Paying Attention to the Season During Restoration Work

Paying Attention to the Season During Restoration Work

Paying Attention to the Season During Restoration Work

By Jim Rogala

October 3, 2023

Prairie restoration land managers, whether landowners or those working on public or protected lands, typically have long lists of management needs. I’m no exception. My list contains many lifetimes of work I could do, so I prioritize tasks and tackle urgent needs first. These are typically long-range plans that span years and even decades. However, there is another component to selecting which task to work on at a shorter time scale: seasons of the year. 

I’ve always had this seasonal aspect of restoration in my mind, but that is not very conducive to sharing it with others. As a past member of The Prairie Enthusiasts Education Committee, I proposed doing a simple guide to formalize the seasonal aspect of prairie restoration.  

There are many factors that contribute to selecting which time of the year someone might do a specific task. Some examples are: 

Plant Physiology

The translocation of materials in plants can vary drastically by season, not only in the rate of movement but also the dominance of some movement over others across seasons. Also, there are times when most of the energy in a plant is above ground, and other times it is below ground.  

Herbicide Efficacy

Herbicides have temperature ranges that are best suited for their effectiveness 

Preparation for Upcoming Tasks

Some tasks are simply preparing for other tasks. If the work is not done to meet the requirements of performing an upcoming task, then you may have to delay doing something for a year. 

Snow Cover

The presence of snow is a good time for some tasks and not good for others. 

Keeping such factors as these in mind, it becomes obvious that performing some restoration work is best done in a particular season. Some examples are: 

        • When cutting and treating trees and brush, consider the optimum season to best translocate the herbicide to the location of action. If it is too cold or too hot, and the translocation is slow. Oil-based herbicides also volatilize at high temperatures. 
        • For non-herbicide methods such as repeated cutting, summer is the preferred time because most of the energy stores are above ground. For clonal species, it is critical to not cut in fall or winter if you are not applying herbicide, as this will promote resprouting from nodes. 
        • Mowing firebreaks in preparation for a spring burn should be done before winter to minimize dry debris on the break. 
        • Brush pile burning is best done in the winter when there is snow on the ground. 

The work of the Education Committee, with helpful reviews from our Science Advisory Group, yielded a document titled: Quick guide to restoration practices: Timeframes and general methods. We hope those that are doing restoration find the guide informative and useful in planning seasonal activities. And, as you might notice, there are no seasons with nothing to do! 

Quick Guide to Restoration Practices: Timesframes and General Methods

Quick Guide to Restoration Practices: Timesframes and General Methods

Guide to Restoration Practices

Timeframes and General Methods

Story by Jim Rogala

October 3,  2023

The timing of most mechanical and chemical treatments to control unwanted plants is most effectively performed when taking into consideration plant anatomy and physiology, phenology, and the physical conditions of the site. For example, knowing where the cells that translocate materials are located (i.e., anatomy), along with how and when this translocation is occurring (i.e., physiology) are critical. For herbicide treatments, translocation from the point of application to area of action needs to be considered. Many mechanical treatments focus on depleting energy stores and therefore timing to disrupt the translocation is key. There are also weather conditions within seasons to consider, such as rain forecasts prior to herbicide application or hot conditions that slow the translocation process.

Below are some recommendations for seasonal, priority management actions. This information is intended to serve as a starting point for planning the timing of work to have maximum desired impact and not to provide all details related to various methods. Please search for additional information about management techniques as needed.

Fall Tasks

Search for invasives such as honeysuckle and buckthorn that still hold green leaves after others have changed color or fallen.

Cutting and treating woody non-clonal invaders (note exceptions below)

        • Avoid times when things are wet or there is more than 3-4” of snow cover.
        • Do not apply herbicide, especially water-based herbicides, prior to a precipitation event (wait at least 4 hours)
        • Do not use oil-based ester herbicides (e.g., Garlon 4) during the growing season in high-quality remnants if temperature is above 60-65 degrees because of volatilization transfer
        • Follow good practices such as cutting and treating all stems of the plant, apply water-based herbicide immediately after cut and oil-based soon after. Use water-based herbicide in wet areas and use a water-base or oil-base herbicide if above freezing (concentrated Glyphosate mix, 20% active ingredient, works well on species sensitive to glyphosate down to 20 degrees) or oil-based herbicide if below freezing. Many details on herbicide selection and use can be found in currently available resources, especially herbicide labels.

