Tom's Blog

Friday, May 27, 2016

Eradication of invasive plants (2): perennials

This is the second of two posts on invasive plant control. Last week’s dealt with biennials.

The table at the end provides an overview of key perennial weeds and a summary of control methods.

Perennial weeds may start as seeds or from underground roots or rhizomes. The life span of perennials varies widely. Some last only a few years whereas others may last indefinitely. Because of their root systems, it is unlikely that a perennial will be eradicated by digging the plant up. Thus, permanent control of perennials almost always requires the use of an herbicide.

Eradication of most perennial weeds requires great effort and extended time periods, generally over a multi-year period. Neither fire nor mowing will eradicate any perennial weed, although these procedures may find good use along with herbicide.

Most of the weeds in the table are dicots and hence susceptible to broad-leaf-specific herbicides such as 2,4-D, clopyralid (Transline), metsulfuron methyl (Escort), and triclopyr (Garlon). The one monocot in the table, reed canary grass, is controlled by a grass-specific herbicide such as clethodim (Intensity). Under certain conditions it may also be possible to use a nonspecific herbicide for these weeds such as glyphosate (Roundup). Details on the manner of use are given in the herbicide label specifications.

In the rest of this post, I give our own experience for successful eradication.

Spotted knapweed This is more of a problem in dry, sandy areas. However, when our gravel road was redone about 6 years ago, the contractor brought in gravel that was contaminated with seeds of this species. Each year for the next few years we waited until it was in flower and then spot-sprayed each flowering plant along the whole roadside with aqueous Garlon 3A as a foliar spray. This was effective and by year 4 this species had been eradicated.

Spotted knapweed growing in contaminated gravel brought in for road repair


Canada thistle This is one of the few weeds that is listed by the State of Wisconsin as a noxious weed. As far as I know, it is the only thistle species that is a perennial. It forms an extensive underground rhizome system. However, it does not compete well with prairie plants so that it is often only a problem in the early years of a prairie restoration. In the early years of our restoration work, small or larger patches of this weed popped up in planted prairies or in open savannas. Some of the smaller (i.e. less than 6 feet) patches could be controlled just by mowing consecutively for several years at the time of flowering. Larger patches were controlled by mowing at flowering time and returning later to spray the resprouts with glyphosate or triclopyr. We haven’t seen Canada thistle at PVC for at least six years.

Crown vetch This is a very aggressive plant which is very difficult to control. It has an extensive rhizome system and the seeds, like many other legumes, are very long-lived in the soil. The key is to not let it get started. US Highway 18/151 is heavily infested (probably planted when the road was rebuilt) and it is now moving off onto some of the nearby county highways. I watched one nice prairie remnant over which I had no control get taken over by crown vetch over a period of ten years, despite frequent burns. At PVC we had a single patch of crown vetch pop up on the lower part of our south-facing slope. I have no idea where it came from. It is easy to spot when flowering, and I sprayed it immediately with Garlon 3A. It quickly died and has so far not returned.

Leafy spurge This is another plant that is troublesome along roadsides and is a potentially serious invader of natural areas. It has a deep tenacious root system and spreads rhizomatously. Fortunately, we have never had to deal with this nasty plant, although we see it spreading along US 14 between Middleton and Cross Plains. Currently, the recommended herbicide for leafy spurge is imazapic (Plateau), spraying twice in the growing season, late spring (before seeding) and in the fall just before a killing frost.

Birds-foot trefoil This legume was once planted extensively agriculturally and because of its long seed life (as bad as sweet clover!) it can be a problem in prairies that are being established on former cropped fields. It is not rhizomatous but forms a deep tap root from which stems arise that spread out along the top of the soil. Because of its low-growing character, it is hard to see until it flowers. We have been dealing with this in Toby’s, the Pocket, and Ridge Prairies since they were first established. Our procedure is to find the center of the plant and give it one or two brief spritzes with 20% Garlon 4 in oil. The plant should be dead within a week. Details of its ecology and control can be found in my earlier post.

Reed canary grass (in upland sites) Reed canary grass is a major problem in wetland systems but does occur occasionally in upland sites. We have been dealing with this in some of our savannas for at least 15 years. It generally occurs as relatively small patches which can best be found at the time of flowering. Spray each patch with Intensity. If that herbicide is not available an alternative is to cut with a hand clippers each plant about six inches to a foot above the base, tie the stems together in a bundle, and use a spray bottle to treat the cut stems with 50% Roundup. This is a fairly time consuming procedure but is effective.

