Trichoderma harzianum seed treatment controls Fusarium verticillioides colonization and fumonisin contamination in maize under field conditions

• Trichoderma harzianum maize seed treatment was studied in 3 years field trials in 2 sites.
• Treatment with T. harzianum reduces infection of both roots and silk by Fusarium verticillioides.
• Maize kernels coming from treated seeds have less F. verticillioides and fumonisins.
• Involvement of systemic resistance against F. verticillioides appears conceivable.
• T. harzianum colonizes roots and remains there at least until the flowering stage.

In northern Italy, the most frequently occurring class of mycotoxins in maize are fumonisins, mainly those produced by Fusarium verticillioides. Currently, good agricultural practices (GAPs) represent the best line of defense for controlling the contamination of maize by Fusarium-toxins. Annual fluctuations in weather conditions can strongly reduce the advantages conferred by GAPs, and thus integration with biological control strategies can be a sustainable way to achieve reliable control of Fusarium colonization and toxin contamination. Trichoderma harzianum is a good biocontrol agent against a wide range of plant pathogens, and previous studies have reported its ability to reduce F. verticillioides colonization under greenhouse conditions. Field trials were conducted in two locations to assess the effect of seed treatment with T. harzianum strain T22 on F. verticillioides kernel colonization and on fumonisin contamination under various natural conditions. An average reduction of 58% in fungal infestation and 53% in mycotoxin contamination was observed during our three-year experiments. This research suggests that seed biopriming with T. harzianum T22 can be a promising and environmentally friendly way to control F. verticillioides kernel colonization and fumonisin accumulation.