Cutting and treating clonal species such as sumac and aspen

        • Requires that the entire clone be treated in most cases. Consider non-herbicide methods during other seasons (see below).
        • NEVER cut any clonal species without herbicide treatment during fall or winter
        • May need follow-up on some species in the following year

Basal bark spraying

Brush piling after plants have died back

Cutting coniferous trees (late fall to avoid trampling desirable plants during seed production)

Firebreak work (for winter and spring burns). In addition to other break work, mowing grass breaks for spring burns best in fall

Prescribed burning (consider timing of these and if prior management needs to be done first; for more information about prescribed burning, stay tuned for details about our annual conference which includes burn school)

Seed collecting

Seed dispersal

Winter Tasks

(some of these activities are easier and more effective with little or no snow cover)

Brush piling

Brush pile burning when snow is on the ground (add to burning piles to reduce the number of piles)

Cutting and treating woody invaders (note exceptions listed under fall and below; avoid times with extreme low temperatures)

Basal bark spraying

Cutting coniferous trees

Prescribed burning when prairies are snow-free and snow in surrounding woods (consider timing of these and if prior management needs to be done first)

Firebreak work (for winter and spring burns)

Seed dispersal (earlier is better)

Plant plugs while conditions are still moist

Early Spring

Prescribed burning (consider timing of these and if prior management needs to be done first)

Pulling woody species of small size when soil is wet.

Search for invasives with green leaves (e.g., garlic mustard) before others have leafed out. (Although shrubs like honeysuckle and buckthorn can be found at this time, do not cut and treat if the sap is flowing at a high rate).

Flame weed garlic mustard seedlings in May (where leaf litter or grassy fuels are present, do this when conditions are wet).

Pull garlic mustard and dame’s rocket before seeds start to develop.

Seeding can be done in early spring, especially if preparation for seeding includes a burn prior to seeding.

Late Spring

Girdling without herbicide treatment of trees such as aspen (some other species, but not all)

        • Must do all trees for clonal species
        • Do not use this method on black locust.

Seed collecting (disperse after collected for some species)

Summer

Double-cutting clonal woody vegetation, including sumac and young aspen (~July 1 and August 1 for multiple years; no herbicide; not black locust)

Cutting and treating woody invaders (note exceptions listed under fall and below; see comment regarding high temperatures under the “good practices” in the fall section)

Mowing invasive species (consider timing)

Firebreak work (for fall burns)

Foliar spraying (consider timing based on species herbicides)

Root-severing of monocarpic species (e.g., wild parsnip, biennial thistles)

Seed collecting

Dispersal of fresh seed from early flowering species whose seeds ripen early

Assess community health/progress towards restoration goals

Want to have this guide handy when you’re outside? Download the PDF of this guide by clicking HERE.

And, read our other seasonal guide blog post HERE.

Eliminating Buckthorn Without the Use of Herbicide

Eliminating Buckthorn Without the Use of Herbicide

Eliminating Buckthorn Without the Use of Herbicide

Story and Photos by Ron Rigden

October 2, 2023

Typical regrowth of buckthorn

Buckthorn is an invasive shrub that has infested many of the forests and bluff prairies of the Upper Midwest, including Hixon Forest in La Crosse where our Coulee Region Chapter has been working to control it. It is known that cutting buckthorn without treating the stump with an herbicide causes it to resprout. It is not known how frequently or how long buckthorn must be cut before it doesn’t resprout, or if it is even feasible to kill buckthorn by just repeatedly cutting it. Friends of the Blufflands has partnered with our chapter to help answer this question by sectioning off an area in Hixon Forest with heavy growth of relatively small buckthorn plants and cutting parts of that area at different frequencies. We hope to be able to determine the minimal frequency that young buckthorn needs to be cut to eliminate it without the use of herbicide. 

Hypothesis

If young buckthorn is repeatedly cut it will eventually not resprout. The minimal frequency after mid-June until the first hard frost at which this cutting must take place is unknown.

