The Case of the Undead Buckthorn (Foliar Treatments with Triclopyr Herbicide)

By: Julianne Mason, Restoration Program Coordinator, Forest Preserve District of Will County

We have had a recurring issue over the past decade with common buckthorn (Rhamnus cathartica) not truly dying after being foliar treated with triclopyr 3A herbicide in dolomite prairie habitats.  The buckthorns are 2-5’ tall, multi-stemmed re-sprouts that have been repeatedly top-killed by fire over the past several decades.  The buckthorns appear to die properly at first.  After the foliar herbicide treatment, the leaves yellow, then turn brown and fall off prematurely.  However, lots of the shrubs re-sprout vigorously the following year.  This has happened with foliar treatments done in the early summer, late summer, and fall.  Apparently buckthorn is a calciphile in its native habitat, so perhaps it is just particularly hard to kill in calcareous habitats here?  Has anyone else observed buckthorn or other invasive shrubs appearing to die after foliar herbicide treatments, only to rebound vigorously the following year?

Photo 1 caption:  Undead buckthorn.  Many of the buckthorns that had been foliar treated with triclopyr herbicide re-sprouted vigorously the following year.  Photo taken a year after the herbicide treatment.

Buckthorn does seem to die reliably from cut stump and basal bark treatments of triclopyr 4 herbicide in bark oil, in the same dolomite prairie habitats.  Therefore, I hypothesized that perhaps the ester formulation of triclopyr might be more effective than the amine formulation.  To test out this theory, I marked buckthorns that were foliar treated with triclopyr 3A or triclopyr 4 at concentrations of 2%, 5%, or 10% during September 2018 at Lockport Prairie.  All treatments included 1% MSO and 0.4% PenATrate II surfactants.  Around 50-100 shrubs were included in each treatment.  We put color coded flagging on each treated buckthorn to keep track of its treatment type.

All of the treated shrubs appeared to die after treatment; their leaves turned brown and fell off prematurely last fall.  However, many of them rebounded vigorously the following spring.  Contrary to my expectation, I didn’t see any significant difference in mortality rates between the two different formulations of triclopyr (3A or 4), as evaluated 1 year after treatment (YAT).  However, there was greater mortality using the 10% concentration of triclopyr herbicide compared to lower rates.

2% Concentration.  Despite the promising results immediately after treatment,  less than 10% of the buckthorns that had been foliar treated with 2% triclopyr were dead this summer (1 YAT); nearly half of them had re-sprouted vigorously from the base while the rest of them fully leafed out from the top.

5% Concentration.  Less than 25% of the buckthorns that had been foliar treated with 5% triclopyr were dead this summer (1 YAT).  Around one quarter of them fully leafed out from the top, while around half of them resprouted vigorously from the base. 

10% Concentration.  Around 70% of the buckthorns that had been foliar treated with 10% triclopyr were dead this summer (1 YAT).  Conversely, nearly one-third of the treated buckthorns had resprouted and were still alive.

Based on these results, I would recommend using 10% triclopyr as a foliar treatment and be sure to follow up on re-sprouting individuals the next year.  Or, I might try basal bark/base spraying them with triclopyr 4 in an oil-water emulsion.

https://grasslandrestorationnetwork.org/2018/11/08/julianne-mason-on-basal-bark-applications-using-an-oil-water-emulsion/

Bottom Line:  Beware of invasive shrubs appearing to die right after foliar herbicide treatments, only to re-sprout the following year.  Has anyone else experienced a similar thing with buckthorn or other invasive shrubs?  I find it hard to believe that our buckthorns are truly unique.  It is a shame to spend time and money on treatments that are not effective.  Plus, herbicide treatments cause collateral damage to other plants.  It is a double shame to kill off-target species and not actually achieve the goal of addressing the invasive species population.  Mark some of your foliar treated shrubs and check them next year to make sure that the treatment actually worked.  Do you have undead invasive shrubs too??

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2019 GRN Workshop Schedule

MONDAY, AUGUST 19, 2019

5 p.m. pre-workshop dinner at Heartland Grill in the Sheraton Madison

Connect with other attendees at a casual dinner and social time. (Note: this event is not covered by conference fee.)

