Year one results: Comparing seeding into brome grass sod that was first mowed and sprayed with glyphosate vs. seeding only

By Kevin Scheiwiller, Restoration Manager, Barrington Illinois

While attending the 2019 GRN Workshop in Madison, I was particularly impressed with the prairie restorations the Madison Audubon Society was undertaking. Young restorations of old brome fields already had a great display of matrix prairie species after just three years of planting. They had first burned and then sprayed glyphosate before seeding in the sod. After listening to how they approached these restorations, I was inspired to try a variation on their technique on some brome fields Citizens for Conservation recently acquired. In the past, we commonly would seed heavily into brome fields and rely on fire to eventually knock out the Eurasian grass sod. Anecdotal results using this approach for the last 10 years has had some positive results, but often a dense sod of brome will remain with only scattered clumps of native matrix species starting to break through. We decided to compare the two methods side by side and track the progression of each and make a quasi-experiment out of it.

Hypothesis:

Mow, then spray then seed Vs. Seed only: Stimulating growth of Hungarian Brome (Bromus inermis) through a late summer mowing followed by treatment of 3% Glyphosate in the Fall to set back the brome grass sod (as typically one spraying does not kill the sod but weakens it) will increase germination rates of prairie seedings over areas where brome is left intact.

Site Description:

The study site is an old hay meadow with the dominant species being Bromus inermis. There is scattered Tall Goldenrod (Solidago altissima) mixed in some of the study plots, but not in numbers that will drastically alter species composition.

Methods:

The site has been separated into 10 plots, 5 received Treatment 1 and 5 plots received Treatment 2. The study site is approximately 100’ by 170’. The plots were created by “eyeballing” the center point of the field on an East-West axis and creating study blocks every 30’ on the North-South axis. Figure 1 shows the study plots. A recent updated photo from Google maps reveals that the “eyeballing” techniques left plots rather uneven in shape and size. The center of each plot was staked with a wooden post for subsequent monitoring.

Treatment 1 – Mow, glyphosate, seed:

  • Areas mowed with a Gravely brand brush mower at a 4” depth on August 30, 2019. The mowing is meant to stimulate the growth of this cool season grass thereby increasing the uptake of herbicide. Madison Audubon Society uses late Summer burns for the same effect. Due to smoke concerns in a highly residential area, mowing was substituted for this experiment.
    • A 3% Glyphosate solution (4oz/gal of RoundUp Custom with 1oz/gal of non-ionic surfactant and turf marker) was applied a few weeks later on September 20, 2019.
    • Each plot seeded with 5 gallons of Dry Prairie Mix and perlite on November 20, 2019. The mix consisted of 9.3 ounces of 33 species of hand picked and processed (aka chaffy) seed mix. We seeded at an approximate rate of 17 pound per acre. See attached seed list for species and approximation of the weight distributed.  

Treatment 2 – Seed only:

  • Each plot seeded with the same 5 gallons of Dry Prairie Mix and perlite on November 20, 2019

Results after one Growing Season:

Plots were surveyed on September 13th, 2020 and a colleague, Karen Glennemeier, graciously crunched the data. The comparison between the two treatment types are as follows:

TreatmentPlotN SppMean CFQINative Cover% brome
mow, spray, seed1163.8815.50772
mow, spray, seed4174.4718.43980
mow, spray, seed5154.5317.56880
mow, spray, seed8135.2318.86850
mow, spray, seed9133.6213.04570
seed only230.330.581100
seed only351.804.0213100
seed only630.671.158100
seed only730.000.00090
seed only1050.801.795100
Means
mow, spray, seed14.804.3516.68810
seed only3.800.721.51598
St. Errors
mow, spray, seed0.800.281.0870
seed only0.490.300.7022

Management Implications and Ongoing Monitoring

As observed through the Madison Audubon’s restorations, the pre-treatment of Brome with mowing (or fire) and initial Glyphosate treatment produced a much more diverse assemblage of plants the following growing season. This treatment was not too intensive for the small plots but scaling up would require a large amount of time and/or equipment. The big question moving forward now is will the “Business as Usual” plots catch up to the treated plots? If both plots end up evening out in species abundance and distribution over the next decade, then is it worth the effort to pretreat the brome? Time will tell and data will continue to be collected.

Figure 1 –  Study Area: Plots 1,4,5,8,9 received mow, spray, and seed; Plots 2,3,6,7,10 received seed only

Figure 2 – Pretreatment August 30, 2019

Figure 3 – August 30, 2019 after mowing. 5 plots were mowed, sprayed with glyphosate 21 days later and then seeded. 5 plots were left unmowed but seeded same day as treatment

Figure 4 – November 20, 2019 Seeding each plot with ~5 gallons of Dry Prairie Mix

The author forgot to take a picture during the growing season of 2020 which would have been helpful for the sake of this article. The same error will not be repeated in 2021.

