Trichoderma harzianum INAT11 elicits systemic resistance in maize against Fusarium verticillioides and Fusarium graminearum

Pink Ear Rot (PER) and Red Ear Rot (RER) are common fungal diseases of maize mainly caused by Fusarium verticillioides and Fusarium graminearum, respectively. Ear rots result in yield losses and reduced kernel quality due to contamination by mycotoxins. Since no chemical treatments are available to control Fusarium disease in maize, biological control could represent a promising sustainable strategy. A commercial strain of Trichoderma harzianum (INAT11) was evaluated as seed treatment to manage PER and RER through induction of a systemic resistance response in maize. Infection trials on maize plants under controlled greenhouse conditions showed the capacity of INAT11 when applied to seed to reduce both F. verticillioides and F. graminearum disease incidence (37% and 18.5%, respectively) and severity (33% and 28%, respectively). The expression of some genes belonging to both ISR (LOX10, AOS, HPL and OPR8) and SAR pathways (PAL and PR1), and also a stress-related gene (POX), were analysed in the hours following infection by quantitative real-time PCR. In treated plants during Fusarium infection some ISR and SAR markers were upregulated. The up-regulation occurred at different levels likely related to their pathogenic lifestyles

Effects of a prothioconazole- and tebuconazole-based fungicide on Aspergillus flavus development under laboratory and field conditions

Aspergillus flavus is a fungal pathogen of crops including maize and is frequently associated with the accumulation of aflatoxin, which presents a concern for human and animal health. In maize, good agricultural practices can only partially reduce Aspergillus occurrence, and biological control through atoxigenic strains decreases aflatoxin content, but increasing mold decreases kernel quality. The control of Aspergillus infections by chemicals is not authorized in maize, but recently in Italy, some sterol-biosynthesis inhibitors obtained an emergency authorization for use against Fusarium infections. Therefore, it could be interesting to determine if these inhibitors could also be useful against A. flavus. A mixture of prothioconazole and tebuconazole was tested in vitro on toxigenic and atoxigenic strains and on populations with respect to conidial germination, germinal potential and fungal growth. The fungicide mixture inhibited fungal growth, with a higher effect on toxigenic strains than on atoxigenic strains. All considered parameters were significantly reduced for monoconidial strains at doses lower than those recommended for field application for straw cereals; however, under-dosing should be avoided since it increases aflatoxin production. Field trials under natural infection conditions revealed the efficacy of the fungicide treatment on the reduction of both Aspergillus occurrence and aflatoxin accumulation in maize. In a context in which the sustainable use of pesticides can be guaranteed, our findings support the inclusion of azole-based fungicides in a multiple-strategy approach to control Aspergillus infections in maize