Mathilde Montibus

Fusarium graminearum is a fungal pathogen that can colonize small-grain cereals and maize and secrete type B trichothecene (TCTB) mycotoxins. The development of environmental-friendly strategies guaranteeing the safety of food and feed is a key challenge facing agriculture today. One of these strategies lies on the promising capacity of products issued from natural sources to counteract crop pests. In this work, the in vitro efficiency of sixteen extracts obtained from eight natural sources using subcritical water extraction at two temperatures was assessed against fungal growth and TCTB production by F. graminearum. Maritime pine sawdust extract was shown to be extremely efficient, leading to a significant inhibition of up to 89% of the fungal growth and up to 65% reduction of the mycotoxin production by F. graminearum. Liquid chromatography/mass spectrometry analysis of this active extract revealed the presence of three families of phenolics with a predominance of methylated compounds and suggested that the abundance of methylated structures, and therefore of hydrophobic compounds, could be a primary factor underpinning the activity of the maritime pine sawdust extract. Altogether, our data support that wood/forest by-products could be promising sources of bioactive compounds for controlling F. graminearum and its production of mycotoxins.

Four coating systems were exposed for one year outdoors at 45° south. They consisted of solventborne (alkyd based) and waterborne (acrylic based) systems in both clear and pigmented versions. Fungal growth visually assessed was compared to fungal enumeration, and the influence of exposure time on the main fungal species was studied. Results clearly showed that fungal growth was lower on the pigmented coating systems compared with their pigment-free versions. Although the clear solventborne coating included a higher amount of biocide, it was more susceptible to blue stain than the pigmented version. A new multifaceted exposure rig (MFER) also contributed to the study of fungal growth. It allowed samples to be exposed with nine different exposure directions and angles. Exposure using this MFER has shown that the worst cases (highest area and intensity of blue stain fungi) were for samples with the clear coating system exposed to north 45° and at the top of the MFER (horizontal surfaces). For any cardinal direction, all surfaces inclined at 45° displayed more blue stain fungi than vertical surfaces, due to a higher moisture content of the panels. Depending on the cardinal direction and the orientation, some surfaces were free of visible cracking, but colonized by fungi. It was concluded that the growth of blue stain fungi was not linked with cracking development.