Methods

A 400-square-foot study plot was chosen for its uniformity of buckthorn growth. The buckthorn was about waist to shoulder high with the diameter of stems mostly about half to three-quarter inch or smaller. This area was cut close to the ground on June 16 with a handheld brush cutter. The cut stems were gathered and removed from the area, then a second pass was made with the brush cutter to assure that all the stems were cut. The plot was marked off and divided into four sections, each measuring 10 by 10 feet. These sections go up the slope from bottom to top. The four sections were cut at four different frequencies (every 2 weeks, 4 weeks, 6 weeks, and 8 weeks). A border was also cut around this 400-square-foot plot. The nearby uncut buckthorn was used as a control. Subsequent cuttings were done from that date until the first hard frost, which occurred on October 25, 2022. It is recognized that new seedlings from the seed bank would appear and must be taken into consideration.

 

Area before cutting

Cutting schedule (though the actual cutting took place near these dates due to weather or other factors)

10 x 10 feet sections marked off after cutting

On 6/16/2022 a 15 x 50 feet section on Lookout savanna, well east of an area that had been foliar sprayed the previous year and easily accessible from Savanna Trail in Hixon Forest, was chosen for its uniform growth of common buckthorn. The buckthorn was about waist to shoulder tall with the diameter of stems mostly about 0.5 to 0.75 inch or smaller. There were minimal other woody plants present, such as honeysuckle or oriental bittersweet. This area was cut with a weed wacker with a blade close to the ground, the cut stems were gathered and removed from the area, then a second pass was made with the weed wacker to assure that all the stems were cut. Then four side-by-side 10 x 10 feet areas were staked out within this 15 x 50 foot area. Down the slope and separated from the 15 x 50 area by a 3-4 foot cut buffer, a second 10 x 10 area had all the woody plants removed with the traditional cut and treat method using hand held pruners and 20% triclopyr in bark oil with surfactant and blue dye.

Study Plots Two Weeks Later on 6/30

The cuttings proceeded through the year according to the schedule with the last cutting of sections 1 and 3 taking place on 10/25/22 after which a hard frost occurred. Here are the measurements of growth in the 4 sections on this date:

Section 1
Top 5 averaged 1.5 inches of regrowh

Section 2
Top 5 averaged 2 inches of regrowth.

Section 3
Top 5 averaged 4 inches of regrowth.

Section 4
Top 5 averaged 5 inches of regrowth.

Status through the Winter

Photos taken on June 6, 2023

Section 1

Section 2

Section 3

Section 4

A view of the entire plot looking east

Note that some of the stakes fell over during the winter months. Also note that the green seen in the photos is mostly other plants such as violets, not buckthorn, except in section #4. As seen in the photos, sections 1, 2, and 3 were almost identical with some minimal regrowth of buckthorn. Section 4 had significantly more regrowth both in the number and height of the plants.
 
The separate section that had the buckthorn removed by traditional cut and treat was almost free of buckthorn on 6/6/23 with three plants still present. These were likely either missed or not enough of the herbicide was applied to be effective.
Conclusion:
 
Repeatedly cutting small diameter common buckthorn approximately every 4 to 6 weeks starting in mid-June until the first hard frost can be an effective strategy to eliminate most of the buckthorn and be left with very few stems and a much more easily managed population the next year. In this example that meant cutting the area 3 to 4 times from mid June to late October at 4 to 6 week intervals. Of note, the cuttings were done very close to the ground such that almost no leaves were left on any of the plants that had regrown. This might be difficult to replicate in a larger and rocky area.

If you’re interested in partaking in management research like this, send us a message!

Controlling clonal tree species by double-cutting

Controlling clonal tree species by double-cutting

Controlling Clonal Tree Species By Double-Cutting

By Jim Rogala

Continuing on the theme of herbicide-free control methods, I’ll talk about my experience with double-cutting. Again we look to the anatomy and physiology of the species to be controlled to understand how this works [for those of you that know why double cutting works, or don’t care why it works, you can skip the next three paragraphs]. Clonal species form what looks like many plants when in fact it is a single plant with many stems. These clusters of stems often have larger older stems toward the center and smaller younger stems on the perimeter. No matter what the control method you use (mechanical or chemical), all stems of the clone need to be treated. Cutting off the stems in the winter results in the formation of new stems from adventitious nodes the next spring.  Where there were tens (or hundreds) of stems prior to cutting, you might have hundreds (or thousands) after a winter cutting.