Dry Prairie Seed Mix broadcast on November 20, 2019

SpeciesCommon NameWeight per Plot (oz)
Allium cernuumNodding Wild Onion0.30
Anemone cylindricaThimbleweed0.07
Asclepias verticillataWhorled Milkweed0.01
Bouteloua curtipendulaSide-Oats Gramma0.38
Brachyelytrum erectumLong-Awned Wood Grass0.36
Brickellia eupatorioides corymbulosaFalse Boneset0.23
Cirsium discolorPasture thistle0.08
Coreoposis palmataPrairie Coreopsis0.23
Coreoposis tripterisTall Coreopsis0.06
Echinacea pallidaPale Purple Coneflower0.37
Eryngium yuccifoliumRattlesnake Master1.32
Gentiana andrewsiiBottle Gentian0.01
Liatris asperaRough Blazing Star0.07
Liatris spicataMarsh Blazing Star0.99
Oligoneuron rigidumStiff Goldenrod0.44
Parthenium integrifoliumWild Quinine0.41
Penstemon digitalisFoxglove Beard Tongue0.09
Ratibida pinnataYellow Coneflower0.26
Rudbeckia hirtaBlack-Eyed Susan0.22
Silphium integrifoliumRosin Weed0.19
Silphium laciniatumCompass Plant0.43
Silphium terebinthinaceumPrairie Dock0.05
Solidago junceaEarly Goldenrod0.01
Solidago nemoralisOld-Field Goldenrod0.03
Solidago speciosaShowy Goldenrod0.15
Sporobolus heterolepisPrairie Dropseed0.90
Symphyotrichum ericoidesHeath Aster0.02
Symphyotrichum laeveSmooth Blue Aster0.50
Symphyotrichum oolentangienseSky-Blue Aster0.48
Tradescantia ohiensisCommon Spiderwort0.50
Verbena strictaHoary Vervain0.01
Veronicastrum virginicumCulver’s Root0.07
Zizia aureaGolden Alexander0.06
This entry was posted in Uncategorized and tagged , , , , . Bookmark the permalink.

4 Responses to Year one results: Comparing seeding into brome grass sod that was first mowed and sprayed with glyphosate vs. seeding only

  1. prairiebotanist says:

    I don’t think this is long enough to show outcomes. See this presentation by Richard Henderson (TPE Volunteer Steward, retired WDNR). They have deployed seeding into brome with wild success over large areas, and he also shows some side by side strips of both approaches. It takes several years in concert with annual very early spring burning (to avoid seedling impacts), and its best deployed on dry-mesic to dry and generally less rich sites. It’s cut off a little at the beginning, but this talk is a must-watch. https://www.youtube.com/watch?v=hvMy–MMM2c&feature=emb_title

    • Kevin Scheiwiller says:

      Thanks Chris! It is absolutely not long enough to make any real conclusions from this little experiment. The next big question to answer is if and/or when will the “seed only” plots catch up in diversity. Another aspect we are interested in observing, is the burnability of the plots. It is very forb rich right now. Will this carry fire as well as the brome or take longer to be able to run a complete burn through?

      Citizens for Conservation has had luck with annual overseeding and burning into brome fields. It tends to take at least a decade until we observe an even distribution of our matrix species.

      I appreciate you sending this link to Rich’s presentation, looking forward to watching it!

  2. Bryon Walters says:

    Very interesting! If we don’t conduct experiments like this, we will never know the possibilities. For just “eyeballing it”, you guys did a great job on delineating plots! Good enough. My beliefs are that there will be some species drifting, both ways, from plot to plot. I am inclined on just doing a hard Glyphosate burn down on Brome before seeding. IMO- There is too much effort, labor and expense in broadcasting valuable native seed on a base of exotic turf grasses. I see no down side to doing a Glypho burn down. It only kills the current growing vegetation and any native seed that had been laying dormant for years, decades, will be unaffected, and will have a greater possibility of emerging. Anyway, keep us posted on your results and thanks for your efforts and sharing with us.

    • Kevin Scheiwiller says:

      That was our thought as well. We spend so much effort collecting and processing seed that we want to make sure we are taking the most efficient approach towards re-establishment.

      The only downside I have heard in the past would be a Glypho treatment could bring up a nasty weed infestation from the seed bank (particularly parsnip, sweet clover, or even worse bird’s foot trefoil). Seems to only make sense though to flush those weeds and beat back the seed bank as they will be in the restoration one way or another.

      This is a small experiment and will take many years to see if there are any true differences, but it’s a fun way to be able to visually and quantitatively compare methods!

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s