Ornamental Plants
Annual Reports and Research Reviews 2002

Special Circular 189

Biological Suppression of Foliar Diseases of Ornamental Plants with Composted Manures, Biosolids, and Trichoderma hamatum 382

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.

Results and Discussion

Preliminary Data on Growth in Composted Swine-Manure-Amended Media

Composted hog manure was amended into a container medium on May 17, 2002. Media used at this nursery included:

1. The grower's mix consisting of aged pine bark, composted rice hulls, Sphagnum peat, and pea gravel (41:25:13.7:12.3; v/v).
2. The same mix but amended with 5% composted swine manure.
3. This hog manure compost-amended mix inoculated with 3 oz. of granular inoculum of T382 per cubic yard of mix.

Eighteen different woody ornamentals, including cultivars highly susceptible to foliar diseases (e.g., bacterial leaf spots and blights, Phytophthora dieback diseases), were planted in each of the three mixes.

A randomized complete block design was used for each treatment utilizing four blocks of 12 2-gallon containerized plants per treatment.

The severity of foliar diseases was monitored throughout the summer. Fungicide drenches were not applied to the crops. Foliar diseases did not develop on any of the crops due to extremely dry weather conditions. In late September 2002, the severity of root rot and the canopy size were determined for each treatment.

Mean root rot severity and the mean canopy size values for each crop did not differ significantly among treatments. In conclusion, composted hog manure served as an effective alternative amendment in the container medium used at this nursery. Neither beneficial nor detrimental effects were observed. T382 did not provide a response, probably due to the extremely low disease pressures that prevailed during the dry summer of 2002 at this location.