Verticillium wilt of cauliflower in Belgium.

Since several years commercial cauliflower in Belgium is severely affected by a vascular wilt disease. Plants wilt and a vascular discoloration of the cauliflower stems can be observed. The pathogen causes significant yield and quality losses. The first objective of this study was to isolate and characterise the causal agent of this disease. Verticillium species could be isolated out of the vascular tissue of symptomatic cauliflower plants. Morphological and physiological characteristics indicated that the isolates from cauliflower could be identified as the new and brassica-related species V. longisporum. Secondly, the susceptibility of several cauliflower cultivars to V. longisporum was evaluated by way of field experiments in naturally infested soil. At harvest, vascular discoloration was evaluated by a visual score. These experiments pointed to considerable differences between cultivars in their susceptibility to V. longisporum. The final goal of this study was to find a way to control the wilt disease on cauliflower. A field experiment showed that vascular discoloration of cauliflower was significantly reduced when soil was incorporated with broccoli residues, two Brassica green manures (B. juncea or B. nigra) or two commercial biological products based on Talaromyces flavus or Trichoderma sp..