Gypsy moth (Lymantria dispar) treatment is happening in Lafayette County, beginning mid-May through August. The day before receiving this announcement, I discovered a rusty-patched bumble bee (Bombus affinis) on our property, a federally endangered insect. While this was a new find, our land supports a number of classified insects (endangered, threatened, and special concern, also referred to as T&E), along with herptiles and birds. Needless to say, I was concerned and had to nail down the details.

If you received a notice about spraying in your county, you can check to see the target sites with the Department of Agriculture (DATCP) interactive map.

What is the killing agent?

Bacillus thuringiensis serotype kurstaki (Btk) is a group of bacteria which makes it a biological control agent. This bio-control agent is different from those where a non-native insect is brought in to kill off a non-native plant. All bio-control measures need a healthy dose of skepticism applied to them — two non-natives don’t make a native. Since Btk is commonly found in our soils, it does not introduce a foreign entity into our ecosystems.

How does Btk work?

I went in search of how Btk does the “dirty deed.” Btk is not a contact insecticide; the insect must ingest it. It is a stomach poison and will only effect the larval feeding stage (i.e., when it is a caterpillar). Andrea Diss-Torrance, Invasive Forest Insects Program Coordinator for the Wisconsin DNR, tells me that “among moths and butterflies, the effect can vary: about a third of species tested are sensitive, about a third are not [a]ffected at all, and about a third have an intermediate level of sensitivity. Btk is degraded by sunlight and very sensitive caterpillars, such as the Eastern tent caterpillar, are no longer [a]ffected about 11 days after application to foliage”(Andrea Diss-Torrance, personal communication, May 3, 2018).

“When Btk is ingested by a susceptible caterpillar, the highly alkaline environment of the caterpillar’s gut triggers the Btk bacterium to release a crystalline protein called an “endotoxin” that poisons the insect’s digestive system. The endotoxin acts by killing cells and dissolving holes in the lining of the insect’s gut. When a mixture of food, Btk spores, and digestive juices leaks through these holes into the insect’s blood, it causes a general infection that kills the caterpillar. Humans and other mammals have highly acidic environments in their stomachs that destroy Btk before it causes infection” (Ellis 2018).

Two types of Btk mixtures

There are two commercial brands of bio-control mixtures being used against the Gypsy Moth: Foray48® and Gypchek®. The DNR determines which to use based on insects listed in the Natural Heritage Inventory. I have repeatedly expressed my concern with this methodology. Current lists for Lafayette County will be insufficient to ascertain if classified species exist because our county is incredibly undersurveyed for insects (and plants for that matter). I suspect few counties have insect surveys covering the county.

Christopher Foelker, Gypsy Moth Unit Supervisor for DATCP, tells me Gypchek® is used in habitats having known T&E species that are in a vulnerable life stage during the treatment times. (Christopher Foelker, personal communication, May 3, 2018). DATCP considers Gypchek® to be less effective than Btk because it deteriorates quickly and has a much shorter window of efficacy. It is a viral insecticide that is specific to the gypsy moth but it iscostly to produce and there are limited amounts. It is manufactured by raising and infecting gypsy moth caterpillars with a virus (NPV-gypsy moth). These infected caterpillars are ground up and suspended in a liquid solution. This solution is Gypchek® and it is applied to the tree canopy.

Since it is a limited resource, state and federal governments agree to use Gypchek® only where rare species are known and not on every area proposed for Btk treatment. Unless a T&E insect is known, Foray48® is used.

Foelker says all the DATCP treatment plans are reviewed by the US Fish and Wildlife and US Forest Service for any potential effects on T&E species. They present any concerns for areas these species might be impacted.

Who else is affected?

Since I seldom take info from just one source, I continued my sleuthing on this topic. Jay Watson, who works in the Bureau of Natural Heritage Conservation,confirmed my suspicions, “Really, the impacts from Btk on other insects is very poorly understood.  I don’t know of any research that has looked at what impact this might have on insects like bumble bees.” (Jay Watson, personal communication, May 3, 2018). He specifically mentioned bumble bees because of our recently discovered rusty-patched bumble bee on our property.

