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Potato (Solanum tuberosum) stem density variation in the field can be used to inform harvest timing to improve tuber size distribution. Current methods for quantifying stem density are manual with low throughput. This study examined the use of Unmanned Aerial Vehicle imagery as a high-throughput alternative. A colour-based feature extraction technique and a deep convolutional neural network (CNN) were compared for their effectiveness in enumerating apical meristems as a proxy to subtending stems. Two novel colour indices, named the cumulative blue differences index and blue difference normalized index, showed significant differences (P

Batch adsorption experiments were performed to determine the sorption of the nematicide fluensulfone as a technical-grade and a granular formulation (as Nimitz 15G) in six UK arable soils. The Freundlich and equilibrium sorption coefficients and , respectively, were generally low. and correlated positively with soil organic matter in all instances. The sorption kinetics was similar for both forms, but the was about four times lower for Nimitz 15G than the technical-grade, suggesting concentration dependency of fluensulfone sorption. The low sorption of fluensulfone across the soils indicates that partitioning of fluensulfone to the soil liquid phase may be unlimited. Therefore, substantial availability in the soil to be effective is likely. Sorption, therefore, may not limit fluensulfone efficacy. Nonetheless, these results call for cautious use of the nematicide because leaching is possible.

Increase in drought conditions during the oilseed rape (OSR) reproductive phase is predicted to occur more often in the temperate zone, leading to significant yield losses. Crop management solutions such as film antitranspirant (AT) applied at key drought-sensitive growth stages on both wheat and oilseed rape have recently been shown to alleviate drought-induced yield losses. However, there is a lack of information regarding potential AT effectiveness to reduce drought damage on OSR plants at different soil moisture regimes. Therefore, two similar experiments were performed in a computer-controlled glasshouse/phenotyping centre to investigate the physiological responses of OSR to well-watered (WW), moderate water stress (MWS), water stress (WS) and severe water stress (SWS) conditions. Stress treatments were imposed at the initiation of flowering and treated with an AT or water onto the leaf canopy. Stress limited the gas-exchange and increased leaf temperature, leaf-to-air temperature, bud-to-air temperature and ABA concentrations which increased with stress intensity in all tissues analysed. Yield components were significantly reduced by WS and SWS treatments when compared to the WW plants. Application of AT counteracted the detrimental effect of WS and SWS by decreasing water use over the first few days of stress application thus improving relative water content and leaf water-use efficiency, decreasing ABA accumulation in leaf and all the reproductive organs analysed (buds, flowers and pods) and avoiding bud-to-air temperature increases. AT application sustained pod formation and seed production under WS but only seed production under SWS conditions. These data suggest that leaf-canopy application of AT at key phenological stages under particular magnitudes of soil moisture deficit may sustain OSR reproduction and reduce yield losses.

As part of a broader study to evaluate the efficacy of fluensulfone for control of the potato cyst nematode,Globodera pallida, two field experiments in Shropshire (at Woodcote and Howle in 2010 and 2011, respectively) England, were used to monitor the persistence of fluensulfone in potato beds treated with Nimitz 15G®(fluensulfone) at 27 kg ha−1. Fluensulfone dissipated at similar rates in the two fields, with a trend best described by a sigmoidal curve. The time to 50% dissipation (DT50) was 24.3 days at Woodcote, and 23.7 days at Howle. No differences were found between the DT50for fluensulfone and that observed for fosthiazate. The short DT50demonstrated for fluensulfone in this study is a positive attribute as this nematicide may pose a negligible hazard to the environment. However, its persistence at an effective dose may be long enough to be effective over the peak hatch period ofG. pallida.

Splitting is a problem that seriously affects appearance and marketability in a number of fruit and vegetables. In summer radish (Raphanus sativus L.), splitting can occur during growth, harvesting and postharvest. We investigated the factors affecting splitting susceptibility in summer radish cv. Celesta during postharvest handling.Splitting susceptibility was negatively related to temperature, with higher temperature reducing splitting due to dropping impact. Radish diameter was positively associated with compression failure force, suggesting that larger radishes are more resistant to compressive splitting. An increase in radish hypocotyl water content (WC) was associated with an increase in splitting susceptibility due to impact and decrease in failure force for both compression and puncture forces. Increased hypocotyl WC may increase splitting susceptibility by increasing the water potential of the radish tissue. In agreement, we found that increased hypocotyl WC was associated with higher internal water potential in radish tissue.We therefore recommend that the hypocotyl WC of summer radish crops be managed during the harvest and postharvest phases, and that crops are processed at higher, ambient, temperature in order to reduce splitting, before storing at low temperature and high humidity to maintain quality and shelf life. © 2020 The Authors. Journal of The Science of Food and Agriculture published by John WileySons Ltd on behalf of Society of Chemical Industry.

