Evaluation of the Potential of Agro-Industrial Waste-Based Composts to Control Botrytis Gray Mold and Soilborne Fungal Diseases in Lettuce

Abstract

Composts are widely used in horticulture as organic amendments to improve the properties of soils. Composts have also been reported to enhance the disease suppressive potential of soils and, therefore, could be used as a strategy for managing plant diseases. The aim of this study was to test the ability of soils amended with four different agro-industrial waste-based composts (chestnut peels and shells, spent coffee grounds, grape marc, and olive leaves) to inhibit the growth and activity of Botrytis cinerea and several soilborne pathogens. First, the capacity of aqueous compost extracts to inhibit the growth of Botrytis cinerea and five soilborne fungi was evaluated in vitro using a broth macrodilution method. Second, lettuce plants were grown on soils amended with composts and inoculated either with B. cinerea or the soilborne fungus Fusarium oxysporum Schlechtendahl isolated from lamb’s lettuce. The determination of minimal inhibitory concentrations indicated that none of the composts inhibited the mycelium growth of the selected fungal pathogens. However, the pathogens did not cause any damage on plants grown on the chestnut- and olive-based composts. Lettuce yields were also highest for plants grown with composts made from chestnut and olive, irrespective of the amount of compost incorporated into soils (5% or 10%, weight basis). The grape-based compost also exhibited a fertilization effect, although the effect was associated with increased Fusarium wilt severity. Both N immobilization and symbiosis with the compost’s microflora were used to explain the pathogenicity of F. oxysporum Schlechtendahl in response to amendment with composts made from grape and coffee wastes. The beneficial effects of the chestnut- and olive-based composts reported in this study could be exploited in strategies aimed at reducing reliance on synthetic pesticides for the control of fungi in lettuce cultivation.

Spectroscopic and Physicochemical Characterization of Poultry Waste-Based Composts and Charcoal–Compost Mixtures for the Prediction of Dry Matter Yield of Giant of Italy Parsley

“…Further research is needed to identify the mechanism of action of charcoal as well as the most critical factors influencing EC that may be managed to obtain a good estimate of the amount of charcoal to add to each organic amendments to achieve maximum crop productivity. If well managed, charcoal waste from the poultry industry might well become an alternative to substrates such as peat [10].…”

“…Maximum crop productivity is dependent not only on the C:N ratio of the composts, but on other nutritional quality parameters as well, which enable growing substrates to act as a nutrient reservoir, thus contributing to successful seedling establishment and vigorous plant growth [9]. This is particularly important for pot-grown plants, as in this case, the growing substrates must sustain plants throughout their entire life cycle [10]. Organic amendments produced from agro-industrial wastes are well known to be rich in nutrients and to play vital roles in plant development [11][12][13][14].…”