Calcium cyanamide--an effective tool to control clubroot: a review
1996
Klasse, H.J.
The unique fertilizer calcium cyanamide allows the achievement of higher cabbage yields even on soils heavily infested with clubroot. It reduces the viability of resting spores of Plasmodiophora brassicae in the soil. To achieve best results, the following should be considered: 1. High soil humidity is necessary to release, dissolve and distribute hydrogen cyanamide, the fungicidal metabolite of calcium cyanamide, in the soil. This increases the percentage of resting spores which contact with cyanamide. Best results are obtained when calcium cyanamide is mixed into the soil and slight irrigation or rainfall follows thoroughly. 2. Efficacy is improved with increasing application rates. Depending on the crop demand for nitrogen, an application rate should be chosen which is as high as possible. 3. Cyanamide is quickly decomposed in soil; therefore, it gives mainly control of primary infections. As protection against clubroot is most important during the first growth stages, the waiting period between application and planting or sowing should be as short as possible, normally this means one to two weeks depending on dose rate and prevailing soil temperature. 4. To achieve a reduction of soil infestation by Plasmodiophora brassicae, crop rotation has to be combined with recurrent applications of calcium cyanamide.
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