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1.
A method is presented to quantify the net effect of disease management on greenhouse gas (GHG) emissions per hectare of crop and per tonne of crop produce (grain, animal feed, flour or bioethanol). Calculations were based on experimental and survey data representative of UK wheat production during the period 2004–06. Elite wheat cultivars, with contrasting yields and levels of disease resistance, were compared. Across cultivars, fungicides increased yields by an average of 1·78 t ha?1 and GHG emissions were reduced from 386 to 327 kg CO2 eq. t?1 grain. The amount by which fungicides increased yield – and hence reduced emissions per tonne – was negatively correlated with cultivar resistance to septoria leaf blotch (Mycosphaerella graminicola, anamorph Septoria tritici). GHG emissions of treated cultivars were always less than those of untreated cultivars. Without fungicide use, an additional 0·93 Mt CO2 eq. would be emitted to maintain annual UK grain production at 15 Mt, if the additional land required for wheat production displaced other UK arable crops/set aside. The GHG cost would be much greater if grassland or natural vegetation were displaced. These additional emissions would be reduced substantially if cultivars had more effective septoria leaf blotch resistance. The GHGs associated with UK fungicide use were calculated to be 0·06 Mt CO2 eq. per annum. It was estimated that if it were possible to eliminate diseases completely by increasing disease resistance without any yield penalty and/or developing better fungicides, emissions could theoretically be reduced further to 313 kg CO2 eq. t?1 grain.  相似文献   

2.
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.  相似文献   

3.
Crop disease not only threatens global food security by reducing crop production at a time of growing demand, but also contributes to greenhouse gas (GHG) emissions by reducing efficiency of N fertiliser use and farm operations and by driving land use change. GHG emissions associated with adoption of reduced tillage, organic and integrated systems of field crop production across the UK and selected regions are compared with emissions from conventional arable farming to assess their potential for climate change mitigation. The reduced tillage system demonstrated a modest (<20%) reduction in emissions in all cases, although in practice it may not be suitable for all soils and it is likely to cause problems with control of diseases spread on crop debris. There were substantial increases in GHG emissions associated with the organic and integrated systems at national level, principally due to soil organic carbon losses from land use change. At a regional level the integrated system shows the potential to deliver significant emission reductions. These results indicate that the conventional crop production system, coupled to reduced tillage cultivation where appropriate, is generally the best for producing high yields to minimise greenhouse gas emissions and contribute to global food security, although there may be scope for use of the integrated system on a regional basis. The control of crop disease will continue to have an essential role in both maintaining productivity and decreasing GHG emissions.  相似文献   

4.
Climate change will affect both growth of agricultural crops and diseases that attack them but there has been little work to study how its impacts on crop growth influence impacts on disease epidemics. This paper investigates how impacts of climate change on wheat anthesis date will influence impacts on fusarium ear blight in UK mainland arable areas. A wheat growth model was used for projections of anthesis dates, and a weather-based model was developed for use in projections of incidence of fusarium ear blight in the UK. Daily weather data, generated for 14 sites in arable areas of the UK for a baseline (1960–1990) scenario and for high and low CO2 emissions in the 2020s and 2050s, were used to project wheat anthesis dates and fusarium ear blight incidence for each site for each climate change scenario. Incidence of fusarium ear blight was related to rainfall during anthesis and temperature during the preceding 6 weeks. It was projected that, with climate change, wheat anthesis dates will be earlier and fusarium ear blight epidemics will be more severe, especially in southern England, by the 2050s. These projections, made by combining crop and disease models for different climate change scenarios, suggest that improved control of fusarium ear blight should be a high priority in industry and government strategies for adaptation to climate change to ensure food security.  相似文献   

