Horseradish: (A) Normal; (C) Internal Discoloration

Horseradish is a root plant from the mustard family. The root is harvested in the spring and fall and is sold to processors who grate the root, releasing the oils that distinguish horseradish from all other flavors. The oil creates a hot and spicy flavor. Consumers expect horseradish to be a light color. Internal discoloration of horseradish roots is the main production problem. Internal discoloration of the root begins with dark brown to black discoloration of the vascular system and gradually spreads to the core and cortex areas in the root. Internally discolored horseradish roots are useless for industrial purposes such as preparing horseradish sauce. Research has shown that fungicides can prevent the discoloration.

“Illinois produces approximately half of the total commercial horseradish in the United States. Over the past years, horseradish growers have experienced internal discoloration in horseradish roots, causing up to 100% yield losses.  …Fungicide fludioxonil (Maxim 4FS or Maxim Potato WP) and biofungicides Trichoderma virens (G-41/ABM 127 or SoilGard 12 G) and Bacillus subtilis (Serenade MAX), applied to pathogen-free sets, protected horseradish roots against the soil-borne pathogens for approximately 12 weeks. …Application of either the fungicide or one of the biofungicides to the tissue culture-generated sets protects roots in the field through July. The remaining period of the growing season is not long enough for infection and discoloration of the roots.”

Author: Babadoost, M.
Affiliation: Department of Crop Sciences, University of Illinois, Urbana.
Title: Set treatment for controlling internal discoloration of horseradish root.
Source: Phytopathology. 2006. 96[6](Supplement):S7