European Journal of Plant Pathology

, Volume 102, Issue 2, pp 205–207 | Cite as

Threshold values for chemical control of powdery mildew (Erysiphe cruciferarum) on Brussels sprouts

  • P. D. de Jong
  • G. A. Hasper
Short Communications


To establish control thresholds for chemical control of powdery mildew (Erysiphe cruciferarum) on Brussels sprouts, mildew intensity on leaves and buds was observed on the cultivars Lunet, Tardis and Asgard during three years in unsprayed plots. Mildew infection on the leaves was observed from late August onwards, increasing to moderate or high levels. In one year light infestation of the buds was observed, but no reduction in quality occurred. These preliminary results indicate, that from late August onwards the following levels of leaf injury by powdery mildew can be tolerated: T=5+0.42*(Julian date — 235), in which T is the tolerable leaf injury in percentage leaf area covered. When sampling the crop to assess powdery mildew infection, care must be taken that leaves are sampled from all stem positions, as top leaves tend to be much less infected.

Key words

Brassica oleracea supervised control vegetables 


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Copyright information

© Kluwer Academic Publishers 1996

Authors and Affiliations

  • P. D. de Jong
    • 1
  • G. A. Hasper
    • 1
  1. 1.Research Institute for Plant ProtectionIPO-DLOGW WageningenThe Netherlands

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