5.
In 1980, field inoculations withSeptoria tritici were performed on winter wheat cv. Okapi. Leaf necrosis progress curves were established; they were sigmoid and could be transformed into logit lines. There was a great difference in the slope of the logit lines between inoculated plots and non-inoculated controls. The mid-time values varied according to inoculum dosage and post-inoculation humidity treatment. Yields (kg ha?1) and average grain weights (mg grain?1) differed significantly between inoculated and non-inoculated plots, but seldom among inoculation treatments. Decrease of average grain weight completely explained yield loss, which was 878 kg ha?1 or 12% of control (7045 kg ha?1). This crop loss is considerable for a cultivar which is not particularly susceptible. A good correlation was found between the amount of necrosis at development stages DC=75 and 77 and yield depression. The integral of necrosis over time gave a high correlation with loss of kernel weight.  相似文献   

6.
BACKGROUND: A major global challenge is to provide agricultural production systems that are able to sustain growing demands for food, feed, fibre and renewable raw materials without exacerbating climate change. Detailed and reliable data on the CO2 balance of different agricultural management activities and inputs as a basis to quantify carbon footprints of agriculture are still lacking. This study aims to fill this gap further by quantifying the net balance of emitted and assimilated CO2 due to the application of crop protection treatments on the farm, and by assessing their partial contribution to GHG emissions and mitigation in agriculture. The study focuses on key agricultural crops including wheat, corn, oilseeds and sugar crops. RESULTS: The final CO2 balance, considering GHG emissions due to on‐farm CPP treatment in comparison with CO2 storage in additional biomass, CO2 protected with respect to agrotechnical inputs and land inputs and CO2 saved with respect to associated global land use changes, is positive and may reach multiples of up to nearly 2000. CONCLUSION: The results highlight the importance of the positive yield effects of the CPP programme applications on the farm, resulting in additional assimilated biomass at the farm level and less land use changes at the global level, and thus lower pressure on environmentally important indicators of overall agricultural sustainability. Copyright © 2012 Society of Chemical Industry  相似文献   

7.
Various control strategies for Achillea millefolium L. (yarrow) were investigated in a dense stand of the weed at Lincoln College in 1977–1978. In early spring plots were either rotary cultivated or left undisturbed. In late spring, plots of both previous treatments were either left undisturbed, rotary cultivated or sprayed with glyphosate at 1·5 kg ha?1. The whole experiment was rotary cultivated twice 1 week later and sown with Hordeum vulgure L. cv. Zephyr (barley) at 144 kg seed ha?1. MCPA + dicamba at 0·9+0·15 kg ha?1 was applied to half of each plot when the second node was detectable (Zadok 32). Rotary cultivation and glyphosate both substantially reduced the regrowth of A. millefolium but glyphosate reduced regrowth by a greater proportion when applied to undisturbed plants than when applied to plants regenerating after cultivation. Both gave a more than 95% reduction compared to the control (rotary cultivation only at sowing time) in the amount of A. millefolium present in the barley stubble in the autumn. MCPA + dicamba caused seedling mortality but did not affect the numbers of primary shoots from rhizome fragments. The grain yield of the barley increased from 2·91 t ha?1 when A. millefolium was not controlled to 4·23 t ha?1 with good control. The barley yield appeared to be restricted by competition from regenerating A. millefolium and by a nitrogen deficiency induced in some regimes by nitrogen immobilization in decaying rhizomes.  相似文献   

8.
The effect of Agrostemma githago L. and other naturally occurring weeds on biomass production and grain yield was studied in winter wheat and winter barley. Naturally occurring weeds had only a negligible effect on barley, but reduced wheat grain yield by 10% at a quarter of normal crop density. The interaction between the cereals and A. githago was studied in additive series employing different crop densities. Growth of this weed species was strongly dependent on crop density, which was more important for controlling weed growth than it was for obtaining a normal grain yield. Wheat and especially barley had a better competitive ability than A. githago. Wheat and A. githago utilized resources for growth better when grown in mixture than when grown in pure stands as the relative yield totals were significantly larger than unity.  相似文献   

