Tom's Blog

Wednesday, October 7, 2015

Another way to eradicate Canada goldenrod

I have posted on Canada goldenrod eradication in the past.  My method was a leaf spritz with a low-volume high-concentration of Garlon 4 herbicide diluted in bark oil. [One part Garlon 4 and four parts bark oil.] A few leaves in the upper part of the plant are given a quick spray. This works well, but has the disadvantage that a small amount of herbicide mist might fall on "good" nearby plants.

Two-inch wide foam paint stick
Kathie has developed a modified procedure that permits better control of the herbicide. She uses a foam paint stick soaked with herbicide. Instead of spraying the leaves, she makes a gentle 6 to 10 inch "swipe" up the stem somewhere about waist high. To be certain that no stems are missed, she bends over the top of each stem as it is treated. She carries a small spray bottle to reload the foam from time to time.

The foam sticks are available at any hardware or paint store, in various sizes. A two-inch stick is ideal for this work.\

A Canada goldenrod clone treated about two weeks earlier. The kill rate is about 99%.
Note that there is no peripheral kill on nearby
Desmodium glutinosum plants.
The ideal time to treat Canada goldenrod is from early August through early September, when the plants are in flower. At that time, the plants are large enough to find easily, no stooping is involved, and there is still time enough to return and treat any plants that were missed.

Multi-year studies with the leaf spritz method showed that it was possible to completely eradicate a clone. We anticipate the present modification will be equally effective.

Friday, October 2, 2015

Prairie plants on rock outcrops

In the Driftless Area there are many rock outcrops on which plants appear to be "struggling" for survival. If such an area is fairly large it might be called a "barren" or "bald", depending on its location.

The plants that are growing on rock outcrops are sometimes called "disturbance species", because they may also grow in areas that have suffered considerable human interference.

At Pleasant Valley Conservancy we have several rock outcrop areas, and they are never devoid of plants, despite the thin, almost nonexistent soil. The area that we call the East Overlook is the largest rock outcrop, and is an interesting area to visit. (The Mid Savanna Trail passes below and around the outcrop, continuing onto the Saddle and South Firebreak.)

When we first started restoration work, the East Overlook was heavily colonized with buckthorn, reasonable since this calciphile does well in dolomitic habitats. Years of work have eradicated the buckthorn, and now the site has only native species.

In the spring, small populations of pasque flower and prairie smoke are present. Later columbine can be seen, followed by hairbell and whorled milkweed.

A survey I made yesterday was interesting because there was a large population of hoary vervain (Verbena stricta). Kathie and I counted over 50 stems of this species in an area of about 10 X 20 feet.This beautiful plant is a classic example of a "disturbance species", since it is often found in areas highly disturbed by humans. The best population we have found was on an abandoned commercial site at the corner of County I and County V, just off Interstate 90/94. There was still lots of concrete remaining, and around the edges in the thin soil was a huge population of V. stricta. (Some people might ignore such a species, but it is a true prairie species and not highly invasive, since it probably cannot compete with the "nondisturbance" species.)

Verbena stricta shoots growing out of the very thin soil surrounding the bedrock of the East Overlook

V. stricta in a prairie. It usually thrives best at the edge,
perhaps adjacent to a path.
 Yesterday Kathie and I did a species list for this small rock outcrop. In addition hoary vervain, we found big blue stem, side oats, little blue stem, prairie dropseed, hairbell, whorled milkweed, Kuhnia, Carex eburnii, cream gentian, silky rye, and woodland brome. Also present was a single large eastern red cedar (carefully protected from fire) and several bur oak grubs. Thankfully, there was no buckthorn!

Anyone interested in rock outcrop communities would be advised to access the valuable book edited by Roger C. Anderson, James S. Fralish, and Jerry M. Baskin, 1999. "Savannas, Barrens, and Rock Outcrop Communities of North America." Cambridge University Press. It has 36 chapters that cover the whole of North America, from southern Florida to subarctic Canada. Although I bought this book because of its extensive treatment of North America savannas, I found the chapters on barrens and rock outcrops also interesting. If you are a "plant" person and do much travelling in North America, this is an excellent book to take along. Here are few examples: New Jersey Pine Barrens, Serpentine Rock barrens of Eastern and Western North America, Granite Outcrops of Southeastern  U.S.,  the Cliff Ecosystem of the Niagara Escarpment, Alvars of the Great Lakes Region, Southern Ontario Granite Barrens.

