June 28, 2008
My experiment with biological control of Canada Thistles in prairie restorations is showing modest signs of progress. This involved finding thistles with signs of a bacterial infection that produces chloresis, turning the thistle to the color of beeswax and generally sickening the shoot. After collecting two of these in 2006, I liquified them in a blender, added water and a few drops of Dawn dishwashing detergent to act as a surfactant and sprayed the liquid on two small colonies of thistles in the restoration. The following year there were several dozen shoots with chloresis, so I gathered more of them and repeated the process, spraying thistles randomly throughout the prairie restoration.
Below is shown an individual Canada Thistle shoot with the chloresis symptom of infection. The chloresis appears to start near the top of the shoot and to work its way down the plant.
About mid-June of this year I noted that there are now pallid thistle shoots to be found throughout the field. Several colonies were intensely affected to the point that it looked like the colony might die out. Few of the shoots were setting seed heads in the most affected groups. Other areas showed thistles turning white, but still growing. Most of the chloresis seems not to appear until around mid-June. I saw isolated affected shoots earlier.
Canada Thistles grow in colonies. The shoots are connected by the underground root system. In theory if you infect one shoot, the entire colony should become infected. Below is a photo of a colony in which many of the shoots are showing the signs of infection. Note that some shoots still appear healthy.
I have, by no means, won the battle against Canada Thistles. While there are now hundreds of ill shoots in the field, there are hundreds of healthy looking thistles for every sick one, and I've been systematically going through the field to remove their tops with a weed whacker before they produce seed.
However, it is very promising that the amount of diseased thistle foliage has grown so much in one year. My efforts are based on research experiments being conducted at several universities, including the U of Minnesota. The pdf file available at the following link should be of great interest to prairie restorationists battling Canada Thistles.
http://www.cts.umn.edu/Publications/ResearchReports/reportdetail.html?id=1504
From what I have read, it appears that the surfactant used has an effect on how infectious the liquid will be. Having no access to the surfactants used in the experiments, I am using Dawn dishwashing detergent, which is the surfactant I have.
I repeated application of the spray today under wet and overcast conditions with cool temperatures. I used about a half dozen infected plants gathered from throughout the prairie restoration.
Those interested in trying these techniques can contact me by email for more information. The best time to apply the spray is mid June through mid July according to one source I've read. It is also best to apply the bacteria under wet conditions. I have also read that the strains of this infection are of variable lethality. Some may only sicken a few shoots and others may destroy entire colonies.
May 7, 2008
I contacted Prairie Restorations this past winter about doing a controlled burn, but as I walked the field I could see that the areas that most need a burn--the west and east edges of the field--didn't have the fuel to carry a fire consistently. It was decided to wait until next year for the burn. The dry conditions which caused the reduced vegetation in the weedy areas were good for the prairie overall. Weeds were much less able to compete with the natives and the amount of Giant Ragweed in particular was a small fraction of what it was the year before on those partially shaded edges.
A few years ago we had a dense stand of common Goldenrod in an area roughly 50' x 150'. The area appeared to be composed of Goldenrod and almost no other plants of any sort. What I was reading from a couple of prairie restoration sources was that this would likely be a 15 to 20 year problem. This has not been the case with our stand. The Goldenrod are now scattered and prairie species are showing up strongly, especially Purple Coneflower, Canada Wild Rye and warm season grasses. While we still have the common Goldenrod, it is in very reasonable amounts, i.e. it seems to have found its niche in the community.
With vivid memories of our fire last spring, I mowed gigantic firebreaks around the prairie last November, mostly in the 40' to 50' range. The southwest corner of the prairie which contains the interseeded areas was burned (by me) on May 5th. This is an area of 50' by 100'. Immediately north of that is a 40' mowed firebreak (it performed very well, but I had the hose on hand just in case!), and north of that is the main prairie, unmowed and unburned. Each area has been marked with flags so it will be interesting to see what differences are obvious in the coming growing season.
Below is a Spiderwort in bloom.
December 31, 2007
We added a couple of Leadplants and a White Indigo as bare root plants, and they seem to have established themselves. Purple Coneflowers are more numerous than in the past, and Switchgrass seems to have given some ground to the other tallgrasses. I again collected seed from a number of species for distribution in areas needing more native species.
Below is a photo of our main prairie area in winter.
July 28, 2007
I burned the interseeded test area in two sessions during April.
