Can Brambles Be Eradicated From Prairies and Savannas? A Long Story

Brambles (genus Rubus) may be native but they are
generally undesirable in a prairie or savanna. This post is based on over 20
years of restoration work at Pleasant Valley Conservancy.
The story starts when Kathie
and I first started clearing invasive brush and trees from prairie and savanna
remnants at PVC in 1997. There was lots of bad stuff: shrubs such as buckthorn,
honeysuckle, and prickly ash and trees such as elm, cedar, red pine (planted),
box elder. If there were brambles, we did not notice them. Probably they were
shade-suppressed.
But once the site was opened
up, brambles started to flourish. Originally they were just small patches, which
in our ignorance we ignored. In 1999 some of these bramble patches were large
enough that we got rid of them. There may have been some larger patches, but in
a property as large as Pleasant Valley Conservancy, it was easy to overlook
them.

What was the source of these brambles? Both buried
root stock and buried seeds are likely. I doubt the root stock is long lived,
but Rubus seeds are notoriously
long-lived. (A U.S. Forest Service study in New England found viable Rubus seeds that had been buried for 95
years.) 


The Ecology of Brambles
Brambles are members of the
genus Rubus. They have perennial
roots systems but biennial tops. The roots continue to spread but new canes are
formed each year. The first year cane just grows vegetatively and in the second
year flowers and forms fruits. After fruit formation it dies. Thus, a bramble
patch is a mixture of first year and second year canes, as well as dead canes
which senesce.
We have three species of Rubus at PVC: blackberries, black
raspberries, red raspberries. All are bad, and we do not distinguish between
them, although red raspberries presents a special challenge.

The First Survey

It was 2005 before brambles
started to be so obvious that we could not ignore them. That year I made a
survey, marking each patch with a numbered stake. There were 17 patches, all in
open savannas. My notes in the table here give some idea of how large these bramble
patches were.

Data from June 5-6 2005
Stake #
Unit #
Location
Notes
1
12A
~75 ft below the upper road (below Toby’s); large patch in
flower
White Oak Savanna
2
12A
~75 ft farther down the hill from #1; edge of Unit 12E;
large patch in flower
White Oak Savanna
3
12A
Smaller patch but taller stems west of #1
White Oak Savanna
4
12C
Large patch among two large dead oaks; also outliers east
and downhill
White Oak Savanna
5
12C
About 75 ft east of trail down; along a drainage; follow
the drainage up and down
White Oak Savanna
6
11A
Edge of open area and edge of ridge; shorter plants but
lots; forming berries
Bur Oak Savanna
7
11A
Near road; low but lots forming berries
Bur Oak Savanna
8
11A
50 fit West of #7 near fallen oak
Bur Oak Savanna
9
13B
Lots of 1st year plants mixed in with Geraniuum
etc. Can cut it all. Whole top of knoll, also
Woods near east property boundary
10
17
N of Toby’s in former aspen zone; scattered but large
patch; 1st year plants
Between Toby’s NE corner and woods
11
11B
Above Paul Ihm’s wood pile
Bur Oak Savanna
12
11A
SE corner of saddle; large patch with little good; mow up
hill and to the east also
Bur Oak Savanna
13
23
Large patch of low brambles; uphill to the west from the
saddle; do the whole patch
East-facing hill above Hickory Ravine
14
7
Very large patch uphill from Hickory Ravine; mow down hill
and to the east
15
6
Top of hill near fire break; 75 ft west of side road;
large patch of low brambles; mow down the hill and into the gully
16
10
Across the fire break from stake #15; big patch mixed in
with brush; cut it all and then treat the brush
Should have a second person with you for treating the cut
stumps
17
5C/5B
West of Unit 4 along and below the fire break on both
sides of the gully; huge area
This is a two-three person job!
Getting Serious
At that time the only
information I could find about how to eradicate brambles was: Mowing several times a year will reduce
their
vigor.
Reducing vigor did not sound
like a promising method for eradication.
By the late fall of 2005
Kathie and I had decided that our goal should be to get rid of all brambles, as
well as other invasive brush that had sprung up in our restored areas. After
all, we had spent a lot of effort opening up these prairies and savanna. If we
did not get rid of all these new invaders, we could be back where we started.
An awful thought!
We experimented with several
different methods of herbicide application: foliar spraying the bramble patches
(low herbicide concentration); basal bark (high concentration, in oil); cut and
treat the cut stems (high concentration, either aqueous of in oil). We rejected
foliar spraying of the large patches because of the possible peripheral herbicide
damage. We tried basal bark, but application from a backpack sprayer was also “wasterful”
of herbicide, and because of the high concentration, there were bare zones
around the treated patches. We also tried a sponge method for basal bark, but
the thorns on the brambles tore the sponges to shreds.
Cut-and-treat method
We chose the “cut-and-treat”
method because only small amounts of herbicide would be used, and it could be
applied carefully by a spray bottle. Because of the extent of the infestations,
this was usually a four- to five-person job. One person operated the Stihl
brush cutter and the others followed along with spray bottles containing 50%  glyphosate. Since we were working primarily in
the winter, when it was below freezing we diluted the glyphosate with
windshield washer fluid. Where there was a lot of buckthorn, we used Garlon 4
in oil, which presented no freezing problem in the winter. The “treaters”
fanned out behind the brush cutter and treated each cut stem.
A great advantage of this
method is that it could be done any time of year, and especially at times when
weed work, plant surveys, seed collecting, etc. could not be done. We worked
with a combination of hired employees and volunteers.
I ran some preliminary
versions of this method in late November 2005. We then set up a major effort on
the White Oak Savanna starting in early January 2006. Todd Shumate from Michler
& Brown ran the brush cutter and three or four “treaters” followed behind.
Todd cut every woody shrub in the savanna. Brambles constituted at least half of
the brush, but honeysuckle and prickly ash were substantial.
The brush cutter was equipped
with a saw blade. Todd ran the brush cutter until he ran out of gas (about 45
minutes per tank). He then sharpened the saw blade with a special Stihl file.
This kept the cut stems clean and flat so they could be treated properly. Cut
stems that were dead were not treated. (Living cut stems are green even in the
winter.)
The First Major Effort
The table gives an example of
this work for a five-acre white oak savanna. Finishing the whole unit took 9
days, working about 40 person hours per acre. Fortunately, January of 2006 was
surprisingly mild and snow-free. Often we were in shirt sleeves at noon.

