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 Powdery Mildew of Begonia with Composted Dairy Manure and T382
The protective effects of the compost were tested in a light fibrous Sphagnum peat mix that is used widely for greenhouse crops. Data in Table 1 show that the severity of powdery mildew on Begonia hiemalis 'Barbara' plants grown from rooted cuttings in a light fibrous H2 - H3 on the von Post peat decomposition scale Sphagnum peat mix (70% peat, 30% perlite, v/v) was controlled on plants sprayed with the fungicide Piperon.
| Table 1: Systemic Control of Powdery Mildew of Begonia (Begonia Hiemalis 'Barbara') Provided by a Composted Cow Manure-Amended Potting Mix and Trichoderma hamatum 382. | ||||
| Potting Mix1 | Control Treatment2 | Disease Severity3 (AUDPC) |
Dry Weight4 (gm) |
Salability5 |
| peat | control | 1,402.8 a | 4.6 c | 2.6 c |
| peat | Piperon | 363.2 bc | 7.1 ab | 3.7 b |
| peat | T382 | 100.3 c | 7.5 a | 4.4 a |
| SD compost | control | 347.3 bc | 5.7 bc | 3.9 ab |
| SD compost | Piperon | 216.8 bc | 7.6 a | 4.1 ab |
| SD compost | T382 | 521.4 b | 7.0 ab | 3.8 ab |
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1 Peat mix (Sphagnum peat, perlite; 7:3, vol./vol.). SD compost represents 5% of peat replaced with sawdust-bedded composted cow manure. 2 Piperon applied biweekly as a topical spray to the foliage; T382 was incorporated into the potting mix at 3 oz. of a granular preparation of T382 per cubic yard of mix. 3 Area under the disease progress curve based on mean disease severity ratings (n = 9); values followed by the same letters do not differ significantly based on Fisher's LSD test. 4 Mean dry wt. (g) per plant (n = 9) determined 55 days after potting. 5 Mean salability (n = 9) at flowering based on the following rating scale: 5 = healthy with 1 or more flower stalks with at least 1 flower open; 4 = with buds or flower stalks with minimal damage to leaves; 3 = no flowers or flowers with minimal damage; 2 = no flowers, small and/or damaged plants; 1= dead plant. |
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Furthermore, plant dry weights and the salability of plants also were significantly higher on plants sprayed with Piperon. Inoculation of the peat mix with the biocontrol agent T382 was at least as effective as the Piperon treatment. Amendment of the peat mix with 5% composted dairy manure also suppressed the disease. Both treatments increased plant dry weight and improved salability. Neither Piperon nor T382 added to the protective effect induced by this batch of composted dairy manure.
In conclusion, this specific batch of composted dairy manure naturally suppressed powdery mildew. This compost treatment and T382 were as effective as the fungicide Piperon. The effect is best explained on the basis of systemic-induced resistance. This effect is highly unusual because most composts do not induce this effect naturally.