When to Cut

Cutting any plant when most of the energy stored in the roots has been translocated to above ground plant parts is advantageous. For most trees, this translocation occurs throughout the spring and early summer when it is building structures to 1) produce new energy, 2) to add to its size, and 3) for reproduction (leaves, trunk/branches, and flowers/fruit, respectively). After this annual use of energy from the roots is done, the tree begins translocating energy back to the roots at higher percentage. So, to deliver maximum hurt to the tree, cutting before energy starts going back to the roots is a good strategy. This maximum damage also minimizes prolific sprouting from adventitious nodes.

Even with a well-timed cutting, a tree still has enough energy in the roots to produce more above ground structure to assure it lives on. Here’s where the double-cutting comes in. After the first cutting, the tree needs to again use the remaining energy in the roots to build all new structures for the purpose of gaining energy (reproduction is put on hold under these stressful times). Similar to the first cutting, this second cutting is timed to coincide with maximum translocation of energy from the roots, but again not waiting past the period where a lot of energy is translocated to the roots.

I read about doubled-cutting years ago and have used it quite a bit. I generally follow the July 1 and August 1 timing for cutting but have varied it a little depending on growth in a given year (e.g., first cutting for sumac is usually after flowering). I’ve done the “cutting” with a variety of methods. I’ve used a mower if clones are large, where mowing is feasible, and the clone is not in a high-quality prairie. The point related to high quality prairie is that multiple years of repeated mowing can have negative effects on some desired species. I’ve found mowing to not be as effective, as it reduces shading of resprouts because everything gets cut. I’ve used a handheld brushcutter in native prairie areas, cutting each stem individually. It’s not as quick as mowing, but less damaging to other prairie species and better than using hand loppers to cut each stem. Loppers are effective for small clones. I’ve found that with sumac, you can actually snap off the stems in many cases (but be prepared to have the juices stain anything it gets on). Depending on the size of the stems, a Parsnip Predator can be used to cut the stems.

Where to Cut

Another variable to consider is the height of the cut. I’ve varied this as well, from ground level to 2-3 foot high. Cutting to ground level results in fleshy resprouts that can easily be second-cut with a Parsnip Predator. The really high cut was done to encourage resprouting only on the stem and to test if you get less new stems from the roots. This method allowed a second cut of a single stem, rather than the cluster of resprouts that come from the base. With this method, I found that the stem sprouts can sometimes just be snapped or stripped off, especially with sumac. The disadvantages are that some of the energy in the stem is retained, and the resprouts are not shaded by other vegetation. The method seemed to work as well as cutting lower on the stem in areas of sparser vegetation.

But Does it Work?

How effective is double-cutting on clonal species? I use it only on aspen and sumac; it’s been found to be ineffective on black locust. Because these two species are native, I’m not really all that concerned with eradication. However, I have eradicated many clones using double-cutting (with no herbicide), but most of those required several years of double-cutting. In one case, a single double-cutting killed a sumac clone. This was an older clone, so include that as one of the variables that might contribute to success when using double-cutting.

You might consider herbicides if you want more certainty in eradication. However, as Tom Brock pointed out in his management work (read here), even with herbicide it is a multi-year effort. For myself, I like the opportunity to control a native invading species without the use of chemicals. However, for the double-cutting to be effective, you must be timing the cuttings correctly, be cutting all of the stems in the clone, and continue the process as long as needed.

Read about other non-herbicide management techniques like using a Parsnip Predator, or girdling.

Controlling biennial invasives without herbicide using a Parsnip Predator

Controlling biennial invasives without herbicide using a Parsnip Predator

Controlling Biennial

Invasives Without Herbicide

Using A Parsnip Predator

By Jim Rogala

Predator and burdock root - PC Rob Baller

My recent blog post on girdling got me thinking about other herbicide-free invasive species control methods. For biennials, there are three common mechanical control methods: mowing, pulling, and cutting below the root crown. Mowing is favored for large infestations because of the daunting task of methods used on individual plants. Pulling or root severing is feasible on small infestations. For some biennials, such as sweet clover, pulling works if conditions are right. However, there are some species where pulling is not that effective, and in those cases, root severing is a better method. In this post, I’ll discuss using root severing as a method to control biennials.

How it Works

As with girdling, the control of biennials also takes advantage of the plant’s anatomy and physiology to kill plants without using herbicides. In this case, we take advantage of the inability of many biennials to re-sprout if cut at some depth below ground level. These plants typically have taproots with all the adventitious buds (the source of re-sprouting) near the soil surface, thus allowing all the buds to be removed with below-ground cutting. Technically, many of these can live more than two years (they live until they flower), but without resprouts they are dead. Typically, cutting 2” or more below the root crown will suffice, but in some cases, I’ve found it successful at even less than 2”. There are many factors that affect resprouting, such as growth stage, nutrient storage, and other simultaneous stressors (e.g., shading), so keep these in mind as you decide how deep you need to go.

