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ARS Home » Midwest Area » Ames, Iowa » Corn Insects and Crop Genetics Research » Research » Publications at this Location » Publication #128783
Title: FUNGICIDAL EFFECTS OF GLYPHOSATE AND GLYPHOSATE FORMULATIONS ON FOUR SPECIES OF ENTOMOPATHOGENIC FUNGI

Author
item MORJAN, WILMAR - IOWA STATE UNIVERSITY
item PEDIGO, LARRY - IOWA STATE UNIVERSITY
item LEWIS, LESLIE

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/30/2002
Publication Date: N/A
Citation: N/A

Interpretive Summary: There are several naturally occurring fungi that cause disease in insect pests. These fungi can be found in the soil, on crop residue, and of course in insects killed by the fungi. In certain crops such as soybean and corn, these fungi help in keeping populations of insects and mites below an economic level. Some herbicides are known to kill fungi. With the event of RoundUp Ready [glyphosate (N-phosphonomethyl]glycine)] soybea and corn, some herbicides will be used after the crop is emerged, thus maybe exposing insect-killing fungi to these chemicals. Research was conducted to determine if glyphosate (active ingredient in RoundUp) and the inert ingredients in RoundUp formulations are harmful to these fungi. Glyphosate alone had no effect on Metarhizium anisopliae, Beauveria bassiana, Nomuraea rileyi, and Neozygites floridana; however, these fungi were inhibited in growth by the formulations used to dispense the active ingredient glyphosate. Field responses of these fungi to herbicides shoul be determined to assure that these natural control agents are not harmed. This research will assist entomologists in developing integrated pest management programs for row crops.

Technical Abstract: Fungicidal effects of glyphosate and glyphosate formulations on the entomopathogenic fungi Beauveria bassiana (Balsamo) Vuillemin, Metarhizium anisopliae (Metchnikoff) Sorokin, Nomuraea rileyi (Farlow) Samson, and Neozygites floridana Weiser and Muma were evaluated under laboratory conditions. Media previously inoculated with entomopathogenic fungi were exposed to distilled water, glyphosate (active ingredient), seven glyphosate formulations, and five blank formulations (carrier only). The fungicidal activity was determined by measuring inhibition in mycelial growth in solid media (B. bassiana, M. anisopliae, and N. rileyi), and spore density in liquid medium (N. floridana). Glyphosate did not have fungicidal activity against any of the fungi tested. Fungicidal properties of glyphosate formulations varied among fungal species. Neozygites floridana and M. anisopliae were susceptible to all glyphosate formulations. RoundUp [glyphosate (N-[phosphonomethyl]glycine)] Ready-To-Use was consistently the glyphosate formulation with one of the strongest fungicidal properties. Fungicidal activity of some formulations had a synergistic effect with glyphosate. RoundUp Original was the only formulation that did not show any interaction on fungicidal activity between glyphosate and the formulation. The results showed that the four fungi tested are susceptible to various glyphosate formulations when exposed to field concentrations.