There are two sides to every issue; this one is no different. Diss-Torrance stated, “the effect, or in this case non-effect, of Btk on a wide range of other creatures is very well known as this bacterially based insecticide has been used extensively in agriculture and forestry since the ‘80’s.”

In general, sunlight and other microbes destroy Btk applied to foliage within three to five days, so Btk does not multiply or accumulate in the environment (Ellis 2018). Yet, in a 1998 study, Btk was added to different types of soil in order to determine how the type of soil affected the persistence and concentration of Btk. The results of the study showed insecticidal activity started to decline after a month in one soil, while in another, toxicity was high after six months. The authors of the study noted that even though Btk is considered non-toxic to non-target species, the accumulation and persistence of the Btk toxins could eventually lead to environmental hazards or the selection of Btk-resistant lepidopterans (Wikipedia 2018).

The EPA has studies demonstrating a small level of toxicity to certain fish, a slight toxicity to honey bees at high level doses, and “practically non toxic” at low level doses. It is slightly toxic to the convergent lady beetle (Hippodamia convergens) (EPA 1998). Caterpillars that become ill or die after ingesting Btk are not considered dangerous to birds or other animals that feed on them (Ellis 2018).

I wasn’t thinking there would be a moral to this story when I began researching it, but I believe that there it. The value of citizen science is priceless and saves lives. Wisconsin DNR’s decision-making about gypsy moth treatments relies solely on the information at the Natural Heritage Inventory. The information behind many decisions that mitigate impacts to our natural community and our T&E community originates from citizen scientists.

Sources:

Ellis, Jodie A. (04 May 2018). Exotic Insects Education Coordinator Department of Entomology, Purdue University. Retrieved from https://extension.entm.purdue.edu/GM/PDF/GMquestions.pdf

Entomological Society of America. (May 2018). Is Bt safe for humans to eat?

Environmental Protection Agency. (1998). EPA 6452 Fact Sheet. Retrieved fromhttps://www3.epa.gov/pesticides/chem_search/reg_actions/registration/fs_PC-006452_01-Aug-98.pdf

Tobin, Patrick C. and Andrew M. Leibhold. “Gypsy Moth” in Encyclopedia of Biological Invasions. (Los Angeles: University of California, 2011): 298-304.

Wikipedia. (04 May 2018). Retrieved from https://en.wikipedia.org/wiki/Bacillus_thuringiensis_kurstaki

We all know the damaged non-native invasive species do. They exclude our native species — insects, plants, animals and other biota – reducing biodiversity, reducing crop yields, reducing recreational enjoyment of our waters, and lowering land values. 

While awareness of the damage invasives do has expanded, it isn’t always clear what we as individuals can do. With the technology of smart phones and tablets, there is a fun new app available to help map locations of invasions. This app is the Great Lake Early Detection Network (GLEDN) and has been developed specifically for our area.

It’s an easy-to-use and intuitive app. Wisconsin First Detector Network (WIFDN) has videos to assist with downloading the app and getting started. Once the app is downloaded, you can choose from these categories: aquatics, birds, crustaceons, diseases, fish, grasses, herb/forbs, and insects.

Embedded in the app is a fact sheet about each species. Each fact sheet includes photos, species descriptions, currently mapped locations of infestations and an explanation of why it’s an ecological threat.

Data is collected with a single point or with a polygon. The larger infestations are noted with a polygon which can be drawn to the exact shape of the invasion. If you use the polygon option, the app calculates the size of the infestation. Each record automatically ascertains the GPS points using the WSG84 datum format.

Each record is verified so a photo is required. This verification process ensures the credibility of the records.

You can create your own species list or use one generated for the Great Lakes region. You also have the choice to use the scientific name or the common name. You can note the habitat types and note the infestation’s density – low, medium, or high.

Once finished collecting the data, each report needs to be specifically submitted. Until it is, the info remains stored in your phone or tablet. This is a valuable option because you don’t need to use the data on your phone plan to submit the reports; you can wait until you have a wi-fi connection. Reports can be uploaded all at once or one at a time. The biggest downfall is there is no spinning circle to alert you that the upload is in progress. Patience is required. You will see a message on your screen when the upload is complete.