Prairie Restorations again performed a burn on the rest of our prairie this May. There was already a lot of greenery visible in the field. The day was dry and blustery and the east and west edges did not burn well. We shot some film and video footage during the burn and examined it briefly after the crew left. After half an hour, I went out to burn some of the smaller areas that had not ignited, and was soon surprised to see a substantial fire in the woodland adjacent to the northwest corner of the prairie. This fire got into some brushpiles and then some decaying aspen logs and gave me the hardest workout I'd had in years. It took nearly four hours to extinguish the blaze entirely. I learned a lesson. After the crew leaves, walk the perimeter continually for a couple of hours. A tiny fire is easy to put out; not so a fire that has 8 foot flames with strong winds, low humidity and lots of adjacent fuel!
My experiment last year with introducing Canada Thistle plants to the bacteria pneumonae syringae appears to have had some success. By early July this year there were shoots exhibiting the chlorosis symptom in both of the test areas and several other parts of the prairie. I found one or more diseased thistle in about a dozen colonies. The diseased thistles probably amounted to less than 100 shoots. I decided to gather several of these and repeat the procedure, spraying the solution in areas throughout the prairie where I could find Canada Thistle shoots. The prairie was quite wet with dew when I sprayed, but the day heated up by late morning. Below is a photo of a colony of infected thistles.
It has been very dry this growing season. We just received 1" of rain yesterday, and the area is still classified as being in moderate drought. Corn has begun to appear stressed and the lawns are totally dormant except for weeds. The prairie looks great. The Giant Ragweed is not conquering the edges this year. Last year at this time it was towering over all on the western edge. This year the Big Bluestem is king through the field, except for numerous Compass Plants up to 8 feet tall.
December 20, 2006
Prairie Restorations performed a burn on May 10th which dealt a good
blow to the Reed Canary grass invading the southeast edge. The burn
was total and intense in most of the prairie except for the southwest
corner and some of the western side. The vegetation was a bit too
sparse in the southwest corner to keep a sustained fire going, so I
went through and spot burned a few of the areas that escaped. Overall
it was a good burn. Dave Huffman thought another burn next spring
might stimulate the grasses along the western side. This is the area
partly shaded by late afternoon due to trees to the west. The Giant
Ragweed loves this area. After the burn I mowed down all remaining
vegetation with the 8N Ford and the bushwhacker.
Rainfall was average this growing season. We had some wet times in which the little swale was as full as it can get. The latter half of the summer was drier, and the fall was quite dry. The grasses came up extremely robustly. And soon, so did the Canada Thistles! I began my crusade with spot treatment of Roundup via a painter's sponge, but felt it was far more than I could do in the small window of opportunity I had before the grasses got in the way of the job.
Since I was out of my league with the spot treatment solution I did some research and learned of experiments at sickening Canada Thistle by grinding up sick plants with water and adding a surfactant. I located a couple thistle plants that had the chlorosis symptom and put them in a blender with water, then added a few drops of Dawn dish detergent--the only surfactant I had at hand. I began spraying a few test areas with a spray bottle which quickly clogged. I got a second spray bottle that handled the brew and finished spreading my biological weapon. I sprayed in late afternoon on a day with high humidity. The spray was not too successful. I found a few infected thistles in the areas within the next two weeks, but most of the plants seemed to thrive as well as unsprayed thistles. According to my readings, the surfactant used is an important factor, so that may be the cause of my poor results. I did feel encouraged that at least a few thistles looked extremely ill (a few actually died). So there is hope that I have at least spread the thistle disease in this planting.
The grasses grew so thickly and heavily that the majority of the thistles were left in the dark. They lost their robustness to a great extent as the season progressed, and it appears to me that the best way to control Canada Thistles in a reconstruction on fertile soil is to encourage the grasses with burns. I have also read this year of research indicating that Roundup has been having negative consequences for amphibians, contrary to earlier studies. So I may not even do a lot of spot treating with Roundup next season.
After the spring burn, we scattered all the seed collected the previous fall. We also added several live plants--Leadplant, Alumroot and White Indigo. We noted much stronger Rattlesnake Master growth this year, and we saw many new Purple Coneflower individuals flowering. There were not so many Liatris and very few Long-Headed Coneflowers. The Turtleheads have become established nicely along the eastern edge in the wettest part of the main planting.
