Local dispersal of Puccinia striiformis f. sp. tritici from isolated source lesions

Abstract

Understanding how disease foci arise from single source lesions has not been well studied. Here, single wheat leaves were inoculated with Puccinia striiformis f. sp. tritici urediniospores, and all wheat leaves within two intersecting 0.3 × 3.0 m transects were sampled in eight replicates over three years. The lesions observed on each of the top three leaves on plants within 1.5 m from the source lesion were three-dimensionally mapped. The total number of lesions within a 1.5 m radius was estimated by dividing the number of lesions observed within each 0.025 m-wide annulus by the fraction of the annulus sampled. The estimated total number of lesions produced within 1.5 m of a single source lesion ranged from 27 to 776, with a mean of 288 lesions. Eighty percent of the lesions were recorded within 0.69 m of the source infection. The proportion of total lesions observed at a given distance from the source was fitted well by the Lomax and Weibull distributions, reflecting the large proportion of lesions arising close to the source, and when fitted to an inverse-power distribution had a slope (b) of 2.5. There were more lesions produced on leaves higher in the canopy than on lower leaves, with more lesions being detected above than below the point of inoculation. Simultaneous measurement of lesion gradients and spore dispersal in the final year of the study suggests that this pattern is due to greater susceptibility of upper leaves, rather than increased dispersal to upper leaves.

Dispersal, host genotype and environment shape the spatial dynamics of a parasite in the wild

“…Tack, personal observation). Likewise, Farber et al (2017) demonstrated that in the wheat stripe rust Puccinia striiformis f. sp. tritici, eighty percent of the new lesions appeared within 0.69 meter from the infection source.…”

“…, Farber et al. ), and few studies are available from natural systems. Third, while dispersal is a central life‐history trait (Kokko and López‐Sepulcre ), we lack direct assessments of the dispersal and colonization ability of wild parasites (Zheng et al.…”

“…Nonetheless, the majority of the experimental studies have been restricted to a small spatial scale (Jessup et al 2004, G omez and Buckling 2011, Tack et al 2014, whereas the persistence of many species may depend on landscape-level processes (Hanski 1999). As a second limitation, many studies have focused on laboratory (Boots andMealor 2007, Vogwill et al 2009) or agricultural and forestry systems (McNew 1960, Mullett et al 2016, Farber et al 2017, and few studies are available from natural systems. Third, while dispersal is a central life-history trait (Kokko and L opez-Sepulcre 2006), we lack direct assessments of the dispersal and colonization ability of wild parasites (Zheng et al 2015, Becheler et al 2016.…”

Dispersal kernels may be scalable: Implications from a plant pathogen

“…(a) Extent of each spatial scale. (b) Detail of the local (Farber et al, ) dispersal study, extending to 1.524 m, (c) field‐wide (Sackett & Mundt, ) dispersal study, extending to 91.44 m, and (d) regional (Kingsolver et al, ) dispersal study, extending to 10.6 km…”

Distinguishing sporulating and nonsporulating lesions as a method for evaluating the resistance of sugarcane genotypes to orange rust

“…Even studies of dispersal of Puccinia striiformis f. sp. tritici have adopted a lesion count rather than measures of disease severity (Farber et al ., ).…”