9.
Weed seeds present an agronomic threat, but are also an important food resource for wildlife in winter. Weed seed densities on the soil surface in winter were examined from 1999 to 2002 in 105 fields on three different farms in UK. The effect of the preceding crop, cultivation, position within the field and the application of seed for birds (bird seed) on surface seed abundance and species composition was tested. Six or fewer species comprised c. 80% of the weed seeds. By January of each study year, the densities of seeds important for farmland birds (key seeds) were 73% or 87% lower compared with early winter on two of the farms, but were stable on the third where seeds were incorporated through cultivation. At the edge and mid‐field, seed densities only exceeded 400 m?2 in 17%, 10% and 12% of fields for total, key and dicotyledonous seeds respectively. The preceding crop only affected seed densities at one site; stubbles of winter barley had fewer seeds compared with winter wheat or spring barley. Seed densities varied between the edge and mid‐field, but trends were inconsistent between sites. The density of the larger seeds (Atriplex patula, Viola arvensis, Polygonum aviculare and Chenopodium album) were reduced in fields receiving bird seed. The objectives of weed control and conservation may not be mutually exclusive because seed return was most reduced where the ground remained uncultivated through the winter, yet this also provided the best foraging opportunities for surface feeding seed predators.  相似文献   

10.
In crops of winter barley, cvs Igri and Halcyon, crop structure and intensity of foliar diseases were altered by delaying the main top dressing of nitrogen until mid-April. A single application of fungicide then was sufficient to decrease substantially the severity of fungal disease and improve grain yield at harvest.
Disease control and yield responses were greatest when fungicides were applied during a 3-week period after the main nitrogen application in April. No additional yield benefits were obtained by making two fungicide applications at growth stage (GS) 31 and GS 39.  相似文献   

11.
The effects of different populations of volunteer winter wheal and their control with ethofumesate and TCA on growth, seed yield and yield components of S.24 perennial ryegrass were investigated in lield experiments in 1978 and 1979. Reductions in ryegrass seed yield due to the presence of wheat depended on the density of wheat and the number and dry weight of ryegrass tillers. The greatest percentage reduction in ryegrass seed yield occurred at high densities of wheat (300 plants m?2) when the number of ear-bearing tillers and 1000 seed weight of ryegrass were reduced. When Ihe density of wheat was low (80 plants m?2) a smaller reduction in ryegrass seed yield occurred and the number of live wheat plants remaining gradually decreased. Within the range of wheat densities in these experiments (0–300 plants m ?2) a 1% loss in ryegrass seed yield occurred for every 10 wheal plants m?2 present in the crop post winter. Both herbicides caused a reduction in number of ryegrass tillers during growth but, except where TCA was applied at 12 kg ha?1 in November, ryegrass seed yields were not significantly reduced (in comparison with a wheat-free control) and were always greater than those obtained in the presence of wheat where no herbicides had been applied. Levels of volunteer infestation of 300 wheat plants m?2 were controlled with minimum risk of crop damage by applications of 6 kg ha?1 TCA in either October or November, or by application of 1–9 kg ha?1 ethofumesate in November.  相似文献   

12.
The feasibility of achieving selective wild oat (Avena fatua L.) control in a stand of the Australian oat (Avena sativa L.) cv. Savena I was examined. Diclofop-methyl was applied at rates of 0·4–0·7 kg a.i. ha?1 at the three- and five-leaf stages of A. fatua (84–132 culms m2). Although all rates of diclofop-methyl caused initial chlorosis and necrosis to the crop, the subsequent control of A. fatua permitted increased crop tillering. Avena fatua control and crop yield response were maximized when diclofop-methyl was applied at the three-leaf stage. Crop grain yield was increased by as much as 32% and 22% during 1984 and 1985, respectively. In the absence of A. fatua competition, crop shoot dry weight at ear emergence was reduced only where diclofop-methyl was applied at 0·6 or 0·7 kg ha?1. However, final grain yield was not reduced by any treatment. Only 11 of 240 cultivars or lines tolerated diclofop-methyl, and none reached the level attained by Savena I and a closely related Australian line [(Irwin × (West × New Zealand Cape/42)) × West]/24. The nature of the inheritance of diclofop-methyl tolerance was examined (1983–1985) by crossing and backcrossing (BC) Savena I with four diclofop-methyl susceptible, but agronomically superior, lines. Inheritance of diclofop-methyl tolerance appeared to be controlled by two genes, with susceptibility being dominant to tolerance in F3, BCIF2 and BCIF3 lines.  相似文献   

13.