GLEDN can assist land managers especially with large tracts of land. One can decide if any and all species will be reported or only a select few. Once GLEDN has assisted with the documentation, management activities on these patches of invasives can be tracked with the Invasive Species Management Tracking System (ISMTrack). The annual cost for the management software is very reasonable. For a private landowner using ISMTrack on their property, the fee is $25/year. For non-profits, the cost is $50/site or $200 for 5+ sites. Contact WIFDN for training and additional information.

Data from this app is used inconjunction with EDDMaps (Early Detection & Distribution Mapping System), a national database of invasive species. Once the data is collected using GLEDN, downloading toEDDMaps provides mapping capabilities without needing GIS software knowledge. Additionally, as a national database, it allows us to see trends and species movement.

Common St Johnswort (Hypericum perfolatum) is native to Europe, Asia, and Africa. It is also known as Klamath weed, goatweed, and dotted St Johnswort (because the leaves are dotted). Introduced as a garden ornamental, it was discovered in 1793 in Pennsylvania. How many invasives can you name that were introduced in this manner? Seven US states consider is a noxious weed. As with many non-natives, Common St Johnswort has no substantiated value for wildlife as food or as cover. In fact, it is dangerous to livestock and birds do not feed on the fruiting parts either.

Common St. Johnswort contains hypericin

The danger to livestock is because the plant contains a chemical called hypericin. This chemical creates light sensitivity to lightly pigmented areas of livestock  – the mouth, nose, ears, and udders. Sheep, cattle, horses, and goats are susceptible; goats are more resistant than others. Their skin blisters, they lose hair, and generate a fever; they experience rapid pulse and respiration rates, increased salivation and diarrhea. Affected animals may die of dehydration or starvation because of swelling and soreness of the mouth.

Where it Prefers to Grow

Common St Johnswort likes full or partial sun and grows in a variety of soil types. It is found in grasslands and forested areas in North America. It does not like competition and establishes quickly where disturbance has created bare soil (e.g. animal scratches, burned areas, and new plantings). It also favors high soil moisture and wet seasons. Bosy and Reader (1995) found that a covering of grass litter significantly reduced germination and shoot extension.

Physiology of Common St. Johnswort

A single Common St Johnswort plant can have many aboveground vegetative parts strung together   with a system of vertical and lateral roots. This root system is extensive. It starts by putting down a taproot that extends 2 to 5 feet deep. The lateral root growth is shallow, usually 0.5 to 3 inches below the soil surface. In autumn and spring or following plant injury, these lateral roots produce buds from which new plants develop. These new plants can be as far as 3 feet from the parent plant with sprouting in between. Each seedling eventually matures and becomes independent, developing up to 30 stems per parent plant. This massive root system with its numerous young sprouts create an impenetrable mat near each parent plant. 

Seedlings of Common St. Johnswort are very small and grow slowly compared to seedlings of other plants. This slow growth makes seedlings susceptible to competition for light, nutrients, space, and moisture from not only the mature parent plant, but independent Common St. Johnswort plants and other species. Drought will severely reduce seedlings but when moisture levels are favorable an abundance of seedlings can be found.

Reproduction

Reproduction occurs via self-pollination as well as pollination by a variety of insects. Regeneration also occurs via vegetative propagation and is stimulated by disturbance (e.g. grazing, fire, mowing). Vegetative propagation can occur from the root fragments, the root crown, or sprouting from the lateral roots.

Common St Johnswort does not flower or produce seeds until the 2nd year. That is not much relief since estimates of seed production range from 15,000 to 34,000 seeds per plant with an average of 23,350 seeds (Tisdale et al. 1959). Variation in seed production is a function of site factors, seasonal growth conditions, and the level of disturbance and competition. That multiplies quickly when considering each plant can have 30 stems and each stem can contain 25-100 flowers! The seeds are produced in pods or capsules, which average to about 73 pods per plant (Compton et al. 1988).