Drought stress reduces seed crop yields in part by causing reproductive sterility associated with increased endogenous ABA. Application of the film antitranspirant, di-1-p-menthene, during reproductive-stage drought has been shown to ameliorate yield loss in wheat but the physiological processes involved are not understood. Using rain shelters to simulate Mediterranean-type terminal drought, we studied the possibility that application of the antitranspirant reduces both endogenous ABA concentration and the subsequent yield loss. Di-1-p-menthene was sprayed on droughted spring wheat plants (cv, Chilham) at 1.0 L/ha in two separate field experiments, at three growth stages between stem elongation and spike emergence in 2018; and at four growth stages between stem elongation and anthesis in 2019, with droughted but unsprayed plants serving as the control. Drought stress increased endogenous ABA but decreased yield. Di-1-p-menthene application reduced endogenous ABA concentration by 33% and 40%; and improved grain yield by 16% and 15% averaged across all growth stages in 2018 and 2019, respectively. The consistent effects of di-1-p-menthene in both years suggests that the mechanism of drought stress amelioration by the film antitranspirant is related to reduced endogenous ABA concentration during key growth stages.

BACKGROUND Postharvest pinking is a serious issue affecting lettuce quality. Previous studies suggested the possibility of using deficit irrigation to control discolouration; however, this approach may also affect yield. This study investigated the effect of varying irrigation deficits on iceberg lettuce (Lactuca sativa L.) to determine the relationship between irrigation deficit, pinking and fresh weight. RESULTS The deficit imposed and head fresh weight obtained depended on both the duration and timing of withholding irrigation. Withholding irrigation for a period of 2 or 3 weeks in the middle or end of the growth period significantly reduced rib pinking compared to well-watered controls. Withholding irrigation for 2 weeks at the start of the growth period or 1 week at the end did not significantly reduce pinking. Withholding irrigation also reduced head fresh weight such that minimising pinking would be predicted to incur a loss of 40% relative to well-watered controls. However, smaller benefits to pinking reduction were achieved with less effect on head fresh weight. CONCLUSION Deficit irrigation could be used to provide smaller but higher quality heads which are less likely to be rejected. The balance of these factors will determine the degree of adoption of this approach to growers.

BACKGROUND Three field experiments evaluated the performance of the nematicide fluensulfone against the potato cyst nematode Globodera pallida in Shropshire, England. RESULTS Experiments 1 and 2 showed reduced root infection and lowered multiplication of G. pallida following fluensulfone (Nimitz 15G ®) soil treatments at five rates (1.95, 3.00, 4.05 (full rate), 5.05 and 6.00 kg AI ha−1) and Nimitz 480EC ® at the full rate. Experiment 3 demonstrated a positive interaction between the full rate of Nimitz 15G and the potato variety Santé in the reduction of G. pallida. The fluensulfone treatments at the full rate had more consistent effects than the lower rates, and there were no greater effects for the treatments higher than this full rate. Generally, fluensulfone was less efficacious than oxamyl or fosthiazate, which suggests that the treatment may not be reliably integrated within shorter potato rotations. CONCLUSION The data suggest that fluensulfone soil application could make a useful addition to the few available nematicide treatments for the control of G. pallida rather than be a substitute for these treatments.© 2016 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

About 80 % of global farmland is under rain-fed conditions and most of it is prone to drought, which limits crop productivity. Due to climate change, drought will become more frequent and severe, threatening world food security. Antitranspirants, materials that reduce transpiration, could potentially result in greater food production by realising more of a crop’s potential yield during drought. Despite antitranspirants reducing photosynthesis, research has shown that they can mitigate drought stress and increase grain yield. Although this paper is not restricted to specific years, part of it is a systematic review of 173 original research articles published between 2009 and 2018. Overall, the analysis suggests that interest in the potential of antitranspirants is growing. One major achievement in antitranspirant research during the past decade was establishing the optimal timing of application of the substances, which is linked to reproductive processes most vulnerable to drought. Despite research evidence of the efficacy of antitranspirants in ameliorating drought stress, they are not widely used for commercial arable crop production. However, in fruit horticulture, products with antitranspirant effects are already being used commercially for various non-antitranspirant purposes. More recent research shows that with knowledge of a crop's growth stage and soil moisture, antitranspirants can be a valuable option for managing drought impacts on yield in arable crops.

