Efficacy of microbial consortia and natural compounds as seed treatment for tomato pathogen management

In this study the efficacy of experimental treatments based on microbial consortia (MC) (beneficial rhizobacteria and fungi, actinomycetes, arbuscular mycorrhizal fungi) and natural compounds (NCs) (chitosan and glucosinolates) as seed treatments for tomato bacterial and fungal pathogens management (Xanthomonas euvesicatoria pv. perforans, Xep; Pseudomonas syringae pv. tomato, Psto; Fusarium oxysporum f. sp. radicis-lycopersici, FORL) was evaluated. Independent trials were performed by using organic tomato seeds ‘San Marzano nano’. Treatments were performed by soaking seeds either in aqueous MC suspensions or NC dilutions. The direct effect on the seed inoculum was performed on seeds inoculated before the treatment either with Xep or FORL. All treatments induced a significant reduction of lesions caused by Xep whereas only one MC and both NCs were effective against FORL. A seed biopriming approach was investigated to protect plantlets against tomato pathogenic bacteria. Two-month-old tomato plantlets obtained from treated seeds were spray inoculated with bacterial suspensions of either Xep or Psto. Results showed a significant reduction of bacterial disease incidence and severity with some of the treatments with MC and NCs, although they varied according to the pathogen.