Table shows brush cutting work on Unit 12A (the White Oak Savanna). Total area 5.3 acres
2-Feb-06
31-Jan-06
26-Jan-06
24-Jan-06
19-Jan-06
17-Jan-06
12-Jan-06
5-Jan-06
3-Jan-06
Totals
Todd
5.5
5.25
7
6.75
6.75
6.75
5.5
6.75
50.25
Susan
5.5
5.75
5.25
5.5
5.75
27.75
Elke
5.5
6
5.75
17.25
Tom
5.5
4.9
6
5.5
5.75
5.25
5.5
4
2
44.4
Kathie
5.5
4.9
6
5.5
5.75
5.25
5.5
5.75
2
46.15
Brian
2.25
4.25
2
8.5
Final total
194.3
Averages>>
36.7
hrs/acre
If assume $25/hr, acreage cost is
$917.50
Roughly $1000/acre



Extending the Effort (2006-2007)
Once the White Oak Savanna
work was completed, we extended the work to the rest of the areas where brush
and brambles were rampant. The table shows the 2006-2007 work (81 work days; 30
days in 2006 and 51 days in 2007.)
In 2007 I established winter
intern positions, and we had 3 (or 4) UW-Madison students working two days a
week starting in January and continuing until mid May.

Date
Unit
Notes
7
Feb 2006
18
Lots
of honeysuckle; brambles; prickly ash; walnut resprouts
9
Feb 2006
18
Lots
of honeysuckle; brambles; prickly ash; walnut resprouts
14
February 2006
18
Lots
of honeysuckle; brambles; prickly ash; walnut resprouts
21
Feb 2006
6
Mostly
honeys; small buckth; few brmbles; some dogwood
23
Feb 2006
2
below Diag Trail
Lots
honeys few buckth; fee brmbles
28
Feb 2006
12B
Mostly
brambles
2
Mar 2006
12B
7
Mar 2006
3
(around big bur oak)
Mostly
brambles
7
Mar 2006
19C
Buckth
mostly
10
Mar 2006
6/23
Lots
little buckth
11
Mar 2006
6/23
14
Mar 2006
11
Big
bramble; buckth; prickly ash
21
Mar 2006
11
23
Mar 2006
10
Lots
tiny buckth; brambles
28
Mar 2006
6
(east)
Honeys;
brambles; s umac
30
Mar 2006
19
17
Nov 2006
7
Lower
part and adjacent to 18; shrubs/brambles small honeys; cut & treat glypho
19
Nov 2006
7
small
honeys buckth brambles; few walnuts
21
Nov 2006
7
27
Nov 2006
Lots
of notes about cut & treat and then plant
30
Nov 2006
3/6
Gully
above big bur; lots brambles; some honeys; few buckth; grape
5
Dec 2006
6/9
Gully
between 6 & 9; see record for details of how we did it
12
Dec 2006
6/9
top
of gully; gray dogw
15
Dec 2006
6/9
Continue
from 12 Dec
17
Dec 2006
12A
Check
for brush/bramble problems; 9 areas listed; mostly brambles (all 3 spp)
19
Dec 2006
6/9
gully/brambles
26
Dec 2006
6
gully
below S fire break; 
28
Dec 2006
6
Finish
unit 6
28
Dec 2006
3/9
above
gully
2
Jan 2007
5
Up
to fire break
2
Jan 2007
3
3
Jan 2007
4/9
Winter
interns; paint stick!
4
Jan 2007
3/4/9
lots
of honeys on Unit 9; walnuts; Autumn olive!
8
Jan 2007
19A
Top,
near Toby’s; Chris instead of Todd
9
Jan 2007
3/4/9
10
Jan 2007
3/5
gully
above diagonal trail
11
Jan 2007
5B/C
15
Jan 2007
20
near
Pocket Prairie; snowed 5 inches the day before; worked anyway
17
Jan 2007
20
Also
bur oak grove near chain
18
Jan 2007
20
Along
woods road; lots blackberry lots hazel elderberry
22
Jan 2007
20
24
Jan 2007
20
Finish
Unit 20
25
Jan 2007
21
snow
too deep move to top of hill
26
Jan 2007
20
29
Jan 2007
21
West
of Ridge Prairie
30
Jan 2007
too
cold, did not work
31
Jan 2007
21
snow
mostly gone
1
Feb 2007
21
Just
T & K
5
Feb 2007
Below
zero in morning; work cancelled all week
12
Feb 2007
12A
Lots
of dead buckth but some alive
13
Feb 2007
19E/11E
19E
too windy; moved to 11D
14
Feb 2007
11D
15
Feb 2007
11D
large
blackberry patch; Mid Savanna Trail
16
Feb 2007
11D
finished
this unit
19
Feb 2007
2
gully
above 2 bur oaks
20
Feb 2007
2/3
finish
gully up to fire break; lots sumac; some honeys; some buckth; rare bramble
21
Feb 2007
2
above
diagonal trail
22
Feb 2007
2
above
diagonal trail
26
Feb 2007
7
Lower
& middle on west side
27
Feb 007
7
Middle
& upper; around East Overlook rocks
28
Feb 2007
6/7
Up
from Hickory Ravine into Unit 6
2
Mar 2007
Ravine
Ravine
between 12A and 20B; lots of snow drifts!
5
Mar 2007
14
Corner
PV Rd &  Cty F; snow deep!
5
Mar 2007
1
Less
snow; road cut for Unit 1
6
Mar 2007
5A
6
Mar 2007
20B
after
lunch finish 20B
7
Mar 2007
14
below
quarry
8
Mar 2007
5A
Up
to Ridge Trail
8
Mar 2007
6
Afer
lunch, 5A too sloppy, moved to 6 lower east around rocks, lots of honeys but
small
12
Mar 2007
5A
13
Mar 2007
5A
Above
Unit 1 and along Ridge Trail; FINISH WHOLE SOUTH SLOPE!!
13
Mar 2007
Quarry
After
lunch
14
Mar 2007
2/19
Finish
Unit 2; start Unit 19
15
Mar 2007
6
along
dolomite shelf
15
Mar 2007
19
20
Mar 2007
19D/E
22
March2007
19C/D
28
Mar 2007
20C/19D
Finish
20C
4
Apr 2007
19C
5
Apr 2007
19C

Fire and Brambles: Spraying Resprouts
Brambles are fairly fire
sensitive and are killed by a controlled burn.
Fire moving through a bramble patch in a savanna. All  bramble stems are killed.


Starting in 2008 we added
another method of bramble control: foliar
spraying of resprouts
after the bramble canes had been killed by early
spring burns. The details of this method are covered in several Tom’s Blog
posts in 2008, 2009, and 2010.
Although this method is very effective,
it is limited to May or early June, when the resprouts are small enough to
spray without too much peripheral damage. To set up the spraying routine, I
created another bramble database. By then I had learned how to  use ArcGIS. On 14 and 16 April 2009 I walked
the whole south side of PVC, recording the coordinates of each patch
After a burn, bramble patches
are fairly easy to spot, as the following photo shows.

