Effectiveness of municipal waste compost and its humic fraction in suppressing Pythium ultimum.
The effect of addition of a municipal solid waste (MSW) compost and its water-soluble and humic fraction to suppress the effect of Pythium ultimum on pea plants was studied and compared with that of a chemical pesticide (metalaxyl). The biotic and abiotic characteristics of compost involved in the biocontrol effects of these materials were also evaluated. The addition into soil of whole composts and their humic fractions reduced the effect of the pathogen on pea plants, significantly reducing the number of root lesions and Pythium populations and avoiding reductions of plant growth. The greatest pathogen suppression was achieved with the chemical pesticide. However, it also caused a significant decrease in the number of nontarget bacteria and fungi and on beneficial soil microorganisms such as Trichoderma and Pseudomonas. Addition of organic amendments increased population size of nontarget and specific biocontrol microorganisms. The humic fraction showed similar results to compost. All this suggests that metalaxyl has a nonspecific effect, producing adverse effects on aspects of soil quality. This was avoided if the chemical pesticide was reduced and replaced by organic amendments such as an MSW compost or its humic fraction.
Department of Soil and Water Conservation and Organic Waste Management, Centro de Edafología y Biología Aplicada del Segura, CEBAS-CSIC, P.O. Box 4195, 30080 Murcia, Spain. jpascual@cebas.csis.es
J A
JA
Pascual
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C
Garcia
T
T
Hernandez
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Lerma
J M
JM
Lynch
D000383:Agriculture / Q000379:methods; D000409:Alanine / Q000031:analogs & derivatives* / Q000494:pharmacology; D018525:Germination / Q000187:drug effects; D006812:Humic Substances / Q000032:analysis / Q000494:pharmacology*; D018532:Pisum sativum / Q000382:microbiology / Q000469:parasitology*; D010571:Pest Control / Q000379:methods*; D010575:Pesticides / Q000494:pharmacology; D010935:Plant Diseases / Q000382:microbiology / Q000469:parasitology; D018517:Plant Roots / Q000382:microbiology / Q000469:parasitology; D018514:Plant Structures / Q000382:microbiology / Q000469:parasitology; D011775:Pythium / Q000187:drug effects* / Q000254:growth & development*; D012037:Refuse Disposal; D012639:Seeds / Q000187:drug effects / Q000254:growth & development; D012988:Soil Microbiology; D013242:Sterilization; D013997:Time Factors
D006812:Humic Substances; D010575:Pesticides; C028175:metalaxyl; D000409:Alanine