Tom's Blog

Thursday, November 9, 2017

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