The crop water stress index (CWSI) has been shown to be a tool that could be used for non-contact and real-time monitoring of plant water status, which is a key requirement for the precision irrigation management of crops. However, its adoption for irrigation scheduling is limited because of the need to know the baseline temperatures which are required for its calculation. In this study, the canopy temperature of greenhouse cultivated lettuce plants which were maintained as either well-watered or non-transpiring was continuously monitored along with prevailing environmental conditions during a five week period. This data was applied in developing a dynamic model that can be used for predicting the baseline temperatures. Input variables for the dynamic model included air temperature, shortwave irradiance, and air vapour pressure deficit measured at a 10 s interval. During a follow up study, the dynamic model successfully predicted the baseline temperatures producing mean absolute errors (MAE) that varied between 0.17 °C and 0.29 °C, and root mean squared errors (RMSE) that varied between 0.21 °C and 0.35 °C when comparing model predictions with measured values. The model predicted baseline temperatures were applied in calculating an empirical CWSI for lettuce plants receiving one of two irrigation treatments. The empirical CWSI consistently differentiated between the irrigation treatments and was significantly correlated with the theoretical CWSI with correlation coefficient (r) values greater than 0.9. The dynamic model presented in this study requires easily measured input parameters for the prediction of the baseline temperatures. This eliminates the need to maintain artificial reference surfaces required in other empirical approaches for the CWSI calculation and also eliminates the need for computing the complex theoretical CWSI. ispartof: COMPUTERS AND ELECTRONICS IN AGRICULTURE vol:153 pages:102-114 status: published

Fresh produce is highly perishable and significant wastage can occur from producer to consumer. Lettuce heads and other leafy salads can often suffer non-infectious discolouration disorders, such as pinking. Pinking of lettuce butts and leaves can occur within only a few days of harvest, and this can limit product shelf life and contribute to retail consumer dissatisfaction. It has already been shown that preharvest water stress can have an impact on the yield and postharvest quality of ‘Batavia’ lettuce. Our aim was to investigate the sensitivity of ‘Iceberg’ lettuce to water stress pre- and postharvest. A lettuce crop was grown in a polytunnel at Harper Adams University; soil was amended with peat to give two defined uniform soil types; 25% (high OM soil) or 5% (low OM soil) in containers of 180 L volume. By alternating the amount of irrigation a range of different water stress treatments were imposed. Increased irrigation led to greater biomass production, with heads containing a greater proportion of water. Analysis also showed that soil type and irrigation significantly affected the total amount of N (%) in lettuce head dry matter, whilst postharvest scoring revealed that the pinking score after 20 days in cold storage was significantly greater in treatments with increased irrigation.

The number of generations completed by a UK field population of Heterodera schachtii on winter and spring oilseed rape (OSR; Brassica napus L.) during the growing season of 2010/2011 was investigated. The experiments were conducted in pots outdoor using UK OSR winter cultivars (cvs) Flash and Castille and spring cvs Belinda and Heros. The results indicated that temperature was crucial in determining the number of generations completed on OSR during the growing season. At least one generation was completed on cv. Castille, whilst two generations were completed on cvs Flash, Belinda and Heros during the growing season. Development of H. schachtii was faster on hybrid OSR cvs Flash and Belinda, suggesting that the hybrids were better hosts of H. schachtii than the conventional cvs Castille and Heros. Cultivar Flash was more susceptible to H. schachtii infection than cv. Castille, while cv. Belinda was more susceptible than cv. Heros. However, no major plant growth differences were observed between the cvs investigated. This is the first report on the number of generations of H. schachtii completed on current cultivars of OSR in the UK.