One of the areas Kathie and I visited was Mount Arabia, a site in the southeastern Piedmont region of DeKalb County, Georgia, where there was a large granite outcrop that had tiny islands of soil where primarily endemic species grew. Because of its endemic plants, this area has been protected in a state park.

Saturday, September 26, 2015

Success with sumac eradication

Those following these posts are aware that we have been working hard to completely eliminate sumac from the natural areas Kathie and I manage. Some of the details can be found on earlier blog posts.

Sumac eradication:
Sumac biology and control:

A Search on Tom's Blog will lead to further posts on this topic.

The sumacs at Black Earth Rettenmund Prairie have been a special target of these efforts because it is a high-quality site that had lots of sumac, and its small size makes it convenient to canvas. Our work there began seriously in 2009, at which time there were several areas with large amounts of sumac. Detailed surveys using GPS were made in 2010 and 2011, as shown on the map.

GIS map of the 2010 (red dots) and 2011 (yellow circles) sumac surveys.
The red polygons show the presence of unusually large clones.
#8 is the Narrows and #7 is the Wide Narrows
(near where the photo below was taken).
Beginning in 2010 crews worked through the prairie, mainly in the late fall when the sumac "red" made location easy, and basal barked (with 20% Garlon 4 in bark oil) every stem found. To keep track of the work, the top of each stem was broken to indicate that it had been treated. Several large clones were dealt with separately, as described in the links cited above.

By 2012 we were starting to get on top of the problem, and by 2014 eradication was almost complete.

Yesterday I made a survey of the Saddle and Wide Narrows areas, where large clones had been present. Happily, I found practically no sumac. The photo here shows a small single sumac stem that was buried within the prairie grass and forbs.

Because the intense sumac red has not developed completely in these small plants, a crew will be deployed for a mid-October follow-up survey. The members of that crew will be equipped with spray bottles of Garlon 4, and each sumac plant found will be basal barked.

The photo below shows what one formerly sumac area looks at the present time.

View across the Wide Narrows looking north (photo taken 9-25-2015). In 2010 there was a large sumac clone here.
In June 2015 this area had a large population of wood lilies and in August there was blazing star.

Saturday, September 19, 2015

Swamp thistle: an attractive wetland plant

We have always had swamp thistle (Cirsium muticum) in our wetland, but this year it is particularly prolific in the part of the wetland we burned this April.

The C value of swamp thistle is a relatively high number of 8 (in Michigan it is 10!).

Occasionally we have a few swamp thistle plants in our wet mesic prairies (Crane and Valley), but it is most prolific in the real marsh areas where the water table is close to the surface.

Swamp thistle is native to Pleasant Valley Conservancy and thrives without any help from us. However, we do collect seeds for planting in other parts of the wetland, and are happy if it spreads into areas where we have not seen it before.

In an earlier blog post this year I discussed the use of the hemiparasite lousewort to promote wetland plants. Swamp thistle was one of those that benefited, but my impression is that burning is even more important for this species. 

Like our most common native thistle (old field thistle; C. discolor), swamp thistle is a biennial. It grows from seed its first year as a rosette. Like other biennials in northern climates, it probably requires a cold period to induce flowering. 

This is a beautiful plant with rich purple-colored flowers. It is not surprising that the insects love it!

Friday, September 18, 2015

Milkweed bugs are now thriving

Milkweed bugs feeding on a
common milkweed pod
The milkweed bug (Oncopeltus fasciatus) is specialized for feeding on milkweeds. The principal food of this bug is the milkweed seed, although the nymphs will feed on the leaves and stems. Milkweed plants contain a series of toxic chemicals called cardiac glycosides. Although these glycosides are generally toxic to insects, the milkweed bugs are not affected. Further, the toxins give the bug a bad taste, which helps keep them safe. It is thought that the coloration of the milkweed bug is a signal to birds or other predators to keep away.

The milkweed bug grows well on Asclepias seeds, but grows poorly on seeds of other kinds of plants. In nature the bug is only found breeding on milkweeds of a variety of species. Because of its preference for milkweed seeds, it synchronizes its life cycle with milkweed pod formation. The female only lays eggs at a site where the milkweed pod density is the highest. 

Milkweed bugs on pods of
whorled milkweed
(A. verticillata)
The insect is able to insert its proboscis through the pod wall and suck out the nutrient-rich materials from the seeds.  