December 24, 2005
2005 had adequate moisture throughout the growing season. We had a lot
of giant ragweed throughout roughly half of the field. On the western
side, which gets some afternoon shade from western treeline, it was
very thick, so I weedwhacked when the plants were about 4 feet tall.
This set it back, however most of the prairie plants also seemed
inhibited in the worst areas. The grasses are in the area, but not
dominating where they have the competition from ragweed (also one
smaller area dominated by Canadian Goldenrod). Bob from Prairie
Restorations says often a second fire will allow grasses to flourish.
He is of the opinion that after this burn, no burning should be done
for a number of years.
The Canada Thistle situation is static. I was able to do virtually no herbiciding because of the old growth hiding thistles until everything was a thick jungle. I pulled and cut thistles where I came across them, making an effort to keep as many as possible from setting seed. I got lots of them, but difficult as they were to spot, it's certain that lots of them went to seed. There were not any dense patches of thistles, however, and where I found groups, I attacked them. I don't think the thistles are getting the upper hand over the prairie plants. Nonetheless, they are widely evident, and I plan to hit them hard again with Roundup after the spring burn. I may do a small experiment with a tougher thistle herbicide as well. Roundup top kills but doesn't wipe out the underground parts. They come back stunted and weaker if you hit the colonies several times in a season as I did the southwest corner. That area continues to have far fewer thistles despite no Roundup use there this year (I handpulled any I found).
The prairie was not as showy this year. The previous year's debris hid things until the new growth was quite tall and some species such as Rattlesnake Master were quite puny compared to their robust growth the previous year. The grasses finally had the upper hand in the open full-sun areas. Still no blooms from the Compass Plants, but they did put out some larger leaves late in the growing season. The small swale had a great year with several species making a first appearance. The woodland grasses experimental plot also appears to be on track. See their individual files for more on all the smaller, unique areas and experiments.
May 26, 2005
We made arrangements with the South Bend Township Volunteer Fire
Department to do a controlled burn on our prairie this spring. Having
seen nothing occur as of early May, I contacted them again and learned
they thought conditions had been too dry, even though we were under no
burning restrictions in Blue Earth County. The contact person said
that a mid-summer burn might be possible. I turned that offer down.
Part of the prairie is under CRP contract and burns are prohibited
during the prime nesting season. I also felt it would be unduly hard on
the prairie plants to burn in mid-summer (if the field could be made to
burn at all). I contacted Prairie Restorations to discuss a burn next
spring. They will examine the field in June. If Prairie Restorations
turns out to not be a good option, I have just purchased a Woods brush
mower for my Ford 8N tractor, and I'll mow off all the debris next
spring.
After the dry month of April, May has proved to be a washout. The soil is thoroughly saturated and the little swale we created had standing water for most of the month. The Turtleheads should have a great year.
I examined the field today. The field is greening up under its coat of tall dead stalks from last year. The Canada Thistles are about as evident as they were last year after the spring burn. I guess I'll take my Roundup out there and try to kill at least some of them! The Cup Plants and Prairie Dock plants I set out last year are looking robust.
The woodland grasses test plot seeded last fall is looking very encouraging so far. I weedwhacked off the overstory once and see little grass plants throughout the area. I grew a few indoors this spring and set out the 3 survivors so as to have a reference when the plot plants get larger.
I also started some other prairie plants including Prairie Moon Pale Purple Coneflower, Prairie Moon Copper Shouldered Oval Sedge, Kasota Prairie Dropseed and LeHillier Big Bluestem. Some of each are in the little raised garden prairie and the rest are or will be planted on the margins of the main prairie.
The Toy lawn prairie looks great except for still being infested with the supposed Western Obedient Plant. I'll have to attack with Roundup.
The Sweetgrass is not doing well in its present location on the lawn, so I moved some to a wet area of the prairie. It began to rain until a pool formed and then a deer smashed the area with its feet. Back to the drawing board.
November 16, 2004
This past weekend we mixed gathered seed and distributed it in spots
where there is little evidence of prairie species. The field
perimeter, which is partially shaded by adjacent trees east and west of
the field, is the only real problem area. I also raked, cleared and
seeded small areas in the grove east of the field. We have discovered
Cup Plant and a wild rye growing in one spot, and the grove is getting
more sun lately since many of the trees are 40 year old elms in the
process of dying from Dutch Elm disease. Here is a list of the species
planted in these areas: Black Eyed Susan, Cup Plant, Purple
Coneflower, Hoary Vervain, Prairie Cinquefoil, Rattlesnake Master, Gray
Headed Coneflower, Long Headed Coneflower, Wild Bergamot, Ox Eye,
Yarrow, Maximilian Sunflower, Large Flowered Penstemon, Showy
Goldenrod, Switch Grass, Indian Grass, Big Bluestem, Little Bluestem,
Side Oats Grama and Canada Rye.
