Testing the effectiveness of microbial biostimulants to increase the resistance of the variety Chardonnay to “Bois noir” phytoplasma

Abstract Bois noir (BN) of the grapevine is one of the phytoplasma diseases that have become increasingly prevalent in Czech vineyards in recent years, and causes economically significant damage. As no curative measures are currently known, indirect control methods are being sought to help reduce the negative impact on the vine and extend the life of the vineyard. In a trial with the variety Chardonnay, the following biostimulants were tested: NovaFerm ® SIRIUS (5.0 l/ha), NovaFerm ® ORION (5.0 l/ha) and Microfertile Carbon (5.0 l/ha), in the periods 2023 and 2024. When comparing plants with BN symptoms, the lowest number of plants with BN symptoms was found in the NovaFerm Orion variant. The NovaFerm Orion belongs to microbial biostimulants and shows a significant biostimulatory effect on growth, as there was a decrease in weakly growing plants during the growing season. When evaluating the effect on plant recovery, the biostimulant Microfertile Carbon showed the most significant effect, leading to a year-on-year recovery in the number of symptomatic plants.