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United States Department of Agriculture

Agricultural Research Service

Title: Effect of Selected Pesticides on Dactylaria Higginsii, a Potential Bioherbicide for Purple Nutsedge

Authors
item Ables, Camilla
item Rosskopf, Erin
item Charudattan, Raghavan - UNIV. OF FLORIDA
item Pitelli, Robinson - UNIV. OF SAO PAULO

Submitted to: Weed Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 23, 2005
Publication Date: May 1, 2006
Citation: Ables, C.Y., Rosskopf, E.N., Charudattan, R., Pitelli, R. 2006. Effect of selected pesticides on dactylaria higginsii, a potential bioherbicide for purple nutsedge. Weed Technology. 20:255-260.

Interpretive Summary: The fungus Dactylaria higginsii is a promising biological control agent for purple nutsedge. Laboratory tests were performed in order to determine if this biological control agent can be used in conjunction with other pest control measures in tomato production. The effects of selected pesticides labeled for tomato were determined using mycelial growth on pesticide-amended culture medium and spore germination as indicators of pesticide sensitivity. Among all of the pesticides tested, oxyfluorfen and sethoxydim inhibited D. higginsii mycelial growth and conidial germination. Diuron, metalaxyl, thiophanate methyl, copper hydroxide, and cyromazine reduced mycelial growth but did not reduce conidial germination, while imazapyr had no adverse effect on either the mycelial growth or the conidial germination of D. higginsii. In general, long-term exposure of the fungus to the pesticides by growing it on culture media amended with pesticide resulted in reduced or inhibited mycelial growth while short-term exposure of conidia to the pesticides did not reduce or inhibit conidial germination. Some of the pesticides tested can be used to control other pests in a cropping system that also employs D. higginsii for the control of purple nutsedge.

Technical Abstract: The suitability of a bioherbicide as a component of an integrated weed management program not only relies on its field efficacy but also on its compatibility with other pest control measures that may be employed during the cropping season. The effects of selected pesticides, applied according to label rates, on the biological control agent Dactylaria higginsii were determined using mycelial growth on pesticide-amended potato dextrose agar (PDA) and conidial germination as indicators of pesticide sensitivity. Among all of the pesticides tested, oxyfluorfen and sethoxydim inhibited D. higginsii mycelial growth and conidial germination. Diuron, metalaxyl, thiophanate methyl, copper hydroxide, and cyromazine reduced mycelial growth but did not reduce conidial germination, while imazapyr had no adverse effect either the mycelial growth or the conidial germination of D. higginsii. In general, long-term exposure of the fungus to the pesticides by growing it on culture media amended with pesticide resulted in reduced or inhibited mycelial growth while short-term exposure of conidia to the pesticides did not reduce or inhibit conidial germination. These results indicate that some of the pesticides tested can be used to control other pests in a cropping system that also employs D. higginsii for the control of purple nutsedge.

Last Modified: 7/31/2014
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