Author
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Bruck, Denny |
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Submitted to: Journal of Environmental Horticulture
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 4/1/2007 Publication Date: 9/1/2007 Citation: Bruck, D.J. 2007. Efficacy of Metarhizium anisopliae as a curative application for black vine weevil (Otiorhynchus sulcatus) infesting container-grown nursery crops. Journal of Environmental Horticulture. 25(3):150-156. Interpretive Summary: The black vine weevil (BVW), Otiorhynchus sulcatus (F.), is a serious pest of nursery crops. The insect killing fungus, Metarhizium anisopliae (F52), is registered by the US Environmental Protection Agency for BVW control. The objective of this study was to determine the efficacy of a fungal application to the surface of nursery containers infested with BVW larvae. Trials were performed in the spring of 2004 and 2005 as well as the fall of 2006. Laboratory studies were also performed to quantify the impact of temperature (10, 15, 20, 24 and 28 degress C) on fungal growth and speed of kill. Metarhizium anisopliae applied in the greenhouse and outdoors in 2004 were 92 and 30% effective, respectively. Fungal applications to container-grown plants maintained outdoors in the spring of 2005 were nearly 100% effective at eliminating larvae 28 days after application. Fall applications in 2006 provided statistically significant reductions in the number of live BVW larve per pot, but were not as effective as spring applications in 2005. Laboratory experiments demonstrated that temperatures below 20 degress C significantly slowed fungal growth and the speed at which M. anisopliae infected BVW larvae. With adequate soil temperatures, surface applications of M. anisopliae spores were very effective at eliminating BVW infestations in container-grown nursery plants. The use of M. anisopliae surface applications has limitations similar to the use of nematodes for BVW control in regard to soil temperature. Therefore, applications will have to be made as early in the fall as possible once egg laying has ended or potentially late in the spring just prior to pupation. Technical Abstract: The black vine weevil (BVW), Otiorhynchus sulcatus (F.), is a serious pest of nursery crops. The fungus, Metarhizium anisopliae (F52), is registered by the US Environmental Protection Agency for BVW control. The objective of this study was to determine the efficacy of a curative drench application of M. anisopliae for BVW larval control in container-grown nursery plants. Trials were performed in the spring of 2004 and 2005 as well as the fall of 2006. Laboratory studies were also performed to quantify the impact of temperature (10, 15, 20, 24 and 28 degrees C) on fungal growth and speed of kill. Metarhizium anisopliae applied in the greenhouse and outdoors in 2004 were 92 and 30% effective, respectively. Fungal applications to container-grown plants maintained outdoors in the spring of 2005 were nearly 100% effective at eliminating larvae 28 days after application. Fall applications in 2006 provided statistically significant reductions in the number of live BVW larve per pot, but were not as effective as spring applications in 2005. Laboratory experiments demonstrated that temperatures below 20 degrees C significantly retarded fungal growth and the speed at which M. anisopliae infected BVW larvae. When soil temperatures were adequate, topical drench applications of M. anisopliae were very effective at eliminating BVW infestations in container-grown nursery plants. The use of M. anisopliae curative drench applications has limitations similar to the use of nematodes for BVW control in regard to soil temperature. Therefore, applications will have to be made as early in the fall as possible once egg laying has ended or potentially late in the spring just prior to pupation. |