Brown rot caused by Monilinia laxa (Aderhold and Ruhland) Honey, M. fructicola (Winter) Honey (an EPPO A2 quarantine organism), or M. fructigena (Aderhold and Ruhland) is a serious fungal disease of peaches. Post-harvest losses are typically more severe than pre-harvest losses, and routinely occur during storage and transport, in some cases even affecting fruit at the processing stage. When the climatic conditions are unfavourable, Monilinia infections may remain latent until the conditions for disease development become favourable or the fruit matures when its susceptibility to disease increases. Latent infections have been described as an asymptomatic infection in which a host-parasite relationship has been established or as a dynamic equilibrium between the host, pathogen, and environment without any visible signs of disease. The incidence of latent infections ranges between 0 to 30% or even 50% of harvested fruit and most of this latent infections are produced the days preceding the harvest. However, most of the latent infections remain asymptomatic until fruit arrive to the markets, which is of especial importance in long distance exports.

Several molecular methods have been developed to identify and distinguish among Monilinia species on the visible presence of the fungus (van Brouwershaven et al. 2010). But none of these methods has been used to detect brown rot latent infections which detection consist on facilitating latent infection activation causing epidermis senescence either with paraquat, an herbicide, or by freezing the fruit at -20ºC for 48 hours (on-fit method) before 5-7 days of incubation to observe the pathogen.

The project focussed on the development and validation of molecular tests for the diagnosiss of Monilinia species in symptomatic and asymptomatic plant material.