We also began a woodland grasses test plot, 25' x 25'. This is also in the east grove. The area was raked clear of leaves. There was little vegetation except for some woodland phlox. We planted 1 oz. Bottlebrush Grass, 1 oz. Hairy Wood Chess, 1 oz. Silky Wild Rye, 1 oz Virginia Wild Rye, 1 oz. Beak Grass, 1 packet Straight-Styled Wood Sedge and 1 packet Long-Beaked Sedge. All seed for this was from Prairie Moon Nursery.
We noted some more species in the prairie this growing season and photographed many species to add to this website this winter as soon as time permits. The growing season was quite wet at times and we had quite a lot of Giant Ragweed growing on the western side. The Canada Thistle stayed fairly controlled after my walk through the field with Roundup this spring, but the plants are still easily to be found. Many were stunted and there were some that went to seed, but there are no large or dense colonies. I plan on walking the field again next spring after the burn.
May 28, 2004
After a dry winter and a dryer spring, May has begun to even things up.
I've measured about 5.5 inches of rain this month.
After the burn, I walked the field in 6 foot widths with a spray bottle of Roundup, spraying every Canadian Thistle I could find. There were plenty of them! I began a second pass as soon as I finished the first pass in early May and have gotten about 1/3 of the field walked. However, the density of vegetation is beginning to really slow me down. The plants I hit the first time were dead or sickly, however the colonies are either sending up new volunteers or I missed a lot of thistles. If vegetation gets too dense, I may quit spraying and wait til seedheads are emerging and cut off the thistles about 10 inches up their stalks--a couple sources report that this technique will not send the thistle colony messages to have the cut plant grow new seedheads. But I'm also going to look for other ways to control these plants. I was very chagrinned to learn that the "cockleburr" I sprayed last week was a robust Cup Plant--one of only two specimens I've seen in the field. I did grow some Cup Plants from seed and plant them out into the prairie, but I have a couple years to wait til they turn into big, strong plants like the two that volunteered (I have no record of having included Cup Plant in the seeding of the field).
I started a number of prairie plants indoors in March and ended up with about 40 plants which I planted out into the prairie in early May. The species included Butterfly Weed (the local LeHillier seeds),Ironweed, Boneset, Royal Catchfly, Cup Plant, Prairie Dock, Sullivant's Milkweed, Whorled Milkweed, Purple Prairie Clover, White Prairie Clover and Wild Quinine. A few plants went to the toy prairies on the lawn & dry garden corner.
Last year I planted a Western Obedient plant I'd grown from seed in the little toy prairie on the lawn. Never again. This plant sends rhizomes everywhere which put up shoots over the entire area of this little prairie garden (about 6' x 6'). I keep pinching off shoots, but it keeps coming. Not even Roundup does much more than affect the sprayed shoot.
We are keeping an inventory of species discovered, which I'll try to get posted soon.
April 12, 2004
The DNR crew performed the controlled burn today(See photos). The
weather has been very dry and there was some doubt whether burning
could take place, but the weather conditions created an opportunity.
Winds were from the southeast with infrequent, sudden changes. The
field was burned in sections from north to south. After a backfire had
been burned, a strip 50 or 75 feet wide was ignited and allowed to burn
back to the north. Backfires were maintained on the western edge. The
whole burn took about 40 minutes. Randy and his crew did a great job.
Some scattered stalks of tall plants remained in places due to
insufficient fuel, but the burn covered the whole field with only a few
tiny areas of sparse vegetation escaping the flames.
November 23, 2003
The new area (the interseed experiment and the seed nursery area) were
seeded last weekend. We added several additional species this weekend.
Also I added some seed to the main prairie which Jo-Ann and I had
collected and processed. I worked this in with a garden rake to small
areas which had little vegetation. We had several ounces of
Large-flowered Beardtongue (Penstemon), about an ounce of Cinquefoil,
an ounce of Golden Alexanders and a half ounce of Whorled Milkweed. At
first we were concerned about adding this last one, since one of our
books listed it as hazardous to livestock. However, I checked with
Randy from the DNR, and he said the deer and cattle avoid this plant.
