Mycotoxigenic fungi contaminating greenhouse-grown tomato fruit and their alternative control

Abstract

Tomato fruit represent a valuable but perishable commodity due to postharvest fungal spoilage. In the present investigation, greenhouse-grown tomatoes were analysed, particularly for the contamination by mycotoxigenic fungi. Collected isolates were characterized by morphological features and sequencing of barcoding genes. Alternaria, Aspergillus, and Penicillium proved to be the most represented genera. Particularly, Alternaria strains were mostly A. alternata morphotype alternata, genetically able to produce alternariol and alternariol monomethyl ether. Aspergillus strains were divided into yellow and black aspergilli; the former included the species A. westerdijkiae, A. ochraceus, and A. occultus, able to produce ochratoxin A (OTA), the latter included an A. welwitschiae strain, genetically able to produce OTA and fumonisins. Most Penicillium strains were represented by P. olsonii, not able to produce regulated mycotoxins. Commercial Generally Recognized As Safe (GRAS) and biostimulant formulations were tested for controlling those pathogens and related decays. Potassium bicarbonate and the combination peracetic acid+hydrogen peroxide proved to completely prevent fungal growth. The same formulations were tested on tomato fruit against A. alternata morphotype alternata, which proved to be the most aggressive pathogen. Tests confirmed potassium bicarbonate and the combination peracetic acid+hydrogen peroxide as effective against disease incidence and severity, particularly when applied by dipping. These promising results support their use in larger-scale trials.