Position of inoculum in the canopy affects the risk of septoria tritici blotch epidemics in winter wheat

A - Papers appearing in refereed journals

Lovell, D. J., Parker, S. R., Hunter, T., Welham, S. J. and Nichols, A. R. 2004. Position of inoculum in the canopy affects the risk of septoria tritici blotch epidemics in winter wheat. Plant Pathology. 53 (1), pp. 11-21.

AuthorsLovell, D. J., Parker, S. R., Hunter, T., Welham, S. J. and Nichols, A. R.
Abstract

The spread of septoria leaf blotch in wheat caused by Mycosphaerella graminicola is widely reported to depend on the occurrence of splashy rainfall. Previous studies have also implicated an important effect of canopy architecture on the risk of disease spread. This is because architecture affects the proximity of the yield-forming leaves to inoculum present on older diseased leaves within the crop. This study demonstrated that infection of the final three leaves of winter wheat could occur in the absence of splashy rainfall. For cvs Riband and Longbow, the final two leaf layers emerged at a position approximate to 8 cm below older leaves containing sporulating lesions. Under these conditions, infection of new leaves occurred in treatments that simulated dew and nonsplashy rainfall. These treatments resulted in disease incidences of 10-40% above the untreated control on the final two leaf layers. Within a season, the distance between diseased and healthy leaves during the period of stem extension varied substantially across a range of 30 cultivars. While the magnitude of these differences was not the same across seasons, the relative differences between cultivars were generally consistent, suggesting a strong genotype influence on lesion proximity. This study shows how knowledge of the distribution of lesion proximity within a crop can be used to estimate the risk of inoculum transfer for a given maximum splash height. A rapid crop-monitoring method for estimating the distribution of lesion proximity was developed and tested. Lesion proximity was manipulated by plant growth regulator (PGR) treatments. Significant increases in disease, between 14 and 62%, were observed on the upper canopy leaves of plants treated with PGR. The largest differences were observed in treatments where lesion proximity was most affected.

KeywordsAgronomy; Plant Sciences
Year of Publication2004
JournalPlant Pathology
Journal citation53 (1), pp. 11-21
Digital Object Identifier (DOI)doi:10.1046/j.1365-3059.2003.00939.x
Open accessPublished as non-open access
Funder project or code422
505
445
513
ISSN00320862
PublisherWiley

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