Using Calcium Cyanamide for Control of Senecio vulgaris in Leafy Vegetables

Abstract Weed management is a critical component of agricultural production, presenting significant challenges to farmers. The efficacy of traditional herbicides has been compromised due to increasingly stringent regulatory measures and the emergence of herbicide-resistant weed populations, complicating weed control efforts in conventional farming systems. Calcium cyanamide, a nitrogen-based fertilizer, has been identified for its phytotoxic properties, which may be leveraged for weed suppression. The necessity for effective weed control is particularly pronounced in some minor crops, where even minimal infestations of harmful weed species can jeopardize the entire yield, e.g. pyrrolizidine alkaloid containing plants in herbs. To assess the viability of calcium cyanamide as a weed management tool in leafy vegetable cultivation, a series of three experimental trials were conducted in Germany. In the initial trial, twenty different weed species were tested for their sensitivity to calcium cyanamide. Notably, Senecio vulgaris , an important weed known for its production of pyrrolizidine alkaloids that are toxic to mammals, exhibited a marked sensitivity to the treatment. This finding was corroborated in the subsequent trials, which also investigated the sensitivity of three leafy vegetable crops to calcium cyanamide. Lamb’s lettuce and arugula experienced yield reductions due to the application of calcium cyanamide, spinach demonstrated resilience and was unaffected by the treatment. As anticipated, the application of calcium cyanamide resulted in both nutritional and phytotoxic effects, which varied over time. The findings suggest that calcium cyanamide can serve as an effective component of integrated weed management strategies in leafy vegetable production, particularly for controlling S. vulgaris . However, it is imperative for growers to consider the degradation timeline of calcium cyanamide to mitigate the risk of phytotoxic damage to crops.