Evaluation of calcium cyanamide and liming for control of clubroot disease in cauliflower

The effects of six control strategies involving calcitic lime, hydrated lime, calcitic limestone dust and a granular form of calcium cyanamide were evaluated on a cauliflower crop during a 2-year field study. Prior to the first growing season, fall applications of 5 and 25 t ha−1 of calcitic lime broadcast were made. In the first growing season, only pre-planting application of hydrated lime and calcium cyanamide successfully reduced disease indices and increased yields. Post-planting application of calcium cyanamide, and post-harvest application of calcitic lime the preceding year were ineffective. In the second growing season, the best clubroot control results were obtained with the finest lime materials (hydrated lime, calcitic limestone dust) and the preceding post-harvest intensive liming treatment. Successful treatments raised pH from 5.7 to 7.0 in the first season and from 6.7 to 7.4 in the second season. The high cost of using calcium cyanamide was reduced by means of band application along the transplant rows.