• fusarium head blight
• biocontrol
• analisi statistica
• real time PCR
• prova in campo
• trichoderma gamsii

Fusarium Head Blight (FHB), also called scab, is a destructive disease worldwide affecting wheat and other cereals caused by a complex of fungal pathogens, mostly belonging to Fusarium genus. The importance of FHB is not only due to the significant yield reduction but also for the risk associated with mycotoxin contamination. During the disease cycle, crop debris and spikes at anthesis are recognized as critical points. Cultural debris are used by the pathogens to overwinter during the interval between two consecutive cropping seasons, and flowering is the most susceptible growth stage of wheat to infection. Different strategies are used to reduce the impact of FHB, including healthy seeds, crop rotation, tillage practices, fungicide application and planting resistant cultivars, but none is able to completely control this disease. In this scenario, biological control by the use of beneficial organisms, such as fungi, offers an additional eco-friendly tool that can also be used as part of an integrated management strategy.
Within the genus Trichoderma, many isolates are able to reduce pathogens growth by different mechanisms such as competition for space and nutrients. T. gamsii T6085, isolated from an uncultivated soil in Ukraine, is under investigation for many years at the Plant Pathology & Mycology Lab of the University of Pisa, where the present thesis has been done. This isolate is able to reduce the growth of F. graminearum and F. culmorum (two among the most important FHB causal agents) against which it can also show a mycoparasitic activity and, more important, it is able to reduce mycotoxin production.
Aim of the present work was to investigate the ability of T. gamsii T6085 to act as biocontrol agent against FHB on wheat in field. During this last cropping season, an experiment was performed at Centro Avanzi (University of Pisa) where wheat was cultivated under a sod-tillage field condition. T. gamsii T6085 was applied on soil at the beginning of stem extension to allow colonization of wheat straw in order to reduce, by competition for cultural debris, FHB causal agents’ inoculum and/or on spikes at anthesis, to reduce Fusaria infection of flowers.
Just before applying the antagonist in field, some experiments have been performed at lab-scale in order to define those conditions to obtain an enough amount of fungal biomass to be applied both on soil and on spikes. In order to put the antagonist in a competitive advantage with FHB causal agents, two poisoning compounds, sodium propionate and gallic acid, were evaluated on growth of T6085 and of F. graminearum, F. culmorum and F. langsethiae, all considered the most common causal agents of FHB. No one of these compounds seemed to affect pathogens’ growth so they were not used. The effects of two different herbicides (Floramix and Glifosate-Glyfos Dakar), used in field against weeds, were tested on T. gamsii T6085 resulting in any effect on the antagonist’s growth. Finally, millet was selected as fermenting substrate to produce T6085 biomass to be applied on soil in the field, whereas a spore suspension in water was used for spike inoculation at anthesis.
After T6085 was applied in field, wheat straw was sampled and used to quantify by Real-Time PCR the amount of the antagonist on cultural debris, allowing us to evaluate differences among thesis. The effect of T6085 application on spikes was evaluated by sampling spikes at regular time and it was expressed as disease index and disease severity, that resulted to be significantly lower in treated plots after one week from spikes inoculation.
This is the first time T6085 was tested under field condition on sod-seeded wheat. Preliminary results here reported confirmed the possibility to move from a lab- to a field-scale, but additional investigations are required in order to improve (qualitatively and quantitatively) biomass production and to evaluate different period of application and formulation for soil treatment and spore suspension formulation for spikes treatment.