Dwindling water supplies, increasing drought frequency and uncertainties associated with a changing climate mean Europe's irrigated agriculture sector needs to improve water efficiency and produce more 'crop per drop'. This paper summarizes the drivers for change, and the constraints and opportunities for improving agricultural water management through uptake of precision irrigation technologies. A multi-disciplinary and integrated approach involving irrigation engineers, soil scientists, agronomists and plant physiologists will be needed if the potential for precision irrigation within the field crop sector is to be realized. © 2013 Society of Chemical Industry

In vitro and glasshouse studies were initiated to determine the mechanisms of action of an aqueous garlic extract, salicylaldehyde, a nonylphenol ethoxylate surfactant and a formulation (G8014S) containing these substances on the potato cyst nematode Globodera pallida. The effects of these substances on host finding and migration of second-stage juveniles (J2) were assessed by investigating their ability to migrate through a sand column and towards potato roots in Pluronic F-127 gel. The garlic extract was shown to be the least disruptive to J2 host finding, reducing attraction by between 13 and 24% at concentrations of 7840 μl l−1 and 983 μl l−1, respectively. By contrast, a reduction of approximately 38% in J2 attraction to roots was achieved by treating J2 with 344 μl l−1 of G8014S. Of all the substances tested, salicylaldehyde was the least attractive to G. pallida J2 (4.1%) while the garlic extract and oxamyl treatments attracted 43.5 and 28.9% J2, respectively. In glasshouse experiments, different rates of the test substances were compared with the nematicide oxamyl for their effects on the in-soil hatch, egg viability and multiplication of G. pallida. The effect of treatment with 220.16 l ha−1 of G8014S on G. pallida multiplication in the glasshouse was comparable to that of oxamyl causing a five-fold reduction in PCN multiplication relative to the water control. These results provide evidence to support the potential of the formulation for the control of G. pallida in potatoes.

The productivity of many important crops is significantly threatened by water shortage, and the elevated atmospheric CO

Postharvest pinking is a serious issue affecting lettuce quality. Previous studies suggested the possibility of using deficit irrigation to control discolouration; however, this approach may also affect yield. This study investigated the effect of varying irrigation deficits on iceberg lettuce (Lactuca sativa L.) to determine the relationship between irrigation deficit, pinking and fresh weight.The deficit imposed and head fresh weight obtained depended on both the duration and timing of withholding irrigation. Withholding irrigation for a period of 2 or 3 weeks in the middle or end of the growth period significantly reduced rib pinking compared to well-watered controls. Withholding irrigation for 2 weeks at the start of the growth period or 1 week at the end did not significantly reduce pinking. Withholding irrigation also reduced head fresh weight such that minimising pinking would be predicted to incur a loss of 40% relative to well-watered controls. However, smaller benefits to pinking reduction were achieved with less effect on head fresh weight.Deficit irrigation could be used to provide smaller but higher quality heads which are less likely to be rejected. The balance of these factors will determine the degree of adoption of this approach to growers. © 2016 Society of Chemical Industry.

Oilseed rape (OSR; Brassica napus L.) is a crop of increasing world importance and suffers yield loss when infected with Heterodera schachtii. The in vitro hatch, in planta root invasion and development of a field population of H. schachtii were investigated in six thermostatically-controlled water baths at temperatures of 5.0, 10.1, 20.5, 27.8, 32.2 and 37.5°C in a glasshouse. The UK winter OSR cvs Flash and Castille were used. Temperature was shown to have a major influence on the development of H. schachtii in OSR. The highest cumulative percentage hatch of second-stage juveniles (J2) observed over an 8-week incubation period occurred between 20.5 and 27.8°C in leachates of both OSR cultivars, indicating that this is the optimum temperature range for hatching of this population. Cumulative hatch was lowest at 37.5 and 5.0°C. Root invasion was inhibited at 5.0 and 37.5°C, whilst the highest number of J2 invaded the roots between 20.5 and 32.2°C, indicating that this is the optimum temperature range for root invasion. The life cycle took between 21 days at 20.5°C and 42 days at 5.0°C from the inoculated J2 to the J2 of the second generation, with the associated accumulated heat units (AHU) of 424 and 203 degree-days with a base temperature (Tb) of 5.0°C. The optimum temperature range (To) for development was between 20.5 and 27.8°C and the maximum (Tm) was 37.5°C. As temperature increased, the AHU required to complete the life cycle increased from 203 degree-days at 5.0°C to 1406 at 37.5°C. Leachates from both OSR cultivars stimulated more J2 to hatch than the distilled water controls. No significant cultivar differences were observed for J2 hatching, root invasion and duration of the life cycle at the different temperatures but significantly more cysts of the second generation (g root)−1 were observed in cv. Flash than cv. Castille at 27.8 and 32.2°C, suggesting that the latter cultivar is a poorer host of H. schachtii than cv. Flash. This is the first report of the effect of temperature on H. schachtii development on current winter OSR cultivars in the UK and provides insight into the potential effects of climate change on the nematode-host interaction.

