Survival, dispersal, and primary infection site for Cercospora beticola in sugar beet

J. Khan, L. E. Del Rio, R. Nelson, V. Rivera-Varas, G. A. Secor, M. F.R. Khan

Research output: Contribution to journalArticlepeer-review

50 Scopus citations

Abstract

Cercospora beticola survives as stromata in infected crop residue. Spores produced on these survival structures serve as primary inoculum during the next cropping season. This study was conducted to determine how long C. beticola can survive at different soil depths, the mechanism of inoculum dispersal, and the primary infection site in sugar beet. Longevity of C. beticola was studied over a 3-year period under field conditions at Fargo, ND. C. beticola-infected leaves were placed at depths of 0, 10, and 20 cm and retrieved after 10, 22, and 34 months. Survival of C. beticola inoculum declined with time and soil depth. Inoculum left on the soil surface, 0 cm in depth, survived the longest (22 months) compared with that buried at 10 cm (10 months) and 20 cm (10 months). C. beticola dispersal from the primary source of inoculum was studied in the field for three growing seasons. Sugar beet plants were surrounded with plastic cages with and without ground cover, or exposed with and without ground cover. Significantly higher disease severity was observed on exposed plants than caged plants with or without ground cover, suggesting that wind was the major dispersal factor for C. beticola inoculum. The primary infection site by C. beticola was determined in a greenhouse study. Leaves, roots, and stems of healthy sugar beet plants were inoculated with C. beticola. Cercospora leaf spot symptoms were observed only on plants that were leaf inoculated, suggesting that the leaf was the primary infection site for C. beticola.

Original languageEnglish (US)
Pages (from-to)741-745
Number of pages5
JournalPlant disease
Volume92
Issue number5
DOIs
StatePublished - May 2008
Externally publishedYes

Keywords

  • Beta vulgaris
  • Epidemiology
  • Residue degradation

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