Influence of nitrogen on the development of Septoria epidemics in winter wheat

Leitch, M. H.; Jenkins, P. D.

doi:10.1017/s0021859600073329

Cited by 61 publications

(66 citation statements)

References 17 publications

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“…In common with other studies comparing Napplication rates in winter wheat (Prew et al, 1983;Leitch & Jenkins, 1995), we found least disease on the crops receiving least N. Previous reports have suggested that this is because low-N crops become senescent more rapidly, so that green leaf area (GLA) becomes limiting on disease progress. However, our study suggested that S. tritici was responsible for most of the senescence recorded in both high-and low-N treatments.…”

Section: Effect Of Crop Husbandry On Disease Progresssupporting

confidence: 89%

**Influence of crop growth and structure on the risk of epidemics by Mycosphaerella graminicola (Septoria tritici) in winter wheat**

et al. 1997

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Generally, it is recognized that inocula of Septoria tritici present on the basal leaves of winter wheat crops are spread towards the top of the canopy by splashy rainfall. This mechanism of inoculum dispersal is commonly accepted to be a key limit on disease progression. Therefore, attempts to forecast epidemics of S. tritici often quantify rainfall by some means, but largely ignore measurement of pathogen and host variables. In the present study, we show that new wheat leaves emerge initially at a height below established leaves that can contain sporulating lesions of S. tritici. This presents the possibility of horizontal inoculum transfer, even without splashy rainfall. The extent and duration of overlap between emergent and established leaves was found to differ considerably with cultivar and sowing date. Nitrogen application had little effect on overlap, because differences in crop phenology, e.g. leaf area and nodal length, were relative. However, estimates of raindrop penetration to the base of crop canopies suggested that vertical movement of inoculum is affected by nitrogen application. Crops receiving more nitrogen are denser, and therefore less rainfall reaches the base of the canopy. The interactions between crop and pathogen development are discussed with reference to the implications for predicting disease risk. In particular, cultivar traits that promote disease escape are quantified.

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Section: Effect Of Crop Husbandry On Disease Progresssupporting

confidence: 89%

**Influence of crop growth and structure on the risk of epidemics by Mycosphaerella graminicola (Septoria tritici) in winter wheat**

et al. 1997

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“…In 2001, fungicide application again failed to produce yield increase at low N rate (Table 4) because of small overall disease severity in both sprayed (4.6 %) and untreated plots (2.5 %). Lower incidence of foliar diseases under less intensive N fertilization has been reported by several authors (Guy and Oplinger 1989, Leitch and Jenkins 1995, Olesen et al. 2003).…”

Section: Resultssupporting

confidence: 58%

Winter Wheat Cultivar Responses to Fungicide Application are Affected by Nitrogen Fertilization Rate

Varga¹,

Svečnjak²,

Maćešić³

et al. 2005

J Agronomy Crop Science

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Foliar fungicides are important management inputs for winter wheat (Triticum aestivum L.) in high-yielding areas of Europe, but their effectiveness may interact with cultivar selection and nitrogen (N) fertilization. No information is available on the potential use of fungicides in reducing yield losses from foliar diseases in Croatia, where wheat crop is extensively grown under low N inputs. Field experiments were conducted during 2000-02 to evaluate the agronomic responses of six winter wheat cultivars to fungicide application (tebuconazol around heading) compared with untreated plots at low (67 kg N ha )1 ) and high (194 kg N ha )1 ) N fertilization rates. Grain yields tended to increase in all years following fungicide treatment at high N rate by an average of 10.1 % (773 kg ha )1 ), but improved significantly in one year only at low N rate. When these occurred, yield increases were associated with larger grain weight per ear primarily due to heavier 1000-kernel weight. Cultivars differed in their responses to fungicide application across growing seasons and N fertilization rates. Under low disease pressure in 2000 and 2001, improved yields with fungicide use occurred for few susceptible cultivars only, whereas all cultivars significantly increased yields under higher disease severity in 2002 by an average of 383 kg ha )1 (5.0 %) at low N rate and 1443 kg ha )1 (19.0 %) at high N rate. Following fungicide application at high N rate, some susceptible cultivars outyielded resistant cultivars, whereas opposite responses occurred in untreated plots. High N fertilization rate consistently produced larger grain yields except under high disease severity and no fungicide sprayed in 2002, when it had no benefits at all over low N rate. Fungicide application showed limited importance for wheat performance at low N rate; however, cultivars significantly differed in yield responses as well as in rankings after fungicide use at high N fertilization rate.

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“…Mechanisms suggested in the literature from studies on a range of pathosystems include changes in biochemical processes in the plant, such as a decrease in the content of phenol with an increase of N application (Király, 1964), changes in crop canopy structure (Tompkins et al ., 1992), or a favourable microclimate as a result of increased crop density and canopy size (Darwinkel, 1980; Oerke & Schönbeck, 1990; Bryson et al ., 1995; Danial & Parlevliet, 1995; Leitch & Jenkins, 1995; Jensen & Munk, 1997). For powdery mildew development on wheat, leaf N content was found to be more important than canopy size (Olesen et al ., 2003b).…”

Section: Introductionmentioning

confidence: 99%

Nitrogen per unit leaf area affects the upper asymptote ofPuccinia striiformisf.sp.triticiepidemics in winter wheat

et al. 2004

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Field trials tested which components of epidemic development of Puccinia striiformis , the cause of yellow rust, were affected by nitrogen (N) fertilizer applied to winter wheat. Both timing and amount of N were varied to affect canopy size and leaf N content, and to provide a supply of mobile N to the pathogen, by causing fresh N uptake after leaf expansion was complete. No N was applied to control plots. A logistic disease-progress function was fitted to disease-severity data, which were assessed in absolute units. Leaf area and specific leaf N (g N per m 2 leaf tissue) were quantified. Large and highly significant effects of N on the upper asymptotes, or 'carrying capacities' ( c ) were found. Effects on rates and points of inflection of the epidemics were not significant. Early N resulted in larger shoot numbers and leaf area, but disease was also more severe, so that by grain filling, the remaining green leaf areas were larger without N than with N. Later N treatments did not increase canopy size, but did increase symptom area compared with the control. These effects differ from the concept that N affects disease as a result of its effect on canopy growth, and therefore canopy microclimate, and suggest instead a substrate effect. Linear regression revealed that 51% of the observed differences in c were explained by variation in specific leaf N, suggesting that growth of the rust fungus may depend directly on particular components of total leaf N.

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Influence of nitrogen on the development of Septoria epidemics in winter wheat

Cited by 61 publications

References 17 publications

**Influence of crop growth and structure on the risk of epidemics by Mycosphaerella graminicola (Septoria tritici) in winter wheat**

**Influence of crop growth and structure on the risk of epidemics by Mycosphaerella graminicola (Septoria tritici) in winter wheat**

Winter Wheat Cultivar Responses to Fungicide Application are Affected by Nitrogen Fertilization Rate

Nitrogen per unit leaf area affects the upper asymptote ofPuccinia striiformisf.sp.triticiepidemics in winter wheat

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