We know from laboratory experiments and field studies that Hypericum seeds persist in the soil for many years. Some results suggest seeds of Hypericum species remain viable in the soil for more than 50 years (War et al. 1994). While germination is highest when the seeds are in the top half inch of the soil, they will germinate when they are 3 inches deep (Tisdale et al. 1959). Germination can occur in spring, fall, or winter and takes an average of 1 to 2 weeks. I have found young seedlings and plants in full bloom alongside plants setting seed.

Dispersal can be by wind, water, humans, and other animals. The pod or seed capsule has a sticky exudate which aids in two ways. It adheres the seed to something or someone and doesn’t allow the seed to germinate until this coat is removed by wear or water. Viability after storage is high; 94% germination after 5 years and 50% germination after 16 years.

How to Control Common St Johnswort

As with all non-natives and invasives, control must be sustained. Infested areas must be monitored each year. With this particular plant, keeping disturbance to a minimum is helpful until the infestation can be brought under control.

Cutting and mowing are ineffective as management methods for Common St Johnswort since sprouting may occur immediately after crown removal or defoliation. Mowing also negatively affects surrounding plants that could outcompete with it if allowed to grow and set seed. As with most other invasives I’ve been researching (i.e. Ox-eye daisy, spotted knapweed, Queen Anne’s lace), burning could increase the density and vigor of these plants, thereby increasing the area of their infestations. If you use prescribed fire for other management reasons, be sure you schedule time for the requisite follow up.

I have found mechanical removal to be the most effective. It does leave soil disturbance but if done early enough in the spring, this provides space for the native plants. One can always overseed these areas in the fall, too. Because any root segments left on the soil surface could sprout, be sure to carry your pulled plants out.

Coupled with hand pulling, if I break off the taproot or leave a portion of a lateral root exposed, a spritz of 20% triclopyr in bark oil will ensure a new plant will not sprout. If the clump is large, to mitigate soil disturbance, I will lop it off at the base and spritz it with the tricolpyr mixture. Metsulfuron is another chemical that will kill the plants. It is usually applied foliarly and is successful with large clumps. The small leaves of first-year plants make foliar spraying difficult to do without a good deal of collateral damage; hand pulling is best for these. Once in flower, an application of 20% glyphosate on the cut tops of the stem (much like the Canada goldenrod control method) has been known to work, but it’s tedious because of the number of stems per plant.

Persistence does pay off! We have been able to reduce the number of these plants at Driftless Prairies with annual monitoring and treatment.

References

Bosy, J. L.; Reader, R. J. 1995. Mechanisms underlying the suppression of forb seedling emergence by grass (Poa pratensis) litter. Functional Ecology. 9(4): 635-639.

Crompton, C. W.; Hall, I. V.; Jensen, K. I. N.; Hilderbrand, P. D. 1988. The biology of Canadian weeds. 83. Hypericum perfolatum L. Canadian Journal of Plant Science. 68(1): 149-162.

NRCS Plant Guide http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.370.857&rep=rep1&type=pdf (Accessed 10 Jun 2016)

Rice, Barry Meyers; Randall, John. 2004. Weed report: Hypericum perforlatum–St. Johnswort, Klamath weed. In: Wildland weeds management and research: 1998-99 weed survey. Davis, CA: The Nature Conservancy, Wildland Invasive Species Program. 7 p. On file with: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory, Missoula, MT.

Tisdale, E. W.; Hironaka, M.; Pringle, W. L. 1959. Observations on the autecology of Hypericum perfolatum. Ecology. 40(1): 54-62.

Warr, Susan J.; Kent, Martin; Thompson, Ken. 1994. Seed bank composition and variability in five woodlands in south-west England. Journal of Biogeography. 21(2): 151-168.

