Integrated Foliar Disease Management to Prevent Yield Loss in Argentinian Wheat Production

Abstract

Zero tillage oft en leads to wheat (Triticum aestivum L.) yield losses from diseases caused by necrotrophic foliar pathogens. Th e aim of this work was to evaluate the combined eff ect of tillage, N fertilization, fungicides, and resistant cultivars in reducing foliar disease severity to prevent signifi cant yield losses. A 2-yr study including combinations of (i) conventional and zero tillage; (ii) N fertilization rates 0, 80, or 160 kg ha -1 N; (iii) two fungicide treatments (with and without a fungicide (1 L of metconazole, 9%) at growth stages (GS) 32 and 39; and (iv) three wheat cultivars was conducted in the Rolling Pampas region in Argentina. Th e most common foliar disease in the trial was tan spot [Pyrenophora tritici-repentis (Died.) Drechs.]. Conventional tillage reduced foliar disease severity at GS 23 by 46 and 56% and the area under disease progress curve (AUDPC) by 20 and 14% for each season, respectively compared with zero tillage. Th e cultivar Buck Bigua had signifi cantly lower AUDPC values than the others. Fungicide and N application reduced disease severity at GS 23 by 35 and 34% respectively, on average over both years. Disease was less severe in zero tillage plots which received a fungicide compared to conventional tillage plots that were not treated with fungicide. In 2002 yields were greater in conventional tillage plots with 160 kg ha -1 N and fungicide application than in all other treatments. In 2003 yields were greatest in zero tillage plots with 160 kg ha -1 N and fungicide. Th e results of this study indicate that in spite of the increase of necrotrophic diseases, developing no-till systems in wheat monoculture is possible without signifi cant yield losses if eff ective disease management practices are applied.

The effects of soil tillage and crop rotation on the development of winter wheat leaf diseases

“…Our results confirmed the importance of the level of primary inoculums in the development of tan spot. The significance of ploughing under wheat monoculture was observed in Argentina, where reduction of wheat debris by ploughing decreased the level of disease if the prevalent disease was tan spot (Simon et al, 2011). Both investigated factors -soil tillage systems and crop rotation -are important measures to control tan spot, but combinations of these two factors (reduced soil tillage and lack of crop rotation) significantly increase the risk of tan spot.…”

Distribution of races and Tox genes in Pyrenophora tritici-repentis isolates from wheat in Argentina

“…In Argentina, the disease has gained importance in most of the wheat field areas particularly under no-tillage (Moreno and Perelló 2010). Tan spot epidemics potentially reduce kernel weight, number of grains per spike and total biomass (Simón et al 2011), thus leading to reduced yield, but also grain quality may be affected (Fernandez et al 1994). Knowledge of pathogen variability is an important component for developing resistant cultivars (Araya 2003).…”

Recent Advances on Integrated Foliar Disease Management with Special Emphasis in Argentina Wheat Production

“…Simón et al [82,84,90] found that in conducive conditions, N fertilization increases the severity of Septoria leaf blotch and discussed the effect of different factors affecting the influence of N supply. Increasing N rates retarded tan spot development [66,69,73,91,92,93,94]. However, Bockus and Davis [95] suggested that N applications do not directly affect tan spot severity, but rather appear to reduce disease impact through delayed leaf senescence or that high N rates increase Septoria leaf blotch or tan spot severity due to an increase in crop biomass production, which creates a microenvironment conducive to fungal development in humid regions [82,84,85,96,97].…”

“…The increased yield resulted from increases in spikes.m -2 and thousand grain weight in two seasons, and also from grain.spike -1 in one season [94] (Table 2).…”