Motherwort This perennial is primarily a problem in heavily disturbed areas. It appears fairly early in the spring, before most native species are still dormant, and should be sprayed with foliar glyphosate or a broad-leaf specific herbicide.

Latin name
Common name
Growth
Severity (1)
Control methods
Centaurea maculosa
Spotted knapweed
Biennial or short-lived Perennial
Especially dry prairies and sandy habitats; more serious in western states; don't let it get started!
Spring and fall spray with broad-leaf-active herbicide
Cirsium arvense
Canada thistle
Perennial
Moderate; generally outcompeted in well established prairies; don't let it get started!
Spring spray with broad-leaf-active herbicide; summer mow; fall spray with broad-leaf-active herbicide
Coronilla varia
Crown vetch
Perennial
Now a potentially serious invader of prairies and savannas; don't let it get started!
Spring and fall spray with broad-leaf-active herbicide
Euphorbia esula
Leafy spurge
Perennial
Now a potentially serious invader of prairies and savannas; don't let it get started!
Spring and fall spray with broad-leaf-active herbicide
Leonurus cardiaca
Motherwort
Perennial
Low
Broad-leaf herbicide
Lotus corniculatus
Birds-foot trefoil
Perennial
Moderate
Broad-leaf herbicide; longlife seed bank; difficult to eradicate
Lythrum salicaria
Purple loosestrife
Perennial
Low
spray with broad-leaf-active herbicide when found
Phalaris arundinacea
Reed canary grass
Perennial
Low
Spring and fall spray;summer cut followed by spray of cut stems
Trifolium repens
White clover
Perennial
Low; outcompeted in established prairies (except along edges)
Spring spray with broad-leaf-active herbicide
(1)    Severity refers to prairies and savannas only. Wetland habitats will be different.

Saturday, May 21, 2016

First "official" Monarch sighting in Wisconsin at Pleasant Valley Conservancy

According to Prof. David Hogg, Monarch specialist at UW-Madison, the first "official" 2016 sighting of Monarch butterflies in Wisconsin was made Thursday May 19 at Pleasant Valley Conservancy.

Here is the report: The first “official” 2016 sighting of Monarch butterflies in Wisconsin was made yesterday at Pleasant Valley Conservancy, specifically in the oak savanna habitat on the south facing hillside.  I’ve attached photos of the adult (female) and one of the eggs she deposited.  We (Cameron Fullerton and me) watched her flit from milkweed to milkweed, and it appeared that she laid eggs on a dozen or more stems.  We examined a number of milkweeds after she left, attempting to target those she had visited (not easy to do with the large number of milkweed stems in the patch) and were able to find four of her eggs on stems ranging from 4 to 9 inches tall.

The sighting was recorded with the Southern Wisconsin Butterfly Association  <https://wisconsinbutterflies.org/butterfly/sightings>.

Monarch season has begun!
Monarch butterfly on shoot of common milkweed (Asclepias syriaca). David Hogg photo

Monarch egg on milkweed leaf. David Hogg photo

Those interested in helping further the Monarchs at Pleasant Valley Conservancy are invited to be volunteers Sunday May 22, 2016 from 10 AM until 4 PM (or any fraction thereof). We will be planting swamp milkweed and meadow blazing star "plugs", favorite Monarch plants.

Friday, May 20, 2016

Monarch butterfly project at Pleasant Valley Conservancy: volunteers needed Sunday May 22, 2016!

Monarch butterflies need all the help they can get! Pleasant Valley Conservancy (PVC) has lots of Monarch habitat, but more is  needed to replenish the diminishing populations of these important and attractive migrating insects.

At PVC, thanks to Kathie's efforts, we have been awarded a grant from the U.S. Fish & Wildlife Service to encourage Monarchs. Among other things, this grant has supported the purchase of seedlings of two important Monarch plants: swamp milkweed (Asclepias incarnata) and meadow blazing star (Liatris ligulostylis).

Volunteer help is needed to plant these seedlings.

Meet at the PVC Barn at 4609 Pleasant Valley Road. Hours are from 10 AM until 4 PM. Bring your lunch. Drinks and desert will be provided.

For information, call Kathie at 608-238-5050.


Monday, May 16, 2016

Invasive plants (weeds) eradication (1): biennials

This is the first of two posts on weed control. It deals with biennial plants. The second post on perennials will be made next week. The table at the end of this post provides a survey of all the invasive plants that are potentially a problem in the Upper Midwest area.

