Variations in soil characteristics affecting the occurrence of Aphanomyces root rot of sugar beet – Risk evaluation and disease control

• Published in: Soil biology & biochemistry Vol. 43; no. 2; pp. 316 - 323
• Main Authors: Olsson, Å., Persson, L., Olsson, S.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Ltd 01-02-2011; Elsevier
• Subjects: Agronomy. Soil science and plant productions; Aphanomyces; Aphanomyces cochlioides; beets; Beta vulgaris; bioassays; Biochemistry and biology; Biological and medical sciences; calcareous soils; Calcium; Chemical, physicochemical, biochemical and biological properties; clay fraction; Clay mineralogy; damping off; disease control; disease incidence; disease severity; Earth and Related Environmental Sciences; electrical conductivity; Fundamental and applied biological sciences. Psychology; geographical variation; Geologi; Geology; Geovetenskap och miljövetenskap; illite; kaolinite; Natural Sciences; Naturvetenskap; Physics, chemistry, biochemistry and biology of agricultural and forest soils; plant pathogenic fungi; risk assessment; root rot; Root rot potential; smectite; soil fertility; soil pH; Soil science; spatial variation; Sugar; sugar beet; Sugar beets; vermiculite; Sweden; Europe, Scania; Sugar beets; Aphanomyces cochlioides; Calcium; Clay mineralogy; Root rot potential; Stramenopila; Plant pathogen; Disease; Root; Property of soil; Mineralogical composition; Risk analysis; Oomycota; Root rots; Clay minerals; Sugar beet; Soil science
• ISSN: 0038-0717; 1879-3428
• DOI: 10.1016/j.soilbio.2010.10.017

Damping off and chronic root rot of sugar beet caused by Aphanomyces cochlioides is a major constraint in cultivation of sugar beet, with occurrence of the disease in Sweden being concentrated to specific areas. This study examined soil factors that can be used for risk assessment of Aphanomyces root rot. Soils from 134 field plots were assessed over three years for Aphanomyces root rot potential in bioassays and analysed for easily measured soil factors such as soluble nutrients, pH and soil electrical conductivity (EC). Classification of the field plots into four groups with increasing disease severity index (DSI) according to the bioassay revealed that the group with the lowest DSI (<39) had an average soil calcium (Ca) content of 430 mg/100 g and a soil EC of 1.12 mS/cm, which were significantly higher than in the groups with DSI >40. From these results, we concluded that soil Ca concentration is an easily measured factor that can be used to identify soils with an increased risk of Aphanomyces root rot. We suggest that the Ca content should be above 250 mg Ca/100 g soil to avoid problems with Aphanomyces root rot in sugar beet. To gain a more thorough understanding of the geographical variation in Aphanomyces root rot and its connection to the geological origin of the soils, a number of other soil factors were analysed in the field plots, including clay mineralogy, CEC, and particle size distribution. Aphanomyces root rot was very rare in soils with a high proportion of smectite and vermiculite relative to illite and kaolin minerals, here predominantly calcareous soils developed on clay till in south-western Scania.
► Soils conducive to Aphanomyces root rot are characterised by low amounts of Calcium. ► Aphanomyces root rot was rare in soils with smectite/vermiculite minerals. ► Ca content above 250 mg Ca/100 g soil reduces problems with Aphanomyces root rot. ► Soil EC was negatively correlated to DSI in the soils. ► Measurement of soil EC may be a tool for risk assessment of Aphanomyces root rot.