Current control of scab and mildew of apple in the UK requires the routine application of fungicides at 7 - 14-day intervals to achieve the blemish-free fruit required by the market. Such practices are generally effective, but with increased public concern about pesticides and rising costs to the grower, they are now less acceptable. The use of disease-warning systems offers scope for optimizing fungicide use by better timing of sprays. Adem? is a PC-based system that warns of the risk of scab, mildew, Nectria fruit rot and canker and fireblight. In a 'key stage' strategy, warnings by Adem? for scab and mildew integrated with practical pest and disease control resulted in similar or better control than a routine programme, with the additional benefit of reduced fungicide inputs and costs even in seasons exceptionally favourable for these diseases. Maximum savings in fungicide use were made by applying sprays curatively in response to scab warnings. However, this approach resulted in increased disease incidence to the crop and scab infection of fruit even in seasons unfavourable for scab attack.  相似文献   

14.
Studies on competition between Ridolfia segetum Maris, and sunflower (Helianthemum annuus L.) were conducted at eight locations in southern Spain in 1990 and 1991. in order to define competition models and to estimate from these economic thresholds as affected by crop inputs and potential yields. Competition losses in sunflower crops ranged from 19% to 56% of weed–free yields. There were slightly better correlations between percentage sunflower reduction and weed density than with weed dry weight, (?0.66 and ?0.59, respectively). The weed competitive index, or sunflower crop dry weight reduction per unit dry weight of R. segetum, was 1.09. The percentage yield losses due to weed density (NPRt) were fitted to multiple linear, quadratic, exponential and hyperbolic models. The hyperbolic equation, %RSY=100 (1+1/b*NPRt)?1, where b=0.14 and is the R. segetum competitive ability index, had the lowest error sum of squares (SSE), and gave the best biological explanation for the competition response. Early emergence (before mid–March) made weeds about 1.5 times more competitive than late emergence. The economic threshold to offset the cost of a shallow post–emergence tillage, assuming 70% control efficiency, ranged from about 2.5 plants m ?2 for low–yielding crops(1200kgha?1) to less than one plant m?2 for higher–yielding crops (2800 kg ha?1).  相似文献   

15.
In this study, we used Parthenium hysterophorus and one of its biological control agents, the winter rust (Puccinia abrupta var. partheniicola) as a model system to investigate how the weed may respond to infection under a climate change scenario involving an elevated atmospheric CO2 (550 μmol mol?1) concentration. Under such a scenario, P. hysterophorus plants grew significantly taller (52%) and produced more biomass (55%) than under the ambient atmospheric CO2 concentration (380 μmol mol?1). Following winter rust infection, biomass production was reduced by 17% under the ambient and by 30% under the elevated atmospheric CO2 concentration. The production of branches and leaf area was significantly increased by 62% and 120%, under the elevated as compared with ambient CO2 concentration, but unaffected by rust infection under either condition. The photosynthesis and water use efficiency (WUE) of P. hysterophorus plants were increased by 94% and 400%, under the elevated as compared with the ambient atmospheric CO2 concentration. However, in the rust‐infected plants, the photosynthesis and WUE decreased by 18% and 28%, respectively, under the elevated CO2 and were unaffected by the ambient atmospheric CO2 concentration. The results suggest that although P. hysterophorus will benefit from a future climate involving an elevation of the atmospheric CO2 concentration, it is also likely that the winter rust will perform more effectively as a biological control agent under these same conditions.  相似文献   