It seems unfair that as soon as nice plants are blooming in our prairies and savannas that invasive plants are also thriving. Unfortunately, we can’t let the invaders get ahead of us!

Biennial plants grow from seed their first year but do not flower. The cold period during overwintering induces flower bud formation and the second year they send up flower stalks and set seed.

Whether biennials are a problem in restoration ecology depends to a great extent on whether a seed bank exists and how long their seeds remain alive in the soil. Although there is little information on seed bank longevity, for many purposes it may prove best to assume that the life in the seed bank is extended. Thus, it makes sense to always assume that there will be an overwintering seed bank and that new plants will be appearing the following growing season. If they don’t show up, consider that a bonus!

The control cycle for a biennial like garlic mustard runs something like this:

First-year plants
  1. First-year plants at the seedling stage may be visible sometime in April-May. While they are still at the cotyledon stage they can be killed by fire. This is best accomplished with a propane torch carried on a backpack.
  2. First-year plants past the cotyledon stage are generally mixed in with native species and will be hard to find until late in the summer/early fall. They remain green long into the fall, making them visible when native species have senesced and turned brown (late November or anytime in December before snowfall). Since there are no green native plants at this time, spraying with glyphosate is preferred since this herbicide has no soil residual. The plants will not show any response to the herbicide, but will not come up the following spring. This is a very effective time to deal with first-year plants since all first-year plants controlled in the fall will not have to be dealt with the following year.
Second-year plants


  1. Most effort on garlic mustard focuses on second-year plants. Spray new growth in early spring as soon as the plants are large enough to find, using a broad-leaf active herbicide.
  2. The earlier spraying can be initiated, the better.
  3. Return at weekly intervals, or more often if good growing conditions exist (depending on the weather).
  4. Flowering plants that were missed, or flowering plants discovered too late to spray should be mowed with a brush cutter or hand-pulled before they set seed. Arguments exist about whether pulled plants will go on to make viable seeds if they are just laid on the ground. Most cautious people assume that flowering plants will go on to set seed and thus bag them for disposal in a land fill.
  5. Once plants start to form seeds they should definitely be bagged.
  6. The area should be canvased at weekly intervals until the end of June, removing all flowering plants.
  7. It is vital to prevent any plants from making and dropping viable seeds.
  8. Experience has shown that eradication of garlic mustard requires many years, but it can be done.
Wild parsnip


Wild parsnip is generally easier to eradicate than garlic mustard. The same techniques are used, although the timing is different.

Sweet clover
            Sweet clover is probably the most expensive weed that we deal with in prairie restoration work. In contrast to garlic mustard, the control cost per person hour per acre is quite high, and most infested areas are almost impossible to eradicate. It is found primarily in prairie remnants, as a legacy of their former use as pastures. The seed bank can remain alive for many years, and seed germination is stimulated by fire. I discuss the history of sweet clover in the UpperMidwest in this post:


First-year plants
1.     Very difficult to find early in the growing season, as they are small and delicate.
2.     In late fall, after native plants have senesced, they will still be green and can be sprayed with glyphosate. This is very effective, but areas sprayed must be monitored in subsequent years.
Second-year plants
1.     Begin control as soon as significant patches are found, usually mid-June or early July in the Upper Midwest. From then on, sweet clover will probably continue to appear throughout the summer.
2.     Scattered plants should be hand-pulled or dug using a shovel (a Parsnip Predator is ideal). The whole site should be canvassed biweekly until fall.
3.     Sweet clover is often found in large patches, even up to several acres, making hand pulling not really an option. Wait until all plants are in flower and mow, either with a brush cutter or a tractor. Timing of mowing is critical. If too early, plant stubs can resprout and flower. If too late, the cut flowers lying on the ground can set seed.
4.     Return to mowed areas within a week or two and hand pull those plants that were missed.
5.     Sweet clover forms a long tap root, and when hand-pulling, it is important to get the whole root. There are dormant buds at the base of the stem which will start growing if the stem is broken without getting the root.
6.     A strategy that has worked well is to pass through each unit at least once a week, pulling all visible plants. In seriously infested areas, monitoring weekly from early June until the end of July, then returning in September when there is often a resurgence of smaller flowering plants. Never allow seed formation to occur.
7.     Once sweet clover control has started, it must be continued annually, because if any sweet clover plants are left to set seed, the initial control efforts will have been wasted.

Japanese hedge parsley
About 20 years ago this was considered a newly emerging noxious weed. Unfortunately, it is now well established, at least in the southern part of the Upper Midwest. Hedge parsley is probably more difficult to eradicate than garlic mustard, but is less noxious and hence is often overlooked.


