Harry A. J. Hoitink, Professor, Department of Plant Pathology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, Ohio; Carol A. Musselman and Terry L. Moore, Research Assistants, Department of Plant Pathology, Ohio Agricultural Research and Development Center, The Ohio State University; Leona E. Horst, Research Assistant; Charles R. Krause, Adjunct Associate Professor, U.S. Department of Agriculture, Agricultural Research Service, Application Technology Research Unit, Wooster, Ohio; Randy A. Zondag, Ohio State University Extension, Chair and Extension Agent, Lake County, Painesville, Ohio; and Hannah Mathers, Assistant Professor, The Ohio State University, Department of Horticulture and Crop Science, Columbus, Ohio.
Composted dairy and swine manures and municipal biosolids were tested as amendments in nursery container media to determine their effects on plant growth and health. These composts, when incorporated into nursery media at a volumetric amendment rate of 5 to 6 %, suppressed root rots and provided excellent growth on all but one of 40 plant species tested.
Viola, a low-fertility crop that did not respond well initially, recovered later in the season. One batch of composted manure naturally suppressed a foliar disease as well.
However, several other batches of composts, including several batches of composted dairy and swine manures and composted municipal biosolids tested in cooperating nurseries, did not suppress foliar diseases. Inoculation of these compost-amended media with Trichoderma hamatum 382, a biocontrol agent that induces systemic resistance to disease in plants, significantly reduced the severity of several different types of foliar diseases.
In conclusion, inoculation of compost-amended container media with T. hamatum 382 suppressed root as well as foliar diseases and supported excellent growth of nursery stock.