 

TUESDAY, AUGUST 20, 2019

8:30 a.m. Workshop check-in and continental breakfast

UW Arboretum Visitor Center auditorium

 

9 a.m. Welcome

Opening remarks by Bill Kleiman and Chris Helzer of the GRN. Opening remarks by Arboretum Director Karen Oberhauser. Discussion of logistics and agenda by Mike Hansen

 

9:15 a.m. Arboretum land management and research

Presented by Michael Hansen and Brad Herrick

 

10 a.m. Restoring and protecting monarch habitat: suburban gardens aren’t enough

Presented by Karen Oberhauser

 

10:45 a.m. break

 

11 a.m. Pollinator conservation

Presented by Susan Carpenter, Arboretum native plant gardener

 

11:45 a.m. Lunch

 

12:45 p.m. Tours

Tour A: Aldo Leopold Foundation, Baraboo

Tour B: Faville Grove Sanctuary (Madison Audubon Society), Lake Mills

Tour C: Military Ridge Prairie Heritage Area (The Nature Conservancy, The Prairie Enthusiasts). Thomson Prairie, Blue Mounds; Mounds View and Barneveld Prairies, Barneveld

 

~5:30 p.m. (as buses return from field tours) – Social gathering

Arboretum Visitor Center auditorium

 

6 p.m. Dinner and cash bar

Arboretum Visitor Center auditorium

 

8:30 p.m. Day 1 end

 

 

WEDNESDAY, AUGUST 21, 2019

8:30 a.m. Continental breakfast

UW Arboretum Visitor Center auditorium

 

8:55 a.m. Welcome back and announcements

 

9 a.m. How seed mix design and first year management influence multifunctionality and cost effectiveness in prairie reconstruction

Presented by Justin Meissen, Tallgrass Prairie Center

 

9:45 a.m. 60 years of change in Wisconsin prairie remnants: resurveying the Curtis dataset

Presented by Amy Alstad, Driftless Area Land Conservancy

 

10:30 a.m. Break

 

10:45 a.m. But how do we get people to CARE?

Presented by Chris Helzer, The Nature Conservancy, Nebraska

 

11:30 a.m. Lunch

 

12:30 p.m. Tours

Tour A: Goose Pond Sanctuary (Madison Audubon Society) and Arlington Agricultural Research Station (UW–Madison College of Agricultural and Life Sciences), Arlington

Tour B: Holy Wisdom Monastery and Walking Iron County Park (Dane County Parks), Middleton and Mazomanie

Tour C: Curtis and Greene Prairies (UW–Madison Arboretum), Madison

 

~4:30 p.m. (as buses return from field tours) – Workshop end

Thank you for coming and safe travels!

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GRN Workshop registration ends August 5

The link below has the agenda and workshop registration.

July 26 was the last day for the discounted block of hotel rooms. But ask for the rate and see what they say. Remember to book a hotel room if you need one.

Registration closes August 5.

Kudos to Mike Hansen for coordinating the workshop!

Grassland Restoration Network 2019 Workshop

 

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Managing invasive cattails by Nathan Herbert

Nathan Herbert

Managing wetland habitat inevitably involves controlling cattails. Recovering a wetland from a well-established cattail colony is a 5-to-10-year project that requires persistence and multiple herbicide application methods. In colonies with a high density of cats, a two person or ATV mounted boom is a good way to cover a large area relatively quickly. With low concern for non-target damage (there is usually little else in dense cattail stands) an herbicide-soaked boom can be dragged over the cattails; literally painting the plants with herbicide. This method can reduce stem density of a cattail colony by 50% or more in two treatment seasons.

As the treatment area recovers, or when managing cats in high quality wetlands, a finer approach is needed to avoid non-target damage. Hand-wicking (aka the Glove of Death) is a popular method to address low density cats. A thick cotton glove wetted with herbicide is worn over a nitrile glove. Individual cattails are then treated by grabbing and pulling them through the glove. When using this method, I use 5% wetland safe glyphosate. There is virtually no non-target damage when treating cattails this way. However, it is not very versatile, and it’s messy. You will get herbicide on your hands, arms, face, and neck despite efforts to minimize exposure.

