The development of environmentally friendly control methods to mitigate the severe damages caused by Phytophthora cinnamomi in the Mediterranean climate-type ecosystems is essential. In this way, crop waste and by-products which represent between 13 and 65% of agriculture production, are a rich source of bioactive compounds with antifungal and biocide activity. The main objective of this work was to determine the biocide activity against P. cinnamomi of three organic extracts. These extracts enriched in bioactive compounds come from residues of asparagus (Asp) and olive crops (Oliv and OH, from fruits and leaves respectively). They were evaluated at two doses (0.15 and 0.10%) on the mycelial growth and sporangial production of P. cinnamomi by in vitro experiments. Mycelial growth and sporangial production were significant reduced from the three plant extracts at the two doses tested, reaching a total inhibition with Asp at both doses. In general, no phytotoxicity symptoms were observed on seed germination and plant development, except for a plant yield reduction in the substrate treated with Oliv and Asp at the highest dose. In experiments performed in artificially infested soil, Asp induced a reduction of chlamydospores viability greater than 75% compared to unamended soil. Additionally, in planta experiments showed a significant reduction in plant mortality in substrate amended with OH. These results suggest that soil application of Asp and OH can limit P. cinnamomi infectivity and survival, setting the first steps to develop a sustainable method to control the root disease based on agricultural waste circular economy.

The aim of the study was to assess the impact of plant extracts from hemp inflorescences (H10-10% and H20-20%), as well as a mixture of extracts from hemp inflorescences, sage, and tansy leaves (M10-10% and M20-20%) on phytotoxicity and selected physiological and biometric parameters of wheat seedlings, as well as the biological activity of soil in a growth chamber experiment. In all experimental combinations, a low phytotoxicity of the extracts was observed in the form of leaf tip yellowing, classified as first-degree damage or its complete absence. The plant extracts and their mixtures, except for the H20 extract, had an inhibitory effect on the development of fungal pathogens, especially Fusarium spp. The H20 extract increased the fresh and dry weight of root seedlings. The tested extracts also had a positive effect on the chlorophyll content in seedlings. The highest chlorophyll concentrations were recorded for the seedlings sprayed with the M20 extract mixture. The applied plant extracts influenced the activity of soil enzymes. The highest activity of catalase and dehydrogenases was observed after spraying seedlings with M20, while the lowest was recorded after applying H10. Of all the tested groups of soil environment compounds included in the Biolog EcoPlates test, carbohydrates and carboxylic acids were most actively utilized. Conversely, amines and amides constituted the group of compounds utilized the least frequently. The present study demonstrated the high effectiveness of plant extracts on wheat seedlings due to their biocidal action against phytopathogenic fungi and increased biological activity of the soil. This research serves as an initial phase of work, which will aim to verify the results obtained under field conditions, as well as assess the biological stability of the extracts.