Zouhar, Kris. 2004. Hypericum perfolatum. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/ [2016, June 10].

http://www.fs.fed.us/database/feis/plants/forb/hypper/all.html (Accessed 10 Jun 2016)

Oxeye daisy (Leucanthemum vulgare) is a perennial, herbaceous, non-native plant growing 1 to 3 feet tall with showy white flowers. It was introduced from Europe as an ornamental plant and as seeds contaminating cereal crops. It has spread profusely across the world and is a non-native in 40 countries and every state in the U.S. Oxeye daisies survives in a wide variety of soil types, climates, and other environmental conditions. Frost and drought do not affect this plant.

These are easy plants to recognize. Their alternate clasping leaves are toothed and become narrower toward the top. The basal leaves are spoon-shaped.  The white flowers are usually what catches my attention but very unique leaf pattern does as well when I’m doing my early spring spot check.

The previous botanical name, Chrysanthemum leucanthemum, means “gold flower white flower.” The current name, Leucanthemum vulgare means “common white flower.” It also has several common names: bull daisy, button daisy, dog daisy, field daisy, goldens, marguerite, midsummer daisy, moon flower, and white weed.

Their Growth Habit

Oxeye daisy spreads by seeds, by rhizomes, and by adventitious roots. The roots are shallow and grow rapidly, forming a dense mat that leaves no space for the native plants. If you pull up a large clump, it creates a good deal of soil disturbance as well as a shallow hole. Often when hand pulling, the individual stems easily break off from the main clump. If you leave one stem, you’ll be back again!

Oxeye daisy has 2 growth periods – spring and fall — and germination occurs throughout the growing season. The report from the Washington State Noxious Weed Control Board states 90-95% will germinate at 68 degrees F. Fall is when most seedlings establish.  First year plants will remain in the rosette stage until after a cold winter which initiates blooming. It is this rosette stage that certain foliar herbicides can be applied.

On average a plant can produce 1,300- 4,000 seeds and large, hearty plants have yielded up to 26,000 seeds! (Howarth and Williams 1968). These seeds are highly viable and can remain so up to 39 years although the percentage of viability drops after 6 years. Champness and Morris (1948) found one million seeds per 2.5 acres in ag fields and up to 4.2 million seeds per 2.5 acres in grasslands.

Control Options

Control must be done immediately as these plants can spread quite rapidly. Grazing is not very effective. Horses, sheep, and goats will eat oxeye daisy and the viability of the seed is reduced when passing through the animal, but it is not killed. Cows and pigs generally avoid oxeye daisies. If a milk cow does eat it their milk has an off flavor to it.

Mowing does not successfully kill oxeye daisies. Like Queen Anne’s lace, it will prevent the mowed bloom from setting seed, but the plant will survive and bloom again only at a height short enough the mower blades have no effect.

Prescribed burns aren’t effective either. The disturbance and open spaces resulting from burns make this management tool ineffective and could lead to further infestation.

Daisies are resistant to many herbicides but I have had good luck with Opensight® on first year plants in the rosette stage. Once in bloom, hand pulling is the best control with the caveat that one has to get all the seedlings around it and not miss one of those stems that has curved out and away from the initial group. Fortunately, they are easy enough to identify since they have an interesting purple striped pattern.

If I find hand pulling results in too much soil disturbance, another technique I’ve used successfully with the large clumps is to cut them low to the ground and spritz with triclopyr (either Garlon 4® or Progeny®) in bark oil. I use this same technique with Hypericum perfolatum, Common St. John’s wort.

One last word of caution – if you’re buying pre-mixed, pre-packaged seed Oxeye daisy could well be in the mix. Be sure you know each species in the mix and source your seeds from a company specializing in native plant restoration.

References:

Champness, S.S. and K. Morris. 1948. The population of buried viable seeds in relation to contrasting pasture and soil types. Journal of Ecology 36: 149-173.

Howarth, S.E. and J.T. Williams. 1968. Biological flora of the British Isles. Journal of Ecology 56: 585-595.

Washington State Noxious Weed Control Board. 2000. Written findings of Leucanthemum vulgare. www.nwcb.wa.gov/siteFiles/leucantheum_vulgare.pdf. Accessed 04 June 2016

This article appeared in the May 5, 2016 Pectonica Valley Leader newspaper. I’ve transcribed it here as well as included a photo of the article.

