Dimethomorph: an interdisciplinary approach through different plants and animal pathogenic oomycetes

Dimethomorph: an interdisciplinary approach through different plants and animal pathogenic oomycetes I.M.Nanni, P.Tedesco, R.Galuppi and M. Collina aDepartment of Agricultural and Food Science, University of Bologna, Viale G. Fanin 42, 40127 Bologna, Italy bDepartment of Veterinary Medical Sciences, University of Bologna, Via Tolara di Sopra 50, Ozzano dell'Emilia 40064 Bologna, Italy The class Oomycota gathers species that are pathogenic to plants and animals, including humans, these pathogens are able to cause economic losses in agriculture and aquaculture industry worldwide. Phytophthora infestans causes losses in potato and tomato crops for more than 6 billion per year, Plasmopara viticola is the causal agent of downy mildew, which is one of the most damaging grapevine disease. The genus Pythium, includes species that are pathogenic for both plants and animals, particularly, Pythium insidiosum was reported to cause disease in humans and in other mammals. Oomycetes of the order Saprolegniales are widely distributed in freshwater environments, causing infections in different taxa of aquatic animals. Among these members of the genus, Saprolegnia represent a severe problem in fish farms. Despite the wide distribution and the impact of the diseases caused by oomycetes on animal health and on economic activities, there are no effective available molecules against these pathogens. Dimethomorph was introduced in 1988 as a novel fungicide with high activity against oomycetes plant pathogens and authorized in Italy in 1994. Dimethomorph is still largely used to control downy mildew in Italy. In order to test the sensitivity of dimethomorph to P.viticola populations, a multi-year monitoring was carried out, showing a good efficacy in the control of the pathogen. Since there are limited possibilities to control oomycete infections in aquaculture, this fungicide was applied in in vitro assays on different species of Saprolegnia and Pythium. Preliminary in vitro results showed a non complete inhibition, but a significant slowdown in the mycelial growth. Additional microscopic studies are still ongoing to investigate how the molecule interferes with the mycelium of P. viticola and Saprolegnia. These findings would allow to further investigate the biology of different species of oomycetes, thus promoting the research across interdisciplinary scientific disciplines.