Babysbreath or perennial babysbreath (Gypsophila paniculata L.) is an aggressive invasive plant in large parts of southern Canada and the northern and western United States. It reproduces and disperses by seed, so the phenology of seed maturation is important in designing management programs. The present study provides the first quantitative assessment of G. paniculata seed-maturation phenology in a field population, as well as the first quantitative assessment of how the efficacy of herbicide treatment in preventing production of germinable seeds depends on the timing of treatment in relation to this phenology. Seeds were collected from untreated plants on five dates during July and August in both 2016 and 2017 and tested for germinability. Percent germination increased from 20% to 81% between July 22 and 28 and exceeded 90% by August 4, 2016. The seed-maturation phenology in 2017 was similar but delayed by about 4 d. On a growing degree-day scale, seed-maturation phenologies for the 2 yr were nearly identical. We also tested germinability of seeds from plants sprayed with glyphosate (23.4 ml ae L−1) on July 11, 18, and 25, 2016 (one date per plant). Percent germination increased from 0% to 13% to 20% over successive treatment dates, highlighting the importance of completing treatment early in the growing season.

Baby’s breath (Gypsophila paniculata L.) is an invasive species in Michigan’s northern lower peninsula and is a problem in much of northern North America. It is of particular concern in coastal dune habitats of northwest Michigan, because the areas where it is most dense are also populated by several endemic and threatened species. Current removal methods include manual removal with a spade and directed spray-to-wet foliar application of glyphosate to individual plants using backpack sprayers. We assessed these methods by measuring G. paniculata density and presence–absence frequency before and after treatment using a point-intercept grid, establishing how type and timing of treatment within the growing season influences treatment efficacy and determining the proportion of plants that resprout after treatment. Our results show a consistent reduction in G. paniculata density after treatment with herbicide or manual removal (P < 0.001) but minimal impact on presence–absence frequency. These results indicate a need for quantitative data in the assessment of management efficacy to show a clearer picture of density reduction when extirpation is no longer a viable outcome of management. Through the assessment of treatment timing of manual removal and glyphosate treatments over time, we found no evidence that either treatment type was effective at reducing density when applied before plants flowered, but there was evidence that both treatments were effective when applied later in the growing season when plants were flowering. Resprouting of marked plants occurred in 14% of manually removed plants and 2% of herbicide-treated plants. Our results suggest that managers should treat G. paniculata infestations for consecutive years to remove regrowth and focus treatment during flowering for best control.

Background Gypsophila paniculata (baby’s breath) is an invasive species found throughout much of the northwest United States and western Canada. Recently, plants exhibiting a different color morphology were identified within the coastal dunes along eastern Lake Michigan. The common baby’s breath (G. paniculata) typically produces stems that are purple in color (purple morph), while the atypical morph has stems that are green-yellow (green-yellow morph). The purpose of this study was to characterize these newly identified morphs and determine if they are genetically distinct species from the common baby’s breath in order to assess whether alternative management strategies should be employed to control these populations. Methods We sequenced two chloroplast regions, ribulose-bisphosphate carboxylase gene (rbcL), and maturase K (matK), and one nuclear region, internal transcribed spacer 2 (ITS2), from the purple morphs and green-yellow morphs collected from Sleeping Bear Dunes National Lakeshore, MI, USA (SBDNL). Sequences were aligned to reference sequences from other Gypsophila species obtained from the Barcode of Life Database and GenBank databases. We also collected seeds from wild purple morph and wild green-yellow morph plants in SBDNL. We grew the seeds in a common garden setting and characterized the proportion of green-yellow individuals produced from the two color morphs after 5-months of growth. Results Phylogenetic analyses based upon rbcL, matK, and ITS2 regions suggest that the two color morphs are not distinct species and they both belong to G. paniculata. Seeds collected from wild green-yellow morphs produced a significantly higher proportion of green-yellow individuals compared to the number produced by seeds collected from wild purple morphs. However, seeds collected from both color morphs produced more purple morphs than green-yellow morphs. Discussion Based upon these results, we propose that the two color morphs are variants of G. paniculata. Given the significant difference in the number of green-yellow morphs produced from the seeds of each morph type, we also suggest that this color difference has some genetic basis. We propose that current management continue to treat the two color morphs in a similar manner in terms of removal to prevent the further spread of this species.

14 Background. 15Gypsophila paniculata (baby's breath) is an invasive species found throughout much of the 16 northwest United States and western Canada. Recently, plants exhibiting a different color 17 morphology were identified within the coastal dunes along eastern Lake Michigan. The common 18 baby's breath (G. paniculata) typically produces stems that are purple in color (purple morph), 19 while the atypical morph has stems that are green-yellow (green-yellow morph). The purpose of 20 this study was to characterize these newly identified morphs and determine if they are genetically 21 distinct species from the common baby's breath in order to assess whether alternative 22 management strategies should be employed to control these populations. 23 2 24 Methods. We sequenced two chloroplast regions, rbcL and matK, and one nuclear region, ITS2, 25 from the purple morphs and green-yellow morphs collected from Sleeping Bear Dunes National 26 Lakeshore, MI, USA (SBDNL). Sequences were aligned to the reference sequences from other 27Gypsophila species obtained from the Barcode of Life (BOLD) and GenBank databases. We also 28 collected seeds from wild purple morph and wild green-yellow morph plants in SBDNL. We 29 grew the seeds in a common garden setting and characterized the proportion of green-yellow 30 individuals produced from the two color morphs after five-months of growth. 31 32Results. Phylogenetic analyses based upon rbcL, matK, and ITS2 regions suggest that the two 33 color morphs are not distinct species and they both belong to G. paniculata. Seeds collected from 34 wild green-yellow morphs produced a significantly higher proportion of green-yellow 35 individuals compared to the number produced by seeds collected from wild purple morphs. 36However, seeds collected from both color morphs produced more purple morphs than green-37 yellow morphs. 38 39 Discussion. Based upon these results, we propose that the two color morphs are variants of G. 40 paniculata. Given the significant difference in the number of green-yellow morphs produced 41 from the seeds of each morph type, we also suggest that this color difference has some genetic 42 basis. We propose that current management continue to treat the two color morphs in a similar 43 manner in terms of removal to prevent the further spread of this species. 44 45 46