 

How to Cut the Crown

So, how does someone efficiently cut a root under the ground? The Parsnip Predator is a modified shovel that was designed specifically for this purpose by The Prairie Enthusiasts Prairie Bluff Chapter. Though obviously designed for wild parsnip, I’ve used it on other biennials such as sweet clover, burdock, and biennial thistles. I also find it handy to use on some annuals to minimize seed production, and for some perennials to set them back. I even use it for above ground severing of young tree sprouts when I’m double-cutting species such as aspen and sumac. I actually seldom use it as one would typically use a shovel, but rather just thrust the blade into the ground at an angle through the root of biennials or through the stems of perennials (and tree resprouts).

There are some advantages of root severing as opposed to other mechanical methods. As opposed to mowing, the severing allows the surrounding vegetation to stay intact, therefore not only leaving desirable species unharmed but providing shading of the potential resprouting biennial. Even though the repeated thrusting of the shovel is hard on the body, I find it less abusive than the constant bending over to pull biennials. And when it comes to parsnip, I like the idea of not having to grab a plant that has harmful juices in it! It can also be done under most soil moisture conditions, whereas pulling works best in moist soils.

The next time you need to address problems with biennials, consider using root severing to your potential management approaches and add a Parsnip Predator (or two!) to your toolshed.

Get Your Parsnip Predator Today!

Nate Lee holding a Parsnip Predator - Photo by Sarah Barrona

Watch this video to see the Parsnip Predator in action!

Spring is the time for girdling

Spring is the time for girdling

Jim Rogala

The intense transfer of materials within a tree at this time of the year makes for efficient girdling. Girdling is simply the removal of the “bark” to kill a tree. I use girdling as my go-to method for killing aspens clones. The method works best on clones where stems are at least an inch or two, although it can be used in combination with double cutting of the smaller stems (a topic for another post). It is critical to girdle all stems of a clone. I use it on a number of other species, including birch, but it doesn’t work on all species (e.g., box elder).

The key to successful girdling without using herbicide is to remove the outer layers (inner and outer bark) of the truck without injuring the innermost parts. I’ll bore you with the plant anatomy and physiology details in a later paragraph, but the details are really unneeded to accomplish the mission at this time of year. There is an obvious break between these layers when the tree is translocating a lot of materials upward, which is happening now. A person can simply run a tool between these layers around the entire circumference with a span of at least 6 inches wide. There’s no need to have clean cuts on the upper and lower ends of the separation, with the end-product often being somewhat banana-peeled looking.

There are a variety of tools that can be used to girdle, but from the description of the process above it’s obvious that a chainsaw is not one of them. For smaller trees, I often use a somewhat dull wide-bladed wood chisel. For larger trees, I use a flat pry-bar or a leaf spring cut to a manageable size and sharpened on one end. First I use the tool vertically to open an area to access the location between the layers, but this should be done without cutting too deeply into the tree. Then, put the tool between the layers horizontally and work it around the tree.

For those of you that are curious, here’s why this method works. There is a lot of specificity in the cells of a tree. There are those that transport materials upward in the inner layers (the xylem), and those that transport materials downward in the outer layer (phloem). Products stored in the roots, along with water, are sent upward. Products generated by photosynthesis in the leaves are sent downward. By removing the outer layer, the plant starves to death without the translocation of nutrients to the roots. You might be thinking that just cutting the tree might serve the same purpose. Well, that’s true for some species (such as cedars), but most trees have a strategy that includes resprouting from the base (or, like aspen, from rhizomes) when the xylem is disturbed. Be patient when looking for the results, as the tree will appear fine until the need for nutrients from the roots becomes great in the following spring. Sometimes it might take two years for the tree to die.

More information on girdling can be found by searching the web, but be careful to look for methods similar to what I’ve described here that don’t use herbicide. Tom Brock has a section on this topic on the Pleasant Valley Conservancy website (http://pleasantvalleyconservancy.org/brushandtrees.html). This method is not only effective, but minimizes the use of herbicides, which is attractive to me.