Date of Award

Fall 2020

Project Type

Thesis

Program or Major

Natural Resources

Degree Name

Master of Science

First Advisor

Richard J Smith

Second Advisor

Serita Frey

Third Advisor

Anissa Poleatewich

Abstract

Soil fungi, by damaging or decaying weed seeds in the soil seed bank, are important agents of biological weed control. Pesticide seed treatments (PST) that include fungicides may alter the communities of soil fungi that colonize weed seeds in the soil and therefore the nature and efficacy of this important source of biological weed control. Tillage, by disrupting fungal networks and spatially redistributing the fungicides associated with PST throughout the soil profile, may mediate the effects of PST on seed coat fungi. We conducted a two-year experiment at two sites with two levels of PST (treated and untreated crop seeds) and three levels of tillage (Full, Strip, and No-Till) and analyzed the fungal community on Amaranthus retroflexsus seed coats. We found that at our no-till site, fungal communities were less diverse in the presence of PST. We also found simplification of seed coat fungal communities between tillage treatments. These results suggest that both PST and tillage may modify the weed control effects of soil fungal communities and these effects should be further studied and considered when employing these common management practices.

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