We were particularly excited to get some rather rare seed from Randy, the Sullivant's (sometimes called Sullivan's) Milkweed. I planted this in two areas I can easily watch, and saved a few seeds to stratify and start indoors. There's quite a list of seeds we're going to start indoors (around March), and so in the next week or two we'll put them in moistened sand and refrigerate them.
Before I was done scattering our seed on Saturday, the first large snowstorm of the season began; I think we timed the seeding just right!
September 3, 2003
Stiff Goldenrod, asters and Blazing Star are the primary blooms. The
edges of the large planting are quite weedy with Giant Ragweed,
Canadian Goldenrod and an annoying weed with hundreds of small burrs!
Randy Schindle, the DNR officer overlooking my planting feels that the
spring burn will improve things greatly. In most of the field, the
grasses are quite robust. Indian Grass is now the most visible. We
harvested some penstemon grandiflorus seed, prairie Cinquefoil, Poppy
Mallow, Golden Alexander and Canadian Vetch seed. In my toy prairie on
the front lawn (a 4' x 4' plot I planted this spring), purple
coneflowers are blooming wildly, as is an unknown plant which is
certainly some other sort of coneflower. The Western Obedient plant is
thriving as are the Cinquefoils, Butterfly Milkweed and Blazing Star
specimens. Most of the grasses are doing very well. I've learned that
I planted my babies too close together! I grew most of these from seed
started inside last February and spaced them 6 inches apart in the
garden, figuring that many of the frail babies wouldn't make it! Very
wrong! All but a couple Blazing Stars lived! Grasses include Little
Bluestem, Sideoats Grama, Northern Dropseed, Blue Grama and a mystery
bunching grass I believe to be Junegrass.
July 15, 2003
I have a large backlog of photos to scan and put up. We spotted a
suspected Purple Loostrife plant; not being positive, I clipped all the
flowering area and left the rest of the plant for now. The Canada
Thistles have been knocked back fairly well. I know I haven't gotten
them all, but in walking through the prairie I see few, and none of
those have seedheads. Of course the vegetation is nearly 6 feet high
in many areas, so I know there are still many out there. I can see the
wisdom of a two to three year control plan, as laid out by Shirley in
her book. I can't effectively tramp through the prairie with Roundup
now. The vegetation is everywhere and it takes lots of time to isolate
a thistle from the prairie plants. So for now, I clip them off at
10-12 inches, which is supposed to keep the plants from sending out new
growth messages to the plant and the rhizomes.
Big Bluestem, Switchgrass, Canada Rye and Sideoats Grama are beginning to develop seedheads. Among the forbs, we were very pleased to discover three blooming Butterfly Milkweeds. There are lots of Cinquefoil, Yarrow, and Black-eyed Susans blooming. Also Rattlesnake Masters, Blue Vervain, Ox-eye and Poppy Mallows are in bloom. We videotaped a prairie tour in mid-June and on July 13th, and we're continuing to photograph new events.
June 20, 2003
I painted more thistles and began to move the prairie files to
Geocities, so as to have plenty of space for photos. Jo-Ann and I shot
about a roll and a half of film. The first Rattlesnake Master plants
are heading out. We also discovered a petite flower we believe to be
Poppy Mallow. A couple of early Ox Eye plants are blooming as well as
a mystery flower which Jo-Ann says looks like a Bachelor Button. It
has a blue blossom. Several other species aare on the verge of
blossoming. I'll post photos of all these when I get the film
developed.
June 19, 2003
I spent two hours painting thistles with Roundup. The second pair of
"heavy duty rubber gloves" was penetrated several times by thistles
after only about 6 hours of use! The first pair lost an entire
fingertip after about 20 hours. I know that I am immune to Roundup. I
plan two sessions tomorrow, as I get off work at noon.
My wonderful wife had the day off and went out to the county road right-of-way and clipped 1000 Canada Thistle plants for me before they could go to seed and be blown directly in the direction of our planting. She stoicly ignored the curious looks of passersby. When I came home from work, I found dead thistles, heaped in a wheelbarrow. A great present! About 30 minutes later, our neighbor down the road came by with his brush mower and tractor, mowing the entire right-of-way! I owe Jo-Ann big-time now!
Presently blooming are lots of cinquefoil and yarrow and a small amount of prairie phlox. The large-flowered penstemons are nearly done with their bloom, as are the spiderworts.
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