Spring air temperature accounts for the bimodal temporal distribution of Septoria tritici epidemics in the winter wheat stands of Luxembourg

Abstract

This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues.Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. The period between sowing and the point of time, when 50% of the leaf area was necrotized due to colonization by S. tritici (T 50 ) was estimated for each year, site, cultivar and leaf layer by non-linear regression. T 50 values followed a bimodal distribution with one maximum at 245 days after sowing (DAS; early epidemics) and one maximum at 270 DAS (late epidemics). Early epidemics were preceded by almost constant daily average temperatures of 13.2 AE 0.8 C between 181 and 210 DAS. Late epidemics were preceded by an approximately linear increase in temperature from 8.7 AE 0.9 to 12.1 AE 0.9 C during the same period of time. Based on these differences, it seems possible to predict whether an early or a late epidemic can be expected at least 35 days before the epidemic outbreak. Temperature sums calculated with a base temperature of 6.6 C starting at sowing and ending when T 50 was reached were not significantly different between early and late epidemics (P ¼ 0.73) and averaged 1721 AE 49 days. Fungicide applications, which resulted into a delay of the epidemic development similar to the difference between early and late epidemics, resulted in a yield increase between 11.7 and 12.6%.

Forecasting the breaching of the control threshold for Ceutorhynchus pallidactylus in oilseed rape

“…The significant differences detected between both temperature time series were tested (leave‐one‐out cross‐validation) for their ability to predict whether the control threshold for C. pallidactylus will be exceeded using the approach described by Beyer et al () for early and late fungal epidemics. Briefly, the temperature differences between the left‐out case and (i) the mean temperature of the cases where the control threshold was not exceeded and (ii) the mean temperature of the cases where the control threshold was exceeded were calculated for each day between day of year (DoY) 14–18 (14–18 January) and DoY 36–44 (5–13 February).…”

Influence of fungicide treatments on disease severity caused by Zymoseptoria tritici, and on grain yield and quality parameters of bread-making wheat under Mediterranean conditions

“…Fungicide timing is crucial to efficacy (Paveley et al 2000). If fungicide is applied too early, later infections will occur, and if they are applied too late, damage may already have occurred (Beyer et al 2012). The number of fungicide applications to control SLB range from 1-4 per crop (Ashby 2011), applied during the period from flag leaf emergence to ear emergence (GS37-59 of the Zadocks scale, Zadoks et al 1974).…”

Winter wheat leaf diseases and several steps included in their integrated control: A review

“…For example, the protection of wheat in Grand-Duchy of Luxembourg largely depends on early fungicide use before severe symptoms appear that can reduce grain yields. Beyer et al (2012) confirm that an early Z. tritici epidemic (about 245 days after sowing) is more devastating than late epidemics (epidemics around 270 days after sowing) and requires an accurate prognosis for early epidemics. The first spray is used during the period of stem elongation and is aimed to control early-season diseases, including powdery mildew and eyespot.…”

“…Early epidemics were preceded by almost constant average daily temperatures of 13.2 ± 0.8 °C between 181 and 210 days after sowing. Late epidemics were preceded by an approximately linear increase in temperature from 8.7 ± 0.9 to 12.1 ± 0.9 °C (Beyer et al, 2012). The mean latent period for seedlings was significantly shorter than that for adult plants (Suffert, & Thompson, 2018).…”