Because of its preferential attack on milkweed pods, the milkweed bug is a potential threat to the milkweed population. However, rarely does one find milkweed bugs in such large abundance that the milkweed population may be seriously affected. However, I once saw a nice patch of the Endangered purple milkweed destroyed by a milkweed bug infestation.

See this link for further milkweed buginformation.

Wednesday, September 16, 2015

2015 survey of purple milkweed growth and pod formation at Pleasant Valley Conservancy

Purple milkweed is one of our signature plants at Pleasant Valley Conservancy, and Kathie and I have been monitoring it since 1999. Originally, only a single purple milkweed patch arose in Unit 12B, which was the first oak savanna area restored. The photo here was taken at that first site.

As savanna restoration proceeded, other purple milkweed patches appeared spontaneously. Indeed, even today new patches appear spontaneously, years after the major clearing work involved in savanna restoration was completed. (A nice new population appeared in the bur oak savanna of Unit 11A just this year.)

By our present count, we have 20 patches that have arisen spontaneously and each patch has been permanently marked. Some of these patches have continued to appear every year but some have arisen for a few years and then have disappeared. In some cases, patches that have disappeared have reappeared again in subsequent years, only to have disappeared again.

In addition to patches that have arisen spontaneously, we have also been able to raise plants from seed and have transplanted them to the Conservancy. These transplants have also been permanently marked. Fifteen of these transplants have flowered and survived for many years, although some have flourished for a few years and then disappeared.

The reasons for this wide variability in growth from year to year are unclear, but may partly explain the rarity of this species and why it is listed as Endangered.

In 2015 we had 18 separate locations where purple milkweed plants flowered. At many of these sites, there were multiple flowers, often three umbels per stem. One patch had 15 stems, and a total of 18 umbels.

About half of these 2015 patches were spontaneous, the rest were from transplants.

As a group, pod formation in milkweeds is highly variable. Pod formation apparently only occurs if cross pollination occurs. Thus, pollination will not be successful if a pollinator (e.g. bumble bee) moves from one umbel to another on the same plant. Given the widely spaced distribution of patches at PVC, it is not surprising that pod formation is low. This year only two plants (both spontaneous) formed mature pods. One plant formed 4 pods and the other 2. 

Details of the first 10 years of our study, with photos, can be found in the following paper.

Wednesday, September 9, 2015

Tagging migrating Monarch butterflies

The Monarch butterfly (Danaus plexippus) is unique because of its long-range seasonal migration. The late-summer eastern North America populations migrate alll the way to central Mexico, where they overwinter. In the spring, the same individuals migrate to Texas or Oklahoma where they mate and produce a second generation, which migrates further north. Third and fourth generations may continue the northern migration before the butterflies finally settle for the rest of the summer in breeding grounds such as southern Wisconsin. 

Monarchs lay their eggs exclusively on milkweeds. We have lots of milkweeds at Pleasant Valley Conservancy, and hence lots of Monarchs.

In early September, the mature individuals prepare for the long southern migration. Although the return trip is long and arduous, significant numbers of individuals do complete the journey, where they overwinter in the Mariposa Monarca Biosphere Reserve (Michoacan province). 

Tracking this migration as part of a widespread butterfly conservation movement is an organization based in Lawrence, Kansas called Monarch Watch. Madison Audubon Society is cooperating with Monarch Watch and managing the tagging of Monarch butterflies in our area. The local headquarters for the tagging operation is at the MAS Goose Pond Sanctuary (Mark and Sue Martin). 

This is the second year that Kathie and Pleasant Valley Conservancy have been cooperating with MAS and Monarch Watch. Although catching and tagging Monarchs is not easy, today Kathie caught and tagged four Monarchs at PVC, three in the area of the East Basin and Ridge Prairie, and the fourth at the Pocket Prairie. All were successfully tagged and released!

The tags are small light-weight paper disks that contain a harmless adhesive.
After catching the butterfly in a net (the hardest part of the operation),
one of the numbered tags is picked  up with a toothpick.

Placing the tag on the butterfly's wing.
At this stage the sex of the butterfly is noted for the record.

The probability of a tagged butterfly reaching the Mariposa reserve is low, and the probability is even lower that someone might spot the tag and report it to Monarch Watch. Even so, at least one Monarch tagged at Goose Pond Sanctuary has been reported from Mexico. A $5 reward is given to anyone reporting a tagged butterfly.

Releasing the tagged butterfly.
The tagging operation does not harm the butterfly.