Effect of non-aerated compost teas on damping-off pathogens of tomato

Compost teas are fermented watery extracts of composted materials that are used for their beneficial effects on plants including antimicrobial activities. Non-aerated compost teas (NCT) prepared from seaweed compost, shrimp powder compost, and chicken, bovine and sheep manure composts were tested for their effect on the in vitro growth of tomato root pathogens and for their effect on the development of damping-off diseases caused by Pythium ultimum and Rhizoctonia solani. Results showed that NCT prepared from the five types of compost had the ability to greatly reduce mycelial growth of P. ultimum, R. solani, Fusarium oxysporum f. sp. radicis-lycopersici and Verticillium dahliae in vitro. Sterilization of the NCT caused complete or partial loss of their inhibitory effect on mycelial growth of the pathogens. Application of NCT decreased the percentage of necrotic seedlings in P. ultimum-inoculated tomato seeds from 42% to 100%, but did not reduce necrosis in R. solani-inoculated seeds. When applied on tomato seedlings inoculated with damping-off pathogens, various NCT also increased seedling fresh and/or dry weights.