Large bramble patch easily seen after a spring burn. Unit 11B; red raspberry patch
Typical resprouts after the brambles have been top-killed by fire; Mid-May
Spraying bramble resprouts about mid-May. Any other woody invasives such as
buckthorn or honeysuckle are also sprayed. Often a crew of 4-5  would work on the same unit
Table used to create an ArcGIS map of brambles. The date burned was used to determine which units to spray first.

Patch
Lat
Lon
Unit
Species
Date
burned
Priority
Notes
1
43.10559567
-89.80980858
Cabin
Blackberry
4/3/2009
1
Small
2
43.10625558
-89.81188151
Crane
Blackberry
4/3/2009
2
Moderate
3
43.10738856
-89.81244938
Crane
Blackberry
4/3/2009
6
Huge!
4
43.10493216
-89.80763666
Valley
Blackberry
4/3/2009
4
Large
in line
5
43.10473401
-89.80720634
Valley
Blackberry
4/3/2009
1
Small
6
43.10489771
-89.80679244
Unit
7
Red
raspberry
3/19/2009
4
Large-blackberry
+ red raspberry
7
43.106673
-89.80296275
Unit
12B
Black
raspberry
4/8/2009
2
Moderate
8
43.10670745
-89.80279796
Unit
12B
Black
raspberry
4/8/2009
2
Moderate
9
43.10649136
-89.8028195
Unit
12A
Red
raspberry
4/8/2009
3
Both
red and black raspberry
10
43.10642933
-89.80255279
Unit
12A
Red
raspberry
4/8/2009
6
Huge!–also
hazel
11
43.10747255
-89.80242924
Unit
19E
Black
raspberry
4/3/2009
3
Loose
patches scattered
12
43.10759794
-89.80236797
Unit
19E
Blackberry
4/3/2009
1
Small
plus burdock
13
43.10737649
-89.80267533
Unit
19E
Black
raspberry
4/3/2009
1
Small,
near road
14
43.10721648
-89.80272344
Unit
11B
Red
raspberry
4/8/2009
2
By
road, across from 19E, linear along road
15
43.10718882
-89.80436982
Unit
11B
Red
raspberry
4/8/2009
6
Very
large! Also clone S and W of AP1
16
43.10696955
-89.8050278
Unit
11B
Red
raspberry
4/8/2009
6
Very
large clone around stake AP2
17
43.10694985
-89.80539626
Unit
11A
Red
raspberry
4/8/2009
6
Very
large clone around stake AP3
18
43.10729401
-89.80591837
Unit
19C
Red
raspberry
4/8/2009
5
Large
clone near road
19
43.10664257
-89.80375467
Unit
11D
Blackberry
4/8/2009
2
100
feet W of Junction of the two trails
20
43.1063953
-89.80440527
Unit
11D
Red
raspberry
4/8/2009
5
In
middle of unit, large clone
21
43.10640126
-89.80471448
Unit
11D
Red
raspberry
4/8/2009
3
In
middle, farther toward gully than BR20
22
43.10649178
-89.80462773
Unit
11D
Red
raspberry
4/8/2009
1
25
ft S of Mid Sav Trail; Small clone
23
43.10664115
-89.80473007
Unit
11C
Red
raspberry
4/8/2009
1
Above
Mid Sav, near trail, near large hickory; small clone
24
43.10663964
-89.80479612
Unit
11C
Red
raspberry
4/8/2009
1
Small
clone, short stems, above Mid Sav
25
43.10649354
-89.80546198
Unit
11C
Blackberry
4/8/2009
3
Near
Mid Sav and just E of large white oak
26
43.10438147
-89.80366163
Unit
20
Black
raspberry
4/18/2009
6
By
woods road, very large clone
27
43.10416186
-89.80353146
Unit
21
Black
raspberry
4/18/2009
1
Fairly
small, near woods road
28
43.10581922
-89.79962222
Unit
