Abstracts of New Publications from US Government Scientists on Biological Eradication of Opium Poppy
See http://www.apsnet.org/phyto/current/top.asp for information on the journal Phytopathology.
Publication no. P-2000-0530-02R
Biological ControlNep1 Protein from Fusarium oxysporum Enhances Biological Control of Opium Poppy by Pleospora papaveracea.
Bryan A. Bailey, Patricia C. Apel-Birkhold, Olutayo O. Akingbe, Jessica L. Ryan, Nichole R. O'Neill, and James D. Anderson. First, second, third, and fourth authors: Biocontrol of Plant Diseases Laboratory; fifth author: Soybean and Alfalfa Research Laboratory; and sixth author: Weed Science Laboratory, U.S. Department of Agriculture, Agricultural Research Service, Beltsville, MD 20705.
Phytopathology 90:812-818.
Accepted for publication 28 April 2000.This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 2000.
The fungus Pleospora papaveracea and Nep1, a phytotoxic protein from Fusarium oxysporum, were evaluated for their biocontrol potential on opium poppy (Papaver somniferum). Four treatments consisting of a control, P. papaveracea conidia, Nep1 (5 µg/ml), and P. papaveracea conidia plus Nep1 (5 µg/ml) were used in detached-leaf and whole-plant studies. Conidia of P. papaveracea remained viable for 38 days when stored at 20 or 4¡C. Nep1 was stable in the presence of conidia for 38 days when stored at 4¡C or for 28 days at 20¡C. The presence of Nep1 did not affect conidia germination or appressoria formation. Nep1 was recovered from drops applied to opium poppy leaves in greenhouse and field studies 24 h after treatment. Opium poppy treated with the combination of Nep1 and P. papaveracea had higher necrosis ratings than the other treatments. There were changes in the intercellular protein profiles, determined by sodium dodecyl sulfate gel electrophoresis and silver staining, due to application of treatments; the most intense occurred in response to the combination of Nep1 and P. papaveracea. The combination of Nep1 and P. papaveracea enhanced the damage caused to opium poppy
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Publication no. P-2000-0421-01R
Biological Control
Dendryphion penicillatum and Pleospora papaveracea, Destructive Seedborne Pathogens and Potential Mycoherbicides for Papaver somniferum.
Nichole R. O’Neill, James C. Jennings, Bryan A. Bailey, and David F. Farr. First author: Soybean and Alfalfa Research Laboratory; second author: Weed Science Laboratory; third author: Biocontrol of Plant Diseases Laboratory; and fourth author: Systematic Mycology and Botany Laboratory, USDA, ARS, Beltsville, MD 20705.
Phytopathology 90:691-698.
Accepted for publication 25 February 2000.This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 2000.
Dendryphion penicillatum and Pleospora papaveracea were isolated from blighted Papaver somniferum and Papaver bracteatum plants grown in growth chambers and the field in Beltsville, MD. The etiology of the diseases was determined, and the fungi are being investigated as potential mycoherbicides to control the narcotic opium poppy plant. P. papaveracea is known to be a highly destructive seedborne pathogen of Papaver somniferum, causing seedling blight, leaf blight, crown rot, and capsule rot. Single conidia and ascospores were isolated and cultures established from naturally infested seed and diseased foliage and pods of opium poppy from Iran, Colombia, Venezuela, Sweden, India, and the United States (Maryland and Washington). Mycelia and conidia of P. papaveracea and D. penicillatum produced on necrotic leaf tissues appear morphologically similar, and the fungi were previously considered to be anamorph and teleomorph. However, no anamorph/teleomorph connection could be established, and the fungi appear to be distinct taxa. P. papaveracea produced conidia, mature pseudothecia, and chlamydospores in vitro and on infected stems. D. penicillatum produced conidia, microsclerotia, and macronematous conidiophores. Although both fungi were pathogenic to three poppy cultivars, conidial inoculum from P. papaveracea cultures was more virulent than conidial inoculum from D. penicillatum. Eight-week-old plants became necrotic and died 8 days after inoculation with a conidial suspension of P. papaveracea at 2 ¥ 10(^5) spores per ml. Disease severity was significantly enhanced by inoculum formulations that contained corn oil, by higher conidial inoculum concentrations, and by increased wetness periods. Symptoms on plants inoculated with either pathogen included leaf and stem necrosis, stem girdling, stunting, necrotic leaf spots, and foliar and pod blight. Inoculated seedlings exhibited wire stem, damping-off, and root rot. Conidia, and less frequently pseudothecia, of P. papaveracea and conidia of D. penicillatum were produced abundantly on inoculated, necrotic foliage, pods, and seedlings. Cultures from conidia or ascospores reisolated from these tissues consistently produced fungi whose morphologies were typical of the fungus from which the inoculum was derived.
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Publication no. P-2000-0503-01R
Biological Control
Evaluation of Infection Processes and Resulting Disease Caused by Dendryphion penicillatum and Pleospora papaveracea on Papaver somniferum.
Bryan A. Bailey, Patricia C. Apel-Birkhold, Nichole R. O’Neill, James Plaskowitz, Sharon Alavi, James C. Jennings, and James D. Anderson. First, second, and fifth authors: Biocontrol of Plant Diseases Laboratory; third author: Soybean and Alfalfa Research Laboratory; fourth author: Systematic Botany and Mycology Laboratory; and sixth and seventh authors: Weed Science Laboratory, ARS/USDA, Beltsville, MD 20705.
Phytopathology 90:699-709.
Accepted for publication 22 February 2000.This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 2000
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Two pathogenic fungi of opium poppy, Pleospora papaveracea and Dendryphion penicillatum, were isolated from field material in Beltsville, MD. The processes of infection by these two fungi were studied to determine the optimal environmental conditions for infection. Both fungi formed appressoria capable of penetrating directly through the plant epidermal layer. Of the two fungi, P. papaveracea was more aggressive, causing more rapid necrosis. Appressorial formation by P. papaveracea occurred as early as 4 h after application of a conidial suspension to poppy leaves. P. papaveracea formed more appressoria than did D. penicillatum, especially at cool temperatures (7 to 13°C). In greenhouse studies, P. papaveracea caused more damage to opium poppy than did D. penicillatum when applied in 10% unrefined corn oil. In the field, P. papaveracea was more consistent in its effects on opium poppy from a local seed source designated Indian Grocery. P. papaveracea caused higher disease ratings, more stem lesions, and equal or greater yield losses than did D. penicillatum on Indian Grocery. The late-maturing opium poppy variety White Cloud was severely damaged by disease, regardless of formulation or fungal treatment. P. papaveracea was the predominant fungus isolated from poppy seed capsules and the only fungus reisolated from the field the following year. These studies provide a better understanding of the infection process and the differences between these two pathogenic fungi and will be beneficial for the development of the fungi as biological control agents. Additional keywords: conidia, dew period, hyphae, mycoherbicide, pseudothecia, weeds.