16.
The effects of sub‐lethal dose of herbicide and nitrogen fertilizer on crop–weed competition were investigated. Biomass increases of winter wheat and a model weed, Brassica napus, at no‐herbicide treatment with increasing nitrogen were successfully described by the inverse quadratic model and the linear model respectively. Increases in weed competitivity (β0) of the rectangular hyperbola and parameter B in the dose–response curve for weed biomass, with increasing nitrogen were also successfully described by the exponential model. New models were developed by incorporating inverse quadratic and exponential models into the combined rectangular hyperbola with the standard dose–response curve for winter wheat biomass yield and the combined standard dose—response model with the rectangular hyperbola for weed biomass, to describe the complex effects of herbicide and nitrogen on crop–weed competition. The models developed were used to predict crop yield and weed biomass and to estimate the herbicide doses required to restrict crop yield loss caused by weeds and weed biomass production to an acceptable level at a range of nitrogen levels. The model for crop yield was further modified to estimate the herbicide dose and nitrogen level to achieve a target crop biomass yield. For the target crop biomass yield of 1200 g m?2 with an infestation of 100 B. napus plants m?2, the model recommended various options for nitrogen and herbicide combinations: 140 and 2.9, 180 and 0.9 and 360 kg ha?1 and 1.7 g a.i. ha?1 of nitrogen and metsulfuron‐methyl respectively.  相似文献   

17.
False smut, caused by Ustilaginoidea virens, is an important emerging disease of rice (Oryza sativa L.) in China. Up to now, as most varieties with high yielding and good quality are susceptible or even highly susceptible to false smut in most rice-growing ecological regions, especially in Anhui Province, chemical control with fungicides would be an important measure for the control of this disease. The ergosterol biosynthesis inhibitor (EBI) fungicides, such as prochloraz, difenoconazole, propiconazole and tebuconazole, are extensively used in China for the control of rice diseases, such as rice sheath blight and rice blast. In this study, a total of 102 U. virens isolates (from Anhui Province of China) were tested for their sensitivity to these four EBI fungicides during the stage of mycelial growth. The EC50 ranges of values for prochloraz, difenoconazole, propiconazole and tebuconazole inhibiting mycelial growth of the 102 U. virens isolates were 0.04–0.75, 0.04–1.08, 0.04–0.38 and 0.03–0.57 μg?ml?1, with the average EC50 values of 0.32?±?0.08, 0.45?±?0.08, 0.19?±?0.03 and 0.21?±?0.06 μg?ml?1, respectively. These values suggested that the tested U. virens isolates were very sensitive to these four EBI fungicides. Results of field trials showed that two sprays of three of the fungicides exhibited greater control efficacy than a single spray for the control of rice false smut. Two sprays of each was better than a single spray for the control of rice sheath blight. Two sprays of 50% propiconazole EC at 300 g a.i. ha?1 gave the best control of rice false smut at both two sites during the two consecutive years, 2010 and 2011, with the control efficacy ranging from 71.5 to 74.3%. Sensitivity of the field U. virens isolates to EBI fungicides should be monitored. Mixtures, as well as alternation with other fungicides with different modes of action, should be tested.  相似文献   