The in vitro nematicidal effects of an aqueous garlic extract, salicylaldehyde, a nonylphenol ethoxylate surfactant and a formulation containing these constituents were evaluated against the potato cyst nematode, Globodera pallida. Newly hatched, infective second-stage juveniles (J2) were placed for 24, 48 and 72 h in solutions containing concentrations of the formulation from 30.080.0 μl l–1 with 20% (v/v) potato root leachate and sterile distilled water controls. The garlic extract, salicylaldehyde and surfactant treatments were assessed at concentrations proportional to their occurrence in the formulation. Hatching assays involved a series of experiments in which G. pallida cysts were incubated for 8 weeks in potato root leachate solution containing different concentrations of the test substances. A second set of experiments involved incubating cysts in different concentrations of the test substances for 2, 4 and 8 weeks prior to hatching in potato root leachate solution to determine how prior exposure to these substances influences hatching and in-egg viability. The formulation caused 100% mortality at 75.0 μl l–1 with an LC50 of 43.6 μl l–1 after 24 h exposure. Salicylaldehyde was the most toxic constituent of the formulation with an LC50 of 6.5 μl l–1 after 24 h, while the garlic extract achieved 50% J2 mortality at 983.0 μl l–1, demonstrating that the formulation and salicylaldehyde are more toxic to G. pallida in vitro than oxamyl but less toxic when compared with aldicarb. The surfactant showed no dose-dependent toxic effects on J2 when compared with the controls. Emergence of J2 from the cysts was significantly reduced by concentrations of the formulation above 688.0 μl l–1 and its equivalent concentration of salicylaldehyde, while concentrations of the formulation above 2752.0 μl l–1 and the corresponding salicylaldehyde concentrations resulted in complete irreversible hatch inhibition. Concentrations of the garlic extract below 137.6 μl l–1 caused 26% more J2 hatch in comparison to the potato root leachate solution. This study has shown that salicylaldehyde is more toxic to nematodes than the garlic extract, and is the first report of a hatch stimulatory effect of a garlic extract on G. pallida under in vitro conditions.

The increasing demands on limited water supplies worldwide require the adoption of more efficient irrigation techniques for sustainable production in agriculture. Partial rootzone drying (PRD) is one of the techniques that offer potential saving of irrigation water. This technique involves alternate irrigation to two sides of a plant root system. The studies reported here investigated PRD irrigation regimes and the optimum time of starting PRD in potatoes grown in a protected environment. In the first experiment, plants of the potato cv. Estima were exposed to five different irrigation treatments and a fully watered control at tuber initiation. The treatment that performed most similar to the control was alternate PRD to field capacity (APRD100). This treatment produced similar total leaf area, haulm fresh and dry weights, plant water status and no significant yield reduction compared with the control plants. The APRD100 treatment utilised 29% less water and increased water use efficiency (WUE) by 19%. In the second experiment, the APRD100 irrigation was started at 2, 4, 6, 8 and 10 weeks after plant emergence. Vegetative growth and yield increased with the delay of the APRD100. APRD100 started at 6 weeks after emergence did not significantly reduce fresh tuber yield but received 21% less total water with a 19% increase in WUE. The results indicate that PRD may have potential use in the potato crop for conserving irrigation water with minimal loss of yield.

