Date Approved

8-2018

Graduate Degree Type

Thesis

Degree Name

Biology (M.S.)

Degree Program

Biology

First Advisor

James McNair

Second Advisor

Charlyn Partridge

Third Advisor

Timothy Evans

Fourth Advisor

Daniel Frobish

Academic Year

2017/2018

Abstract

Gypsophila paniculata is an invasive species in Michigan’s northern lower peninsula and a problem invasive in much of the northern United States and Canada. Gypsophila paniculata readily outcompetes native plants in sandy, well-drained soils due to its deep taproot, which allows access to scarce resources. It reproduces and disperses mainly by seed, but the phenology of seed maturation is poorly understood. Gypsophila paniculata is of particular concern in lakeshore dunes because the areas where it is most dense are also populated by several endemic and threatened species. Despite many years of intensive management, high densities of G. paniculata persist in previously treated areas. To determine why this occurs, our research assessed current removal methods (foliar application of glyphosate and manual removal) by (1) measuring G. paniculata density and frequency over a large area using a point-intercept grid before and after treatment from 2016-2018, (2) investigating how timing of treatment affects G. paniculata density, (3) determining the resprout frequency of treated plants, (4) characterizing the local seed-maturation phenology and (5) investigating how timing of treatment affects resprouting and seed germination. Our results confirm that treatment for one or two years reduces the density of G. paniculata but does not extirpate it, overall treatment is most effective from late June through early July, and a small percentage of manually removed plants and herbicide-treated plants resprout following treatment. Seed germinability increased quickly at the end of July and reached a maximum of 90% or higher by early August in both 2016 and 2017.

The germinability of seeds from plants sprayed with glyphosate in early, mid, and late July 2016 was higher the later treatment was administered, highlighting the need to treat early in the growing season. To effectively control G. paniculata, we recommend that managers treat for consecutive years to remove regrowth and missed plants and focus treatment from late June to early July for best control, including prevention of seed maturation. Ultimately, this information will contribute to an adaptive management plan specific to baby’s breath that can be used in infested areas throughout northern North America.

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