European Journal of Plant Pathology (2015) 142, 319-330

B. Hanse, E.E.M. Raaijmakers, A.H.L. Schoone and P.M.S. van Oorschot (2015)
Stemphylium sp., the cause of yellow leaf spot disease in sugar beet (Beta vulgaris L.) in the Netherlands
European Journal of Plant Pathology 142 (2), 319-330
Abstract: During the summer of 2007, a distinctive type of yellow leaf spot was observed for the first time in sugar beet (Beta vulgaris L.) in the Netherlands. In the following years a rapid spread over all regions of the Netherlands was reported. The infestation appears in June-August on the leaves of sugar beet and starts with small, irregular, yellow spots. Subsequently the yellow spots become necrotic from the centre of the lesion outward, with the tissue becoming brown (or brownish). The spots spread over the leaves and infest all the leaves of the plant. Due to the loss of leaves the size of the canopy declines and yield loss occurs. Research was conducted to identify the causal agent. Climate room trials with isolates obtained from infested sugar beet leaves showed that Stemphylium sp. was able to infest leaves of healthy growing sugar beet plants with brown spots, similar to the necrotic spots seen in the field. From the leaf spots in the climate room trials, Stemphylium sp. was re-isolated, according to Koch's postulates. Thus, it was confirmed that this Stemphylium sp. is a primary pathogen for sugar beet. In field trials of fungicide efficacy a sugar yield loss of up to 42 % (a financial yield loss of 51 %) was found. Field trials show that it is hard to control this Stemphylium sp. with the fungicides registered for sugar beet in the Netherlands and efficacy of control of Stemphylium sp. differs between fungicides with active ingredients belonging to the same chemical class. In addition to sugar beet, potato (Solanum tuberosum L.), white mustard (Sinapsis alba L.), red beet (Beta vulgaris L.), spinach (Spinacia oleracea L.) and fat hen (Chenopodium album L.) were identified as hosts in an assay of plants grown and inoculated in climate rooms.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Bram Hanse

Research topic(s) for pests/diseases/weeds:
general biology - morphology - evolution

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Stemphylium (anamorphic genus)	Beet/sugarbeet (Beta vulgaris)	Netherlands