In most situations, my preferred method for dealing with lower density cattails is to spray the base of the plants with 3-5% glyphosate. Using a sprayer to target individual plants gives you more flexibility in the field. Isolated plants can be targeted with precision and clumps of cattails can be quickly dispatched with a foliar spray (directly to the leaves) if appropriate. This method also has a lower risk of direct contact exposure to herbicide than hand wicking. A one-gallon hand sprayer or a backpack sprayer is appropriate for this method (I’m quite tall and prefer the reach of the backpack sprayer). Apply just a milliliter or two of herbicide to the region of the cattail stem from which the leaves fan out.

Photo 1: Applying a small amount of herbicide to the base of cattail leaves.

I often use my free hand to pull on a few leaves and open the base of the plant. Done this way, herbicide will funnel down into the stem. There is minimal overspray if done carefully and with low pressure. After treatment, fold over the top 6-10 inches of the leaves to mark the plant as treated.

Photo 2 Fold and crease the leaves over to clearly mark the plant as “treated”. This is very helpful when working with a crew; it’s also nice to turn around and see your progress.

As with any established invasive species, eradication is usually not possible. Cattails quickly take advantage of disturbance and changes in hydrology. Exposed muck and soil in wetland restorations is an open door for cats. Quality, remnant wetlands require annual vigilance to prevent cattails from setting up shop. Cattail work is time-consuming and done at the hottest time of year here in the Midwest. Despite that, it is satisfying to see to see the contrast of yellowing cats against the green of other wetland plants. Also, because of their stature and dominant presence, any reductions in cattail density are easily appreciated from year to year. Applying herbicide in a precise, efficient, and tidy manner leaves a smaller management footprint in a wetland and avoids creating an “invasive treadmill.” If you’re looking for a quicker, less messy alternative to hand wicking, give sprayers a chance.

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GRN Workshop Registration deadlines!

The link below has the agenda and workshop registration.

Friday, July 26, is the last day for the discounted block of hotel rooms. Remember to book a hotel room if you need one.

The field trips are filling up fast.

Registration closes August 5.

Kudos to Mike Hansen for coordinating the workshop!

Grassland Restoration Network 2019 Workshop

 

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GRN Workshop Registration Open!

The link below has the agenda and workshop registration.  Remember to book a hotel room if you need one.  Kudos to Mike Hansen for coordinating the workshop!

Grassland Restoration Network 2019 Workshop

 

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Weed spade a mighty tool

Below I am carrying a bottle of broadleaf herbicide in a nail pouch and a “Parsnip Predator” weed spade.  This weed spade is offered by The Prairie Enthusiasts.  They have a nice description online.  The spade is light weight and effective at spading parsnip, poison hemlock, and burdock.  It is also great for loosening soil around sweet clover to make them easier to pull.  You can lean on the spade handle so your back does less work.  You can dig an occasional birdsfoot trefoil.  You dig a tiny hole.

Below is a weed spade with a white sweet clover root. The spade loosens the soil and makes pulling these plants easier on your back.

Below, the right one is the Parsnip Predator weed spade which was made from a standard spade, similar to on left, with metal cut away to make it light weight.    I have one that is a modified Green Guard spade.  Note handle is re-mounted to be 90 degrees which should be easier on the wrist.

Below on the left is a narrow spade I purchased and cut it with a torch and ground it to my liking.  Originally it was a single point to the center and would deflect off of roots.  Here, the center of the tip is notched “upwards” in the middle so the spade stays on the root and cuts it.

These are all Big Box store purchases. That left spade is not good because you can’t get your heal on the spade to push. The others are fine.

Below are a few version we have. The left one is my least favorite with no heal.  Then the orange Ridgid is fine at 4 pounds and looks unbreakable. We have a Jackson J250 that looks the same.  Next, the wood handle Ridgid (and we have a Kodiak brand too) weighs 3.5 pounds,  and the Parsnip Predator of TPE at only 3 pounds.

Which one do you want?   If you have rocky soils the Predator blade can bend and be ruined, but it is shorter and lighter and fits in my vehicile bed easier and I tend to use it. The two in the middle are perfect for young crew with less restraint.

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