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ARS Home » Pacific West Area » Corvallis, Oregon » Horticultural Crops Research Unit » Research » Publications at this Location » Publication #231973

Title: Impact of Fungicides on Metarhizium anisopliae in the Rhizosphere, Bulk Soil and In Vitro

Author
item Bruck, Denny

Submitted to: BioControl
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/18/2009
Publication Date: 8/1/2009
Citation: Bruck, D.J. 2009. Impact of fungicides on Metarhizium anisopliae in the rhizosphere, bulk soil and in vitro. Biocontrol. 54(4):597-606.

Interpretive Summary: The insect-killing fungus Metarhizium anisopliae (Metchnikoff) Sorokin (Hypocreales: Clavicipitaceae) is registered in the United States and the Netherlands for black vine weevil, Otiorhynchus sulcatus (Coleoptera: Curculionidae) control in container-grown ornamentals. These studies were conducted to determine the compatibility of M. anisopliae (F52) with a wide range of fungicides commonly applied to container-grown ornamentals for the management of soil-borne plant pathogens. The impact of fungicides on spore germination and fungal growth were determined in the laboratory. In addition, M. anisopliae persistence in bulk and rhizosphere soil was determined 30 days following dual application of each fungicide at 7-28 day intervals as prescribed. A number of fungicides (Cleary’s 3336, Stature DM, Captan, Terraguard, Banrot, Compass, Insignia, Heritage) inhibited spore germination in the laboratory relative to the untreated control. A larger number of fungicides (Alliette, Cleary’s 3336, Stature DM, Captan, Terraclor, Terraguard, Banrot, Medallion, Compass, Insignia, Hurricane, Iprodione Pro, Heritage, Agri-Fos) inhibited fungal growth in the laboratory relative to the untreated control. Only three fungicides (Terrazole, Banol and Subdue Maxx) had no significant impact on the fungus in the laboratory. While a number of fungicides had a detrimental impact in the laboratory, there was no impact on fungal populations in potting soil following two applications of any fungicide. However, there were fungicides that had a detrimental impact on fungal populations in the rhizosphere, particularly those with short reapplication intervals.

Technical Abstract: The entomopathogenic fungus Metarhizium anisopliae (Metchnikoff) Sorokin (Hypocreales: Clavicipitaceae) is registered in the United States and the Netherlands for black vine weevil, Otiorhynchus sulcatus (Coleoptera: Curculionidae) control in container-grown ornamentals. These studies were conducted to determine the compatibility of M. anisopliae (F52) with a wide range of fungicides commonly applied to container-grown ornamentals for the management of soil-borne plant pathogens. The impact of fungicides on spore germination and mycelial growth were determined in vitro. In addition, M. anisopliae persistence in bulk and rhizosphere soil was determined 30 days following dual application of each fungicide at 7-28 day intervals as prescribed. A number of fungicides (Cleary’s 3336, Stature DM, Captan, Terraguard, Banrot, Compass, Insignia, Heritage) inhibited spore germination in vitro relative to the untreated control. A larger number of fungicides (Alliette, Cleary’s 3336, Stature DM, Captan, Terraclor, Terraguard, Banrot, Medallion, Compass, Insignia, Hurricane, Iprodione Pro, Heritage, Agri-Fos) inhibited mycelial growth in vitro relative to the untreated control. Only three fungicides (Terrazole, Banol and Subdue Maxx) had no significant impact in vitro on spore germination or mycelial growth. While a number of fungicides had a detrimental impact in vitro, there was no impact on fungal populations in bulk soil following dual application of any fungicide. However, there were fungicides that had a detrimental impact on fungal populations in the rhizosphere, particularly those with short reapplication intervals. As researchers develop rhizosphere competence as an alternative management strategy for black vine weevil, the fungicides Captan and Terraguard should be avoided.