© 2005 Plant Management Network.
First Report of Association Between Delphinium and Peziza repanda
Stephen N. Wegulo, Assistant Specialist in Cooperative Extension, Miguel Vilchez, Staff Research Associate, and John Menge, Professor, University of California, Riverside 92521
Corresponding author: Stephen N. Wegulo. email@example.com
Wegulo, S. N., Vilchez, M., and Menge, J. 2005. First report of association between delphinium and Peziza repanda. Online. Plant Health Progress doi:10.1094/PHP-2005-0214-01-HN.
Delphinium (Delphinium spp.) is a popular field-grown cut flower. Most of the crop in the United States is grown in California, which accounts for more than 80% of U.S. sales (2). This report documents the first observation of an association between delphinium and an ascomycetous cup fungus. On 12 February 2004 during a visit to a delphinium field (Fig. 1) in southern California, the grower expressed concern about a fungal growth that was so abundant it was causing difficulty for workers walking through the field to harvest the crop. There were numerous fruiting bodies (apothecia) of the fungus at various growth stages. More than 80% of the fruiting bodies were associated with delphinium stems, emerging at the same point in the soil that the stems had emerged. Fruiting bodies were fleshy, brittle, single or clustered, lacking a stalk, and cup-shaped when young but spreading and becoming wavy and irregular to nearly flat when mature (Figs. 2 and 3). They measured 4 to 10 cm across. The upper (inner) surface was pale brown to medium brown; the exterior surface was pale. Based on fruiting body morphology and spore characteristics, the fungus was identified as Peziza repanda (1).
Two fields were infested. They were separated by a distance of approximately 30 m and planted with Delphinium × belladonna and D. × belladonna ‘Bellamosum.’ Seedlings were transplanted into these fields in October 2003 and P. repanda was observed in association with stems in one of the fields when plants were approximately 15 cm tall. In the infested part of this field, incidence of association of the fungus with plants was 17% on 13 February 2004. Because the fungus was rogued when plants were young, this incidence is lower than it would have been if there had been no roguing. In the other field, approximately 50% of plants in the infested part of the field were associated with the fungus on 12 February 2004. Presence of P. repanda in this field was noticed in mid-January 2004 during harvesting. At that time many of the fruiting bodies were mature and abundant.
Although in the majority of associations the fungus did not appear to do any harm to the plants, in approximately 1% of associations it appeared to retard plant growth and in a few cases it caused plant death (Fig. 3). This may have been due to competition for space, water, and nutrients. The major concerns the grower had were unsightliness of the fungus in the fields and the difficultly it caused for workers to walk through the fields. Because P. repanda was concentrated only in certain parts of each of the fields, we suspect that plug trays were contaminated with its spores. This fungus is common in nurseries that raise plugs on container media amended with wood material. Nursery growers should be aware of the potential for contamination of these media with spores of fungi commonly associated with wood.
1. Arora, D. 1986. Mushrooms Demystified: A Comprehensive Guide to the Fleshy Fungi. 2nd ed. Ten Speed Press, Berkely, CA.
2. USDA National Agricultural Statistics Service. 2002. Floriculture crops: 2001 summary. Agricultural Statistics Board. Sp Cr 6-1 (02)a.