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.
Suppression of Botryosphaeria Stem Blight and Dieback on Myrica pensylvanica Induced by T382 in a Composted Biosolids-Amended Container Medium
Liners of Myrica pensylvanica (Northern Bayberry) were transplanted on March 20, 2002, in 1-gallon containers into a potting mix containing aged pine bark, light fibrous Sphagnum peat, composted biosolids, expanded shale, and sand at volumetric ratios of 9.0:1.5:0.75:1.0:0.33. The same mix, but inoculated with 7 oz. granular inoculum of T382 per cubic yard of mix, served as a second treatment.
Shortly after transplanting, a stem blight and dieback disease caused by Botryosphaeria dothidea developed. Progress of this stress disease declined in early May, and on May 16, final disease severity values were determined.
Data in Table 2 reveal that inoculation of the composted biosolids-amended mix with T382 significantly affected the severity of this stress disease. In the compost amended mix, 20.8% of the plants were killed, and only 25% of the plants were symptomless. Most were stunted in growth. Only 6.3% of the plants in the T382-inoculated mix were killed, and 66.7% of the plants were symptomless.
| Table 2. Suppression of Botryosphaeria Stem Blight and Dieback of Myrica pensylvanica by Trichoderma hamatum 382 (T382) in a Composted Biosolids-Amended Container Medium. | ||||
| Potting Mix1 | Mean Dieback Severity2 |
Mean % Plants Killed2 |
Mean % Symptomless Plants |
|
| control | 2.4 | 20.8 | 25.0 | |
| T382 | 1.5 | 6.3 | 66.7 | |
| LSD 0.05 | 0.4 | 14.1 | 20.4 | |
|
1 Liners potted on March 20, 2002, in 1-gallon pots in a container medium consisting of "aged" pine bark, sphagnum peat, composted biosolids, expanded shale, and sand (9:1.5:0.75:1:0.33; vol./vol.) (control) or inoculated with 7 oz. of T382 granular inoculum per cubic yard of mix (T382). 2 Mean dieback severity based on four blocks of 12 plants per treatment (n = 48) determined on May 16, 2002, using a scale in which 1 = symptomless, 2 = slight stunting, 3 = severe stunting, and 4 = dead plant. |
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In conclusion, this batch of natural composted biosolids-amended mix did not provide control of the foliar and stem disease. In contrast, inoculation of the mix with T382 provided effective control of Botryosphaeria dieback. The results of this demonstration trial are in line with controlled greenhouse studies which showed that composts generally do not provide systemic effects against plant diseases unless inoculated with biocontrol agents that can activate systemic resistance.