Hand-pulling is the preferred control method although spraying with a broad-leaf-specific herbicide will also work.

The severity given in the table below is for prairies and savannas. Wetlands are different!

Common name
Growth
Severity]
Control methods
Alliaria petiolata
Garlic mustard
Biennial
High; mainly in shadier areas
Spring and fall spray; hand pull; don't let it get started!; eradication takes years
Arctium minus
Common burdock
Biennial
Low
Spring spray with broad-leaf-active herbicide
Cirsium vulgare
Bull thistle
Biennial
Low
Hand pull, dig or spray with broad-leaf-active herbicide
Daucus carota
Queen Annes lace
Biennial
Moderate; generally outcompeted in well established prairies
Hand pull, mow, or spray with broad-leaf-active herbicide
Dipsacus laciniatus
Cut-leaved teasel
Biennial
Low
Hand pull, mow, or spray with broad-leaf-active herbicide
Dipsacus sylvestris
Common teasel
Biennial
Low
Hand pull, mow, or spray with broad-leaf-active herbicide
Hesperis matronalis
Dames rocket
Biennial
Low
Hand pull, mow, or spray with broad-leaf-active herbicide
Melilotus alba
White sweet clover
Biennial
High
Hand pull, mow, or spray with broad-leaf-active herbicide first-year plants in fall; long-life seed bank; eradication very difficult
Melilotus officinalis
Yellow sweet clover
Biennial
High
Hand pull, mow, or spray with broad-leaf-active herbicide first-year plants in fall; long-life seed bank; eradication very difficult
Pastinaca sativa
Wild parsnip
Biennial
High
Hand pull, mow, or spray with broad-leaf-active herbicide; can be eradicated with hard work
Verbascum thapsus
Mullein
Biennial
Moderate; establishes on bare ground; generally outcompeted in well established prairies
Hand dig or pull; late fall spray with broad-leaf-active herbicide or glyphosate
Torilis japonica
Japanese hedge parsley
Biennial or winter annual
Moderate; mainly in shaded areas
Hand pull, mow, or spray with broad-leaf-active herbicide; difficult to eradicate
Centaurea maculosa
Spotted knapweed
Biennial or short-lived Perennial
Especially dry prairies and sandy habitats; more serious in western states; don't let it get started!
Spring and fall spray with broad-leaf-active herbicide
Cirsium arvense
Canada thistle
Perennial
Moderate; generally outcompeted in well established prairies; don't let it get started!
Spring spray with broad-leaf-active herbicide; summer mow; fall spray with broad-leaf-active herbicide
Coronilla varia
Crown vetch
Perennial
Now a potentially serious invader of prairies and savannas; don't let it get started!
Spring and fall spray with broad-leaf-active herbicide
Euphorbia esula
Leafy spurge
Perennial
Now a potentially serious invader of prairies and savannas; don't let it get started!
Spring and fall spray with broad-leaf-active herbicide
Leonurus cardiaca
Motherwort
Perennial
Low
Broad-leaf herbicide
Lotus corniculatus
Birds-foot trefoil
Perennial
Moderate
Broad-leaf herbicide; longlife seed bank; difficult to eradicate
Lythrum salicaria
Purple loosestrife
Perennial
Low
spray with broad-leaf-active herbicide when found
Phalaris arundinacea
Reed canary grass
Perennial
Low
Spring and fall spray;summer cut followed by spray of cut stems
Trifolium repens
White clover
Perennial
Low; outcompeted in established prairies (except along edges)
Spring spray with broad-leaf-active herbicide





Wednesday, May 11, 2016

Stephen Pyne webinar on Fire History and Ecology

The Joint Fire Science Program of the U.S. Government is an important resource for all those involved in prescribed fire. Each region of the country has a fire science organization that fosters prescribed fire in that region. These consortiums are funded by the key Federal agencies that are involved in prescribed fire: Forest Service, Fish & Wildlife Service, BLM, National Park Service, Bureau of Indian Affairs, and the U.S. Geological Service.



Wisconsin is actually in two separate consortiums, Lake States and Tallgrass Prairie and Oak Savanna. But I have found that the Oak Woodlands and South Fire Exchange often have information of importance to us Midwesterners.

Recently the Southern Fire Exchange presented an important webinar by acclaimed fire historian Stephen Pyne which was very worth watching. It has now been archived and is available as a YouTube file

For background on Stephen Pyne (among other things, he is a MacArthur Fellow), and a list of his numerous books on fire, access this Wikipedia page.