13
Black
raspberry
4/8/2009
6
Top
of knoll, very large clone, also down all sides
29
43.10412599
-89.80182314
Unit
21
Black
raspberry
4/18/2009
1
At
S end of Ridge Prairie, smallclone
30
43.10433671
-89.801943
Unit
21
Black
raspberry
4/18/2009
3
West
of BR29, larger, fairly loose clone
31
43.10670761
-89.79977419
Unit
13
Black
raspberry
4/8/2009
5
N
side, down hill from knoll and near fire break separating Toby’s N; very
large but loose
32
43.10691012
-89.79992732
Toby’s
N aspen
Blackberry
4/18/2009
1
Near
fire break to Unit 13, small
33
43.10757849
-89.80411207
Unit
19D
Red
raspberry
4/8/2009
3
Middle
betw woods road and N fire break, med-sized clone
34
43.10703333
-89.80819951
Unit
10
Black
raspberry
4/8/2009
1
Near
road and bur oak #704,fairly small clone
35
43.10691431
-89.8089574
Unit
8
Black
raspberry
4/8/2009
1
Near
Parking, small clone near downed logs
36
43.1066963
-89.8089258
Unit
8
Black
raspberry
4/8/2009
6
Very
large loose clone; lower SE side of unit
37
43.10709964
-89.8086979
Unit
19B
Black
raspberry
4/8/2009
5
fairly
large, near end road and AP-8
38
43.10714708
-89.80853898
Unit
19B
Black
raspberry
4/8/2009
6
very
large, up from N fire break and E of AP-8
39
43.10716728
-89.80809876
Unit
19B
Red
raspberry
4/8/2009
1
small
clone by road
40
43.10708078
-89.80763918
Unit
19B
Red
raspberry
4/8/2009
6
very
large clones of all three spp., between woods road and N fire break–MAJOR
JOB
41
43.10713316
-89.80734958
Unit
19B
Black
raspberry
4/8/2009
5
Large
patch, about 1/2 did not burn
42
43.10599859
-89.80708379
Unit
23
Black
raspberry
3/19/2009
1
Near
saddle road; may have been sprayed?
43
43.10604746
-89.80672413
Unit
11A
Black
raspberry
4/8/2009
6
Up
from saddle road, E of AP stake, very large clones almost merging; runs NE/SW
along the edge of the ridge, about 15 ft E of AP stake
46
43.10588418
-89.8065357
Unit
11A
Black
raspberry
4/8/2009
2
Downhill
from BR43, right next to saddle road; smallish clone
47
43.10568452
-89.8063311
Unit
11A
Black
raspberry
4/8/2009
6
Very
large clone between saddle road and Mid Sav Trail; all day job for 1 person!!
48
43.1054303
-89.80646202
Unit
7
Red
raspberry
3/19/2009
5
Below
saddle road;large scattered loose; from Hickory Ravine to rock outcrop
49
43.10424141
-89.80488572
Valley
Black
raspberry
4/3/2009
3
Far
E end by fire break; narrow patch along break; also some East of the fire
break
50
43.10448431
-89.80189255
Unit
21
Black
raspberry
4/18/2009
5
Near
top, W of Ridge Prairie; large; good area to plant
51
43.10472043
-89.80143623
Unit
21
Blackberry
4/18/2009
2
Moderate
52
43.10612004
-89.80752091
Unit
6
Black
raspberry
3/19/2009
2
Top
of gully near S fire break; moderate
53
43.10624929
-89.80765586
Unit
6
Black
raspberry
3/19/2009
5
Up
from gully near bur oak grove; large loose clone
54
43.10630059
-89.80788318
Unit
6
Black
raspberry
3/19/2009
2
Nearer
gully than BR53, mixed in with sumac

