Field evaluation of biological control agents and calcium-based fertilizers to control plasmodiophora brassicae in broccoli (Brassica oleracea var. italica)

Broccoli plants are frequently attacked by the biotrophic pathogen Plasmodiophora brassicae, which leads to continuous significant economic losses during its cultivation. Finding environmentally friendly methods to control this aggressive pathogen is a priority. Here, broccoli plants were sown in a field that has been previously reported with a high incidence of the pathogen showing dramatic root damage and yield loss. Field evaluations were performed to evaluate lump weight, root weight, and lump diameter after soil application with Trichoderma spp., Bacillus sp., humic acids, commercial plant defense elicitor, calcium carbonate (CaCO3), and calcium nitrate (Ca(NO3)2). Treatments were applied individually and in combination during two continuous and independent production seasons (rainy and dry seasons) in the year 2018.In summary, the application of CaCO3 increased the lump weight by 25% respective to its control, but only during the dry season. Moreover, the best treatment giving a consistent increase in lump weight (20% to 50% compared to its non-treated control depending on the season) was the combination of all treatments (biological and calcium-based fertilizers) when tested during both seasons. Taking all together, it was found some alternatives that increased the production of broccoli in fields infested with Plasmodiophora brassicae. These alternatives will be validated in the future in different soil types and agricultural environments.