Economics of a decision–support system for managing the main fungal diseases of winter wheat in the Grand-Duchy of Luxembourg

Abstract

a b s t r a c tWe evaluated the cost effectiveness of a decision-support system (DSS) developed for assessing in real time the risk of progression of the main fungal diseases (i.e., Septoria leaf blotch, powdery mildew, leaf rusts and Fusarium head blight) of winter wheat in the Grand-Duchy of Luxembourg (GDL). The study was conducted in replicated field experiments located in four agricultural locations (representative of the main agro-ecological regions of the country) over a 10-year period (2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012). Three fungicide spray strategies were compared: a single DSS-based system and two commonly used spray practices in the GDL, a double-(2T) and a triple-spray (3T) treatment; there was also a non-treated control. In years with a high disease pressure, the DSS-based recommendation resulted in protection of the three upper leaves comparable to that achieved with the 2T and 3T treatments, with significant grain yield increases (P > 0.05) compared to the control (a 4 to 42% increase, depending on the site and year). Overall, the financial gain in treated plots compared with the control ranged from 3 to 16% at the study sites. Furthermore, in seasons when dry weather conditions precluded epidemic development, the DSS recommended no fungicide spray, reducing use of fungicide, and thus saving the cost of the product. The gain in yield for the 2T and 3T plots (compared with control) did not necessarily result in a financial gain during the duration of the experiment. This study demonstrates the potential advantages and profitability of using a DSS-based approach for disease management.

Do single, double or triple fungicide sprays differentially affect the grain quality in winter wheat?

“…(Table 3). High GDDs in June can accelerate the leaf senescence process and thus reduce the grain filling period, which occurs in June at the experimental sites (El Jarroudi et al, 2012b).…”

“…Nitrogen fertilization, a practice known to have influence on grain quality parameters (Ruske et al, 2004), was split as follows: all plots received 40-70 kg N ha −1 , in the form of ammonium nitrate, at growth stage (GS) 25 (main shoot and 5 tillers; Zadoks et al, 1974), followed by 60-70 kg N ha −1 at GS32 (second node detectable), and a final application of 65-95 kg N ha −1 at GS59 (emergence of inflorescence completed). During the 4-year period, three fungicide treatments were compared at each site: a single application (1T) based on a decision support system (El Jarroudi et al, 2015), a double (2T) and a triple (3T) spray application, alongside control plots (0T). The fungicides used, along with the growth stage at which they were applied are reported (Table 2).…”

“…Common wheat quality parameters include protein content and quality, specific weight, grain hardness, thousand grains weight, Hagberg falling number, moisture content, sedimentation volume and foreign contaminants. Wheat is typically milled into flour which is used to make a wide range (El Jarroudi et al, 2012b). Beyond reducing yield, Fusarium species reduce the quality by release of toxic secondary metabolites in the grain and by modifying the amino acid profile of winter wheat (Beyer and Aumann, 2008).…”

“…Nonetheless, preventive fungicide applications are needed to protect winter wheat crops from fungal disease, particularly on the three upper leaves that contribute the most to the final yield; generally two to three foliar fungicide treatments are applied during the cropping season. With the potential environmental damage caused by overand/or misuse of agrochemicals in protecting winter wheat against fungal diseases, warning bulletins based on a decision support system (DSS; PROCULTURE and add-ons; El Jarroudi et al, 2009Jarroudi et al, , 2014Jarroudi et al, , 2015, and available from various websites (for example, http:// www.centralpaysanne.lu, http://www.agrimeteo.lu, http://www. lwk.lu/mediathek), have been issued weekly throughout the growing season in Luxembourg for the last decade, in order to provide farmers with information regarding disease risk, the need to spray fungicides, the optimum timing, and thus control fungal diseases in a profitable and more environmentally friendly way (El Jarroudi et al, 2013.…”

“…In further experiments, El Jarroudi et al (2015) reported that a double or triple fungicide treatment (using mixes of strobilurins and triazoles) did not necessarily increase the financial return compared to a single fungicide treatment due to only mild diseases severities developing on the three upper leaves during grain development. Additionally, in years with no severe fungal disease, the double and/or triple fungicide treatment could be avoided entirely when following the recommendations of the decision support system (El Jarroudi et al, 2015). In order to gain more insights to minimizing and optimizing fungicide applications, we asked the question: does a double or triple fungicide treatment significantly improve the quality of winter wheat grain compared with a single, judiciously applied fungicide spray (i.e., determined through a decision support system) as the single fungicide application is aimed to maximize disease control while minimizing potential harmful impacts on the environment thus, providing the grower with sustainable financial returns?…”