18.
A field trials programme was conducted in which the performance of a new emulsifiable concentrate formulation (ECI) of flamprop-M-isopropyl containing the adjuvant, ‘Dobanol’ 25-7, in a ratio of 2:1 (by weight) with the AI, was compared with the current commercial formulation of ‘Commando’, in combination with its recommended adjuvant, ‘Swirl’, for the control of wild oat (Avena fatua L.) in wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.). A further treatment, in which the ‘Dobanol’ 25-7: AI ratio was increased to 4:1 by the spray tank addition of the former, was also included. The mean results from six trials (five wheat, one barley) showed that the addition of ‘Swirl’ to ‘Commando’ was beneficial, increasing wild oat floret control from a mean value of 80% to 92% at current recommended rates (flamprop-M-isopropyl, 600 g ha?1; ‘Swirl’, 2.5 litre ha?1). However, combinations of flamprop-M-isopropyl and ‘Dobanol’ 25-7 gave superior levels of control even at lower AI application rates. For example, a mean level of 96% control of Avena spp. was obtained at 300 g AI ha?1 with 1200 g ha?1 ‘Dobanol’ 25–7; with even better control at higher rates of application of both components. This improvement in performance was accompanied by a higher risk of crop phytotoxicity than observed with the ‘Commando’/‘Swirl’ mixtures. Symptoms initially were scorch and subsequently growth depression, particularly of tillers. None of the mean values in the six ‘efficacy’ trials reached commercially unacceptable levels, but in a further six ‘crop effects’ trials (three wheat, three barley), in which double rates were applied, the levels of phytotoxicity did become unacceptable and subsequently reduced grain yields. In contrast, two barley ‘crop effects’ trials gave yields higher than the control plots, possibly through the effects of reducing stem length and lodging thereby enabling more efficient harvesting. Nevertheless, there were rates of application of flamprop-M-isopropyl in the range 300–400 g ha?1 with ratios of ‘Dobanol’ 25-7 in the range 2:1 to 4:1 that would achieve high levels of control of Avena spp. without undue risk of crop phytotoxicity and further trials are planned to support this new adjuvant system.  相似文献   

19.
Pre-harvest application of glyphosate in barley at 1·44 and 0·72 kg ha?1 was compared with post-harvest application at 1·44 kg ha?1 at six sites in south-east Scotland, three sprayed in 1980 and three in 1981. Both levels of pre-harvest application gave consistent 95–99% control of A. repens compared with 0–76% control from post-harvest application. Yields of crops grown in 1981 were significantly increased after all the 1980 pre-harvest treatments and after one post-harvest treatment. No significant depressions in grain germination were recorded from the lower rate of pre-harvest application but one significant depression was recorded from the higher rate. Combine harvesting throughput at a given grain loss level was significantly improved by pre-harvest application and moisture content of grain at harvest was significantly reduced by up to 2·5%. Wheeling losses from pre-harvest spraying ranged from 1 to 5%. Crop yield increases in the year after spraying compensated for herbicide and application costs plus any yield losses through tractor wheelings.  相似文献   

20.
This review describes environmental factors that influence severity of crop disease epidemics, especially in the UK and north-west Europe, in order to assess the effects of climate change on crop growth and yield and severity of disease epidemics. While work on some diseases, such as phoma stem canker of oilseed rape and fusarium ear blight of wheat, that combine crop growth, disease development and climate change models is described in detail, climate-change projections and predictions of the resulting biotic responses to them are complex to predict and detailed models linking climate, crop growth and disease development are not available for many crop-pathogen systems. This review uses a novel approach of comparing pathogen biology according to ‘ecotype’ (a categorization based on aspects such as epidemic type, dissemination method and infection biology), guided by detailed disease progress models where available to identify potential future research priorities for disease control. Consequences of projected climate change are assessed for factors driving elements of disease cycles of fungal pathogens (nine important pathogens are assessed in detail), viruses, bacteria and phytoplasmas. Other diseases classified according to ‘ecotypes’ were reviewed and likely changes in their severity used to guide comparable diseases about which less information is available. Both direct and indirect effects of climate change are discussed, with an emphasis on examples from the UK, and considered in the context of other factors that influence diseases and particularly emergence of new diseases, such as changes to farm practices and introductions of exotic material and effects of other environment changes such as elevated CO2. Good crop disease control will contribute to climate change mitigation by decreasing greenhouse gas emissions from agriculture while sustaining production. Strategies for adaptation to climate change are needed to maintain disease control and crop yields in north-west Europe.  相似文献   

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