By Gary McKenzie

Blanchardville couple Jim and Marci Hess are active members in Southern Wisconsin’s Trout Unlimited and the duo helped coordinate a recent effort – bringing in some extra able-bodied help in a river valley restoration maintenance project taking place – and continuing, approximately 6,5 miles north of Blanchardville in the “Kittleson Valley” region that’s near the Hwy H and Hwy 78 N intersection.

Anyone driving through the area the past half dozen year will well remember when heavy equipment came in, cleared huge trees out of/off of the river banks and cleared/stacked downed trees that had fallen into or onto riverbanks.

But in years since, invasive species, weeds and unwanted plant growth had reappeared and Jim and Marci Hess had volunteered to hep [sic] clear the area again and to begin readying the are for re-introduction of more desirable grass varieties, often from seeds they had gathered from their own native grass stands.

Following an autumn burn down (on the pre-existing reed and canary grasses) helpers from “Operation Fresh Start” assisted the Hess’s in clearing the area, preparing the area for future planting of cord grass and blue joint grass.

Operation Fresh Start is the organization Southern Wisc Trout Unlimited (SWTU) is working with, Jim and Marci Hess are leading this effort on the easement that steward for the SWTU Streamkeepers programs.

Mrs. Hess notes the Operation Fresh Start folks helped out in April and will return for another week in June.

The work group consisted of 6 or 7 young folks who are often young people who for whatever the reason had dropped out of high school – and have since joined the Operation Fresh Start programming, working toward their high school equivalency diplomas, attending classes parts of each day – and being paid for physical work on partial days – out and about in the community.

“The 2 grasses we are planting plugs of are blue joint grass (Calamagrostis canadensis) and cord grass (Spartina pectinata). This planting will happen in early June. We will be overseeding with around 30 other types of seeds that Jim and I hand collected last fall and have been cold, moist stratifying this winter. We didn’t throw them out in fall as we would normally because we wanted to herbicide for reed canarygrass, wild parsnip, and Canada thistle first. We will be overseeding and adding plugs each year.

The Hess’s have utilized Embrace the Stream components in cleaning up stream and river banks instead of letting them go, so to speak.

Embrace-A-Stream (EAS) is a matching grant program administered by Trout Unlimited that awards funds to TU chapters and councils for coldwater fisheries conservation. Since its inception in 1975, EAS has funded more than 1,000 individual projects for a total of $4.4 million in direct cash grants. Local TU chapters and councils contributed an additional $13 million in case and in-kind services to EAS funded projects, for a total investment of more than $17 million. In the 2015-16 grant cycle, a total of $84,941 was awarded to 26 chapters and councils, with an average grant award of $3,267, helping restore stream habitat, improving fish passage, and protecting water quality in 18 different states from coast to coast.

(Editor’s note: Jim and Marci Hess own 46 acres of native habitat in The Driftless Area and with along [sic] their background and journey into prairie, woodland, and savanna restoration, they are strong advocates for streambank restoration projects. Learn more at: www.driftlessprairies.org)

This agricultural weed is originally from Eurasia. It is found across most of the United States on abandoned cultivated lands and, in our case, a prairie restoration in a once-cultivated field. It won’t tolerate plowing, but the seed must remain viable for several years.

The meaning of the species name is “common or generally accessible;” I prefer to take it more literally and call it “vulgar” as in offensive or indecent! The name “chickweed” comes from plants used as starter feed for chicks.

This particular chickweed gets its common name from the cute little fuzzy leaves that resemble mouse ears. But when it’s on your land, there isn’t anything cute about it. It spreads by seeds and rootlets which are set down from the spreading arms of this mat-forming plant. C. vulgatum blooms from spring to fall as long as it’s cool and moist. This sun-loving plant will form a green mat is very little time and will shade out germinating prairie plant seeds. I have not been in the right place at the right time to know when one first comes up to time how many days before it covers a certain area. We’ve had a fairly warm, early spring this year (2016) with maybe 15 days of greening up. With that said, the picture below