Crop-management solutions that simulate plant water-saving strategies might help to mitigate drought damage in crops. Winter canola (Brassica napus L.) is significantly drought-sensitive from flowering to mid-pod development, and drought periods lead to significant yield losses. In this study, the drought-protection efficacy of different chemicals with antitranspirant activity applied just before key drought-sensitive phenological stages was tested on field-grown canola in two years. Drought was artificially imposed with rain shelters. The results suggest that in-field application of 1 L ha–1 of antitranspirant (Vapor Gard (VG), a.i. di-1-p-menthene) at GS6.0 (BBCH growth scale, initiation of flowering) mitigated drought-induced yield loss leading to a 22% seed-yield benefit on average over 2 years of experiments compared with the unsprayed unirrigated plots. No significant yield responses were found from application at GS7.0, with increasing VG concentrations (i.e. 2 and 4 L ha–1), or with an antitranspirant with short-lasting effectiveness. The data suggest that in field conditions where drought occurs during the flowering stage, application of 1 L ha–1 of VG just before the drought event can reduce yield loss. This result should encourage further work on water-saving management strategies during key drought-sensitive phenological stages as drought mitigation tools in canola and under different environments.

Hydraulic redistribution, redistribution of water upward or downward within a soil profile through roots as a consequence of root-soil water potential gradients, can be an important mechanism in transporting chemical signals (i.e. abscisic acid) to the shoot for stomatal closure or in maintaining the root system during dry periods of partial rootzone drying (PRD). PRD involves alternate irrigation to two sides of a plant root system. The study reported here investigated the occurrence and magnitude of hydraulic redistribution in glasshouse-grown potatoes (Solanum tuberosum L.) under PRD. Deuterium labelled water was applied to only one half of the root system to field capacity at tuber initiation. The roots from the drying side of the dual pot were extracted at 3, 6, 12, 18 and 24 h following watering by the dry sieving method. Water from the roots was extracted by azeotropic distillation and analysed for hydrogen isotope ratios. Hydraulic redistribution occurred the most at night when stomatal conductance was considerably lower and leaf water potential was higher (less negative). The magnitude of the redistributed water, however, did not exceed 3.5%, indicating limited water redistribution under PRD. The observed water redistribution would probably be of little significance for the survival of roots present in the upper drier portion of the soil under higher water demanding conditions but its role in sending the chemical signals to the shoot to conserve water by reducing transpiration would be of particular significance during drying periods of partial rootzone drying.

Effective management of potato cyst nematodes (PCNs) requires simple, rapid and accurate identification and quantification of field populations. Soil samples from a survey of 484 fields in potato rotations in England and Wales were used to compare the identification and quantification of PCNs using IEF, PCR, ELISA and bait plant tests. The cyst counts and bait plant test revealed that 64.3% of field samples contained PCNs. Bait plant tests increased the detection rate of PCNs in field samples by 4-6.4%. This means that some infestations are cryptic and would not normally be detected by standard counts. IEF, PCR and ELISA methods distinguished between Globodera rostochiensis and G pallida and were able to register mixed populations; however they were not in full agreement. All methods suggested that G pallida is the dominant species in the field samples tested. The PCR results indicated that 66% of field samples contained pure G pallida, 8% contained pure G rostochiensis and 26% contained mixtures of the two species. Estimates of the relative process times taken per sample in the PCR, IEF and ELISA techniques are given.

Summary Wireworms (Agriotes spp.) are sporadic but increasingly important pests of potatoes, sugar beet and cereals. Whilst effective chemical control is possible, the granular organophosphates normally require high rates of application and the seed dressings containing lindane (gamma-HCH) have been withdrawn from use. The soil fumigant 1,3-dichloropropene (1,3-D as Telone II) and the granular nematicide fosthiazate (Nemathorin 10G) are currently used for the control of potato cyst nematodes. We investigated the effects of both of these chemicals on wireworms. Air-vapour phase toxicities for 1,3-D against wireworm were LD50 2.74 mg.litre.day and LD99 5.05 mg.litre.day. The in vitro soil phase toxicity was LD99 8.15 mg.litre.day. 1,3-D soil phase activity against wireworm may be associated more with air-vapour phase than a soil-water phase activity. In glasshouse experiments 16.0 mg.litre.day of 1,3-D gave 75% control. Fosthiazate, which is applied at approximately 2 μg g−1 of soil for potato cyst nematode control, achieved an LC50 at 3.20 μg g−1. In both in vitro and glasshouse studies 1,3-dichloropropene showed high toxicity to wireworm at dosages below the current commercial application rate for potato cyst nematode control and fosthiazate also showed useful efficacy. These chemicals may therefore prove to be valuable additional tools for limiting initial wireworm plant damage or reducing wireworm populations.

