoidance of "curative" treatments where possible. There is little evidence to support such guidance. Fungicide applications are usually timed to maximize the efficiency of disease control during the yield-forming period. This article reports mathematical modeling to explore whether earlier timings might be more beneficial for fungicide resistance management compared with the timings that are optimal for efficacy. There are two key timings for fungicide treatment of winter wheat in the United Kingdom: full emergence of leaf three (counting down the canopy) and full emergence of the flag leaf (leaf 1). These timings (referred to as T1 and T2, respectively) maximize disease control on the upper leaves of the crop canopy that are crucial to yield. A differential equation model was developed to track the dynamics of leaf emergence and senescence, epidemic growth, fungicide efficacy, and selection for a resistant strain. The model represented Zymoseptoria tritici on wheat treated twice at varying spray timings. At all fungicide doses tested, moving one or both of the two sprays earlier than the normal T1 and T2 timings reduced selection but also reduced efficacy. Despite these opposing effects, at a fungicide dose just sufficient to obtain effective control, the T1 and T2 timings optimized fungicide effective life (the number of years that effective control can be maintained). At a higher dose, earlier spray timings maximized effective life but caused some reduction in efficacy, whereas the T1 and T2 timings maximized efficacy but resulted in an effective life 1 year shorter than the maximum achievable. © 2013 The American Phytopathological Society.


Van Den Bosch F.,Rothamsted Research | Paveley N.,ADAS High Mowthorpe | Van Den Berg F.,Rothamsted Research | Hobbelen P.,Rothamsted Research | Oliver R.,Curtin University Australia
Phytopathology | Year: 2014

We have reviewed the experimental and modeling evidence on the use of mixtures of fungicides of differing modes of action as a resistance management tactic. The evidence supports the following conclusions. 1. Adding a mixing partner to a fungicide that is at-risk of resistance (without lowering the dose of the at-risk fungicide) reduces the rate of selection for fungicide resistance. This holds for the use of mixing partner fungicides that have either multi-site or single-site modes of action. The resulting predicted increase in the effective life of the at-risk fungicide can be large enough to be of practical relevance. The more effective the mixing partner (due to inherent activity and/or dose), the larger the reduction in selection and the larger the increase in effective life of the at-risk fungicide. 2. Adding a mixing partner while lowering the dose of the at-risk fungicide reduces the selection for fungicide resistance, without compromising effective disease control. The very few studies existing suggest that the reduction in selection is more sensitive to lowering the dose of the at-risk fungicide than to increasing the dose of the mixing partner. 3. Although there are very few studies, the existing evidence suggests that mixing two at-risk fungicides is also a useful resistance management tactic. The aspects that have received too little attention to draw generic conclusions about the effectiveness of fungicide mixtures as resistance management strategies are as follows: (i) the relative effect of the dose of the two mixing partners on selection for fungicide resistance, (ii) the effect of mixing on the effective life of a fungicide (the time from introduction of the fungicide mode of action to the time point where the fungicide can no longer maintain effective disease control), (iii) polygenically determined resistance, (iv) mixtures of two at-risk fungicides, (v) the emergence phase of resistance evolution and the effects of mixtures during this phase, and (vi) monocyclic diseases and nonfoliar diseases. The lack of studies on these aspects of mixture use of fungicides should be a warning against overinterpreting the findings in this review.


Lo Iacono G.,University of Cambridge | van den Bosch F.,Rothamsted Research | Paveley N.,ADAS High Mowthorpe
Journal of Theoretical Biology | Year: 2012

Disease resistance genes are valuable natural resources which should be deployed in a way which maximises the gain to crop productivity before they lose efficacy. Here we present a general epidemiological model for plant diseases, formulated to study the evolution of phenotypic traits of plant pathogens in response to host resistance. The model was used to analyse how the characteristics of the disease resistance, and the method of deployment, affect the size and duration of the gain. The gain obtained from growing a resistant cultivar, compared to a susceptible cultivar, was quantified as the increase in green canopy area resulting from control of foliar disease, integrated over many years-termed 'Healthy Area Duration (HAD) Gain'. Previous work has suggested that the effect of crop ratio (the proportion of land area occupied by the resistant crop) on the gain from qualitative (gene-for-gene) resistance is negligible. Increasing the crop ratio increases the area of uninfected host, but the resistance is more rapidly broken; these two effects counteract each other. We tested the hypothesis that similar counteracting effects would occur for quantitative, multi-genic resistance, but found that the HAD Gain increased at higher crop ratios. Then we tested the hypothesis that the gain from quantitative host resistance could differ depending on the life-cycle component (sporulation rate or infection efficiency) constrained by the resistance. For the patho-system considered, a quantitative resistant cultivar that reduced the infection efficiency gave a greater HAD Gain than a cultivar that reduced sporulation rate, despite having equivalent transmission rates. © 2012 Elsevier Ltd.

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