I strongly recommend this webinar for anyone who is interested in fire ecology.

All of the fire science exchanges have websites which can be accessed via a standard internet search. Their past webinars are generally archived and can be accessed via their websites. Also, you can sign up for email notifications from any of the programs.

Sunday, May 1, 2016

Potential serious impact of a new American Transmission Company (ATC) power line on Pleasant Valley Conservancy

ATC, the American Transmission Company, which operates high-voltage transmission lines from giant towers in Wisconsin, is in the process of deciding a route between a major site called the Cardinal Substation (off US 14 on Willow Lane, 1.6 miles mile west of Pleasant View Road in Middleton) and a proposed new substation south of Montfort on the edge of Iowa County.

There are two possible routes, both of which go west from the Cardinal Substation to Cross Plains. From there, one goes south on County P to US 18/151 and then west along this "super" highway to Iowa County.

The second route charges due west across the Town of Cross Plains and the Town of Vermont, and goes directly across Pleasant Valley Conservancy State Natural Area!
ATC-provided map showing the preliminary corridors of the power line across southwestern Wisconsin

The ATC map carefully shows in green what they call "environmentally sensitive lands", but is seemingly unaware of PVC. In fact, only state-owned land is shown in green. The fact that PVC is a Dedicated State Natural Area has been missed completely. (Not that this would necessarily stop them from choosing this route!)

Using GIS, I scanned the ATC map of the route through the Town of Vermont, georeferenced it, and overlaid it on my map of PVC. As the map here shows, PVC is completely inside the power line corridor.

Map showing the location of the "corridor" that crosses over the top of Pleasant Valley Conservancy.
The map provided by ATC was scanned and georeferenced so that its boundaries could be mapped.
Those mapped boundaries are shown crossing north and south of PVC.
Where would the giant towers be?
Naturally, we will be providing ATC with all the information we have on PVC, including maps, species lists, and boundaries. Most especially we will be pointing out the large number of ancient bur oaks that are present, some having their origins in colonial times.

I'll have more to say about this power line situation later. Naturally, Kathie and I will be attending the public meeting to be held Wednesday May 18, 2016 from 4-7 PM at Deer Valley Lodge, 401 Industrial Drive, Barneveld 53507. Hopefully, people from TPE and others interested in preserving ecologically sensitive lands will also be attending.

Friday, April 29, 2016

May is a Good Time for Invasive Shrub Control in Prairies and Savannas

At Black Earth Rettenmund Prairie we have three burn units, and burn each on a rotation of two out of each three years. Thus, each year we have one unburned unit and two burned ones. Each year a different unit is left unburned.

The unburned unit is the one in which we do invasive shrub control.

Invasive shrub control focuses on the unit which is in its “off” burn year. Invasive brush in that unit is easy to find, because the above-ground buds are alive and leaf out. They are thus easy to find during a stroll through the unit and are easy to kill because they are not very large.

How to kill the invasive shrubs?

  • If it is a single isolated plant: cut each stem of that plant with a hand clippers and treat the cut stem with herbicide (Garlon 4 at 20% concentration in bark oil)
  • Or: don’t cut but treat the stem near the base (basal bark) with Garlon
  • If it is a large clone such as one often finds with aspen, hazel, buckthorn, or sumac: cut the whole clone with a power brushcutter and treat each cut stem with Garlon
  • For isolated stems of a straight-growing plant like aspen: swipe up from the base of each stem with a sponge stick loaded with Garlon in oil



This “one-out-of-three” approach makes a lot of sense, because you only have to do invasive shrubs in one-third of the prairie.

Hopefully, there are no invasive shrubs in the two units that were burned this spring. However, any straggling invasive shrubs that might be present would have been top-killed so they do not leaf out.

However, if there are still invasive shrubs in the units that have been burned, they can be dealt with later in the summer when they have resprouted and are tall enough to find. Or even better, wait until late fall, after all the native vegetation has senesced, and the invasive shrubs can be found more easily. Then use one of the treatment methods listed above.

Note that invasive brush can also be worked on all winter, even when there are no leaves. Again, any of the methods listed above can be used.


An important point: you can’t eradicate invasive brush in a single year. It is essential to return year after year, since there will be resprouts or root suckers or new seedlings which will turn into shrubs. Keep at it.

Black Earth Rettenmund Prairie looking south across the Saddle Unit from the North Unit. The brown patch in the background is the unburned South Unit, where brush control will be carried out.