By the beginning of 2010 we
had fairly good control of brambles except for red raspberry, which forms really
dense patches of brambles with stems growing very close together. The cut-and
-treat method is not recommended because the cut stems are so close together
and it is difficult to keep track of which ones had been treated. Fortunately,
most of the areas where we were cutting and treating did not have red
raspberries.
After almost ten years
working on bramble control, I found that the best way to control red raspberry is to spray (with 3.5% aqueous Garlon 3A) all
the resprouts that arise after burns. However, not all shoots come up at the
same time, so it is necessary to spray again two weeks after the first time,
and again after another two weeks. Monitoring again in mid-summer for any “escapes”,
and again the next year is also advisable.
The importance of annual burns
One of the most important reasons
why annual burns should be done in oak savannas is because of brambles. Putting
savannas on a three-year burn cycle, such as is often done for prairies, is
exceedingly ill advised. Savannas almost always have a “legacy” of woody
invasives, of which brambles are one of the most important. Giving woody
vegetation the chance to grow unimpeded for three years does serious damage to
the herbaceous understory. In addition, the savanna will not carry a fire well
with all those woody shrubs hogging the savanna floor.
We have been burning our
savannas annually for 15 years (since 2002).
The best time to search for
undesirable woody plants is after a burn. This photo, of the Unit 10 savanna,
was taken on March 28, 2017 (the spring burn had been done on Feb 22, 2017).
Note the absence of woody vegetation (except for the blow-downs). You could
walk from one end of this savanna to the other without encountering a single
obstacle. Compare with the 2008 photo shown above.

Bur oak savanna after 15 annual burns
Note the absence of woody invasives

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