Determinants of Fungicide Spray Decisions for Wheat

Paveley, N. D.; Lockley, K. D.; Sylvester‐Bradley, R.; Thomas, J. M.

doi:10.1002/(sici)1096-9063(199704)49:4<379::aid-ps513>3.0.co;2-g

Cited by 31 publications

(17 citation statements)

References 13 publications

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“…Fungicides serve to delay the loss of green leaf area to disease, and so to increase yield as leaves can photosynthesize for longer (Paveley et al ., 1997) Therefore the decrease in leaf area affected by S. tritici by potassium chloride was expected to lead to an increased yield. However, no significant increases in grain yield, 1000‐grain weight or specific weight were observed compared with untreated plots.…”

Section: Discussionmentioning

confidence: 99%

Effect of foliar‐applied potassium chloride on septoria leaf blotch of winter wheat

2004

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The effect of foliar-applied potassium chloride on Septoria tritici , the anamorph of Mycosphaerella graminicola , was quantified and possible modes of action investigated during controlled-environment and field experiments. A field experiment in harvest year 1997 showed c . 50% reduction in the area of leaf 2 of winter wheat plants affected by septoria leaf blotch after foliar application of potassium chloride, compared with untreated controls. Similarly, in harvest year 1998 potassium chloride reduced, by about one-third, the area of the flag and penultimate leaf affected by S. tritici . However, a significant yield increase was not observed, although grains m − 2 did show an increase of borderline significance.Applications of epoxiconazole reduced the area of leaf 4 affected by S. tritici compared with untreated controls, whereas applications of chlorothalonil, potassium chloride or polyethylene glycol proved ineffective against disease development. This may suggest that potassium chloride is relatively immobile and possesses contact activity similar to that of chlorothalonil. In 1998, similar reductions in leaf area affected were observed with the inert osmoticum polyethylene glycol in the field, suggesting that the control provided by potassium chloride may be achieved by adverse osmotic effects on the pathogen. Scanning electron microscopy of germinating conidia on wheat plants showed inhibition of conidial germination by both potassium chloride and polyethylene glycol at the same calculated osmotic potential on the leaf surface.

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Section: Discussionmentioning

confidence: 99%

Effect of foliar‐applied potassium chloride on septoria leaf blotch of winter wheat

2004

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“…Fungicides application is effective to control SLB and their benefits have been long acknowledged, but they are not always timely applied, environmentally sound, or economically viable (Paveley et al, 1997). Timing and number of fungicide applications are crucial in crop protection strategy.…”

Section: Introductionmentioning

confidence: 99%

Estimating grain yield losses caused by septoria leaf blotch on durum wheat in Tunisia

Berraies

Gharbi

Rezgui

et al. 2014

Chilean J. Agric. Res.

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Septoria leaf blotch (SLB), caused by Zymoseptoria tritici (Desm.) Quaedvlieg & Crous, 2011 (teleomorph: Mycosphaerella graminicola (Fuckel) J. Schröt.), is an important wheat disease in the Mediterranean region. In Tunisia, SLB has become a major disease of durum wheat (Triticum turgidum L. subsp. durum [Desf.] Husn.) particularly during favorable growing seasons where significant yield losses and increase of fungicides use were recorded over the last three decades. The objectives of this study were to evaluate the effect of SLB severity on grain yield of new elite durum wheat breeding lines and to measure the relative effect of fungicide control on grain yield. Experiments were conducted during 2007-2008 and 2008-2009 cropping seasons. A set of 800 breeding lines were screened for reaction to SLB under natural infection at Béja research station. To estimate the disease effect, correlation between disease severity at early grain filling stage and grain yield was performed. Results showed that susceptible varieties yield was significantly reduced by SLB. Average yield reduction was as high as 384 and 325 kg ha -1 for every increment in disease severity on a 0-9 scale in both seasons, respectively. A negative correlation coefficient varied between -0.61 and -0.66 in both seasons. Treated and untreated trials conducted during 2008-2009 and 2009-2010 showed that yield of treated plots increased by 50% on the commonly cultivated susceptible varieties. The results of this investigation suggested that septoria incidence is related to large grain yield losses particularly on susceptible high yielding cultivars. However, appropriate fungicide application at booting growth stage could be beneficial for farmers. The development and use of more effective fungicide could be sought to alleviate the disease effects and therefore could be considered as a part of the integrated pest management and responsible use strategy on septoria leaf blotch in Tunisia.

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“…Firstly, the number of fungicide sprays remains the same, but only a fraction of the recommended field dose is applied at each spray. This is typical in the UK ( Paveley, 1994; Paveley et al ., 1997 ). Second, many small doses may be applied sequentially, causing fungicide to be present over a much longer period.…”

Section: Introductionmentioning

confidence: 70%

The effect of dose and mobility on the strength of selection for DMI fungicide resistance in inoculated field experiments

Metcalfe

Shaw

Russell³

2000

Plant Pathology

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Plots of spring wheat cv. Baldus were inoculated at GS 13 with four Mycosphaerella graminicola isolates, two relatively susceptible and two relatively resistant to DMI fungicides. Changes in the ratio of relatively susceptible to resistant types following fungicide or water sprays were measured. Three fungicides were compared: flutriafol, which is very mobile within leaves, fluquinconazole, which is less so, and prochloraz, which is almost immobile. All are inhibitors of sterol demethylation. In 1996, fungicide-treated plots were sprayed once with half the recommended dose at GS 39±47. In 1997, three doses were used: one-quarter and one-eighth of the recommended dose and a dual application of two one-eighth recommended doses, a week apart. Isolates were classified using a discriminating dose assay and the ratio of relatively susceptible to relatively resistant isolates in each field plot before and after fungicide application calculated. In both years, the numbers of relatively susceptible and relatively resistant isolates were equal just before fungicide application. All fungicides caused significant selection towards resistance, but the strength of selection varied with fungicide, dose and position in the crop canopy. Fluquinconazole selected most strongly and gave the best control of disease. Interactions between fungicide and dose were not significant. Selection was equally strong all along leaves sprayed with prochloraz, but increased smoothly from base to tip of leaves sprayed with fluquinconazole or flutriafol. Averaged over fungicides, reducing the dose of a single fungicide application from onequarter to one-eighth slightly reduced selection towards resistance on both leaf layers. The dual one-eighth dose caused twice the change of the single one-eighth dose on the flag leaf, but was similar to a single spray on leaf 2.

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Determinants of Fungicide Spray Decisions for Wheat

Cited by 31 publications

References 13 publications

Effect of foliar‐applied potassium chloride on septoria leaf blotch of winter wheat

Effect of foliar‐applied potassium chloride on septoria leaf blotch of winter wheat

Estimating grain yield losses caused by septoria leaf blotch on durum wheat in Tunisia

The effect of dose and mobility on the strength of selection for DMI fungicide resistance in inoculated field experiments

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