Plant Pathology (1997) 46, 939-945

S. Salamati and H.A. Magnus (1997)
Leaf blotch severity on spring barley infected by isolates of Rhynchosporium secalis under different temperature and humidity regimes
Plant Pathology 46 (6), 939-945
Abstract: The infection efficiency and severity of leaf blotch on spring barley inoculated with three pathotypes of Rhynchosporium secalis from central Norway were studied under different temperature and humidity regimes. Seedlings of the cultivar Arve were subjected to two constant temperatures, 13° or 18°C. Dry periods of 8 h or longer before or after a wet period of 4 h, carried out in the first 48 h postinoculation, reduced disease severity assessed 16 days after inoculation. The effect of dry periods of up to 24 h was nullified when plants were subjected to high humidity for 48 h after the dry treatment. The disease developed most rapidly when the wet period was 48 h and the temperature 18°C. At or near the optimum temperature for R. secalis (18°C), leaf wetness duration as short as 2 h resulted in considerable disease. Isolates reacted differently to temperature. The most aggressive isolate caused severe disease irrespective of temperature (56-70% of the leaf area infected); however, disease severity caused by the least aggressive isolate was significantly higher at the optimum temperature compared with a lower temperature (13°C). This information can facilitate evaluation of weather data in relation to predicting leaf blotch for advisory purposes.
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Research topic(s) for pests/diseases/weeds:
environment - cropping system/rotation
population dynamics/ epidemiology

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Rhynchosporium commune	Barley (Hordeum vulgare)	Norway