Contributions of disease resistance and escape to the control of septoria tritici blotch of wheat

Abstract

The contributions of disease escape and disease resistance to the responses of wheat to septoria tritici leaf blotch (STB) were analysed in a set of 226 lines, including modern cultivars, breeding lines and their progenitors dating back to the origin of scientific wheat breeding. Field trials were located in the important wheat-growing region of eastern England and were subject to natural infection by Mycosphaerella graminicola. STB scores were related to disease-escape traits, notably height, leaf spacing, leaf morphology and heading date, and to the presence of known Stb resistance genes and isolate-specific resistances. The Stb6 resistance gene was associated with a reduction of 19% in the level of STB in the complete set of 226 lines and with a 33% reduction in a subset of 139 lines of semidwarf stature. Greater plant height was strongly associated with reduced STB in the full set of lines, but only weakly in the semidwarf lines. Shorter leaf length was also associated with reduced STB, but, in contrast to earlier reports, lines with more prostrate leaves had more STB on average, probably because they tended to have longer leaves. Several lines, notably cvs Pastiche and Exsept, had low mean levels of STB which could not be explained by either escape traits or specific resistance genes, implying that they have unknown genes for partial resistance to STB.

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

“…In spite of continued efforts to develop cultivars with either disease escape traits or specific resistance genes (Arraiano et al 2009), the lack of highly resistant cultivars means that fungicide use is currently the only effective method to control SLB. Taking into account the complexity and variability of the progress of the disease (Parsons and te Beest 2004), multiple decision support systems have been developed in an attempt to manage fungicide applications as effectively as possible (Burke and Dunne 2008).…”

Septoria Leaf Blotch and Yellow Rust Control By: Fungicide Application Opportunity and Genetic Response of Bread Wheat Varieties

“…The strategies to control both fungi include cultural practices (crop rotation, use of balanced fertilizers, framework of planting dates), use of resistant varieties and fungicide application. Despite of continued efforts to develop cultivars with either disease escape traits or specific diseases resistance genes, fungicides are, currently, the only effective method for controlling these pathogens (Arraiano et al, 2009). The generalized use of chemicals, the harmful effects concerning the environment (pollution on groundwater sheets, negative impact on flora and fauna), the high application costs and the ability of the pathogens to develop characteristics related with several infectious cycles and the realization of a sexual reproduction, causing resilience to its active substances, in particular to triazoles and other demethylation-inhibitors (Ashby, 2011), reducing their efficacy.…”

Modified plant architecture to enhance crop disease control: genetic control and possible value of upright fruit position in cucumber

“…Increased distance from the rain splash zone has been associated with reduced disease severity for soybean rust Phakopsora pachyrhizi (Schmitz and Grant 2009) and for several diseases in wheat including Fusarium head blight, tan spot, and septoria leaf blotch (e.g., Arraiano et al 2009;Fernandez et al 2002;Srinivasachary Gosman et al 2008). In studies using a set of 226 wheat lines to differentiate between factors conferring disease resistance rather than avoidance, a strong correlation was observed between increased plant height and reduced Septoria tritici infection (Arraiano et al 2009). While avoidance of P. capsici by trellising of cucumber is not economically feasible in most production schemes, breeding for a plant habit that reduces contact with the pathogen might facilitate disease control without incurring additional labour costs.…”

“…In wheat, a large number of studies have associated dwarf plant-type with increased Fusarium head blight (Fusaiurm graminarium) occurrence, especially initial infection (type I resistance) (e.g., Srinivasachary Gosman et al 2008;Klar et al 2007). Decreased plant height also was correlated with increased infection by Septoria tritici and tan spot (Pyrenophora tritici-repentis) diseases of wheat, likely due to increased contact with rain splashing from the soil or more dense canopy structure (Fernandez et al 2002;Arraiano et al 2009). A different type of architectural avoidance was observed in corn with respect to Fusarium ear rot (Fusarium moniliforme); cultivars with tight corn husks reduced the ability of the thrips vector to feed on the developing corn kernels and spread disease (Warfield and Davis 1996).…”