Summary The use of supplementary foliar N, P and K to ameliorate the reduced nutrient uptake of potato plants infected by potato cyst nematode (PCN) were investigated. The potato cv. Pentland Dell achieved yields in plots not treated with oxamyl similar to those found in plots treated with oxamyl when supplementary foliar N or N plus K was applied to plots infested with 13 eggs g-1 soil of Globodera pallida. Yield improvements from foliar N applications were attributed to increased leaf area index but the reason for yield increases from foliar N plus K applications could not be clarified. In a second experiment, where PCN infestation was 76 eggs g-l soil, the potato cv. Sante gave yields up to 19% higher than a standard fertiliser practice when supplementary foliar N was applied to plots not treated with oxamyl. Nutrient analysis showed that without oxamyl there were significantly lower concentrations of N, P and K in whole plant dry matter at 58 days after planting (DAP) but higher levels of N in the fourth leaf dry matter at 98 DAP. Emergence was significantly advanced by the use of oxamyl in both experiments. Sante dramatically reduced populations of Globodera rostochiensis from an average of 76 eggs g-1 soil to 7 eggs g-1 soil. Foliar application of nutrients is a promising method of ameliorating the effects on potatoes of PCN invasion but the nutrient concentrations and timing of individual sprays need to be more closely matched to crop requirement than was possible in our experiments

Oilseed rape (Brassica napus L.) yield is strongly decreased by water deficit, and crop-management solutions are urgently required considering the emerging difficulties in breeding for drought-tolerant varieties. Film-forming antitranspirants (polymers) are agrochemicals that, applied to the crop canopy, mechanically block the stomata and decrease canopy transpiration. In this study, the drought-protection efficacy of an adaxial-surface application at the flowering stage of two film-forming treatments (poly-1-p-menthene and di-1-p-menthene) was investigated in pot-grown, droughted oilseed rape over two glasshouse experiments. Over the drought period, the two compounds reduced leaf stomatal conductance (P

Dwindling water supplies, increasing drought frequency and uncertainties associated with a changing climate mean Europe's irrigated agriculture sector needs to improve water efficiency and produce more 'crop per drop'. This paper summarizes the drivers for change, and the constraints and opportunities for improving agricultural water management through uptake of precision irrigation technologies. A multi-disciplinary and integrated approach involving irrigation engineers, soil scientists, agronomists and plant physiologists will be needed if the potential for precision irrigation within the field crop sector is to be realized.

Summary Potato cyst nematodes (PCN) have been known to occur in the UK for nearly a hundred years. They are the most problematic pests of potatoes and can cause severe yield losses. Previous work has shown the two species, Globodera rostochiensis and G pallida, to be distributed throughout the UK. This paper reports the results of the first structured and statistically unbiased survey undertaken to assess their occurrence and distribution in the potato growing land of England and Wales. The survey showed that PCN were present in 64% of sites sampled. Of the populations found, 67% were G pallida, 8% were G rostochiensis and 25% contained both species. The results show an increase in the incidence of PCN since previous studies were completed and confirm the perceived shift towards G pallida as the predominant species. Of the infestations found, 62% had a population density of less than 10 eggs g−1 soil.

Summary The effects of broadcast granular, placed liquid and foliar fertilisers on the tolerance of potatoes to infection by potato cyst nematodes were investigated. The tolerance of the potato cv. Pentland Dell was not significantly improved by fertiliser application type but placed liquid fertiliser, with or without foliar applications, increased the concentrations of N, P and K measured in whole plant dry matter of PCN infected plants. The tolerance of the potato cv. Sante was not statistically improved by altering the balance of fertiliser nitrogen applications between planting and tuber initiation or by applying foliar nitrogen. Nitrogen applications of 120 kg N ha-1 at planting and a further 120 kg N ha-1 at tuber initiation supplemented with foliar N, however, achieved a larger tuber yield than the same nitrogen programme without foliar N and gave a significantly greater yield than the application of 240 kg N ha-1 at planting plus foliar N. The emergence of both cultivars was delayed in the absence of oxamyl. N, P and K concentrations within whole plant dry matter were significantly higher in plants from oxamyl treated plots and both N and K concentrations were significantly increased by increasing the quantity of N at planting, at 56 DAP. Splitting the fertiliser N between planting and tuber initiation appears to be important in maintaining the availability of this nutrient to PCN infected plants throughout the season.