Field testing of six decision support systems for scheduling fungicide applications to control Mycosphaerella graminicola on winter wheat crops in Ireland

Abstract

SUMMARYField experiments were conducted between 2003 and 2005 to compare the efficacy of five interactive decision support systems (DSSs) (DESSAC, PLANT-Plus, proPLANT Expert, CerDis and Crop Protection Online (CPO)) and an in-crop system (Septoria Timer) to schedule fungicide applications to winter wheat cultivars (Madrigal and Claire) for the control of Mycosphaerella graminicola. The effectiveness of the crop management programmes proposed by the DSSs was compared with that of standard 2-spray programmes applied at GS 37 and 65 and 3-spray programmes applied at GS 32, 39 and 65. Compared with the 3-spray programme, the programme scheduled by CPO advised application of the least active ingredient to the six trials over three seasons, while together with the Septoria Timer it also advised the least number of applications (average 2·3 per crop). The PLANT-Plus system advised the highest input of active ingredient and the highest number of applications (average of 4·0 per crop). The interactive DSSs responded to cultivar susceptibility to M. graminicola by scheduling more applications to the susceptible cv. Madrigal compared with the moderately resistant cv. Claire. Whether control of M. graminicola is expressed as reduction in the proportion of necrosis per leaf or a reduction of the area under the disease progress curve, the 3-spray programme provided the most effective control. The Septoria Timer provided a similar level of control. For the remaining programmes, the effectiveness of control varied with observation date, leaf and cultivar. The 2-spray programme provided the least successful control. Fungicide application significantly increased grain yield each season. The fungicide scheduling programme that provided the highest grain yield varied by cultivar and season. Grain specific weight was enhanced by fungicide application compared with the untreated control, except for cv. Claire in 2004. The fungicide scheduling programme that provided the highest specific weight varied with cultivar and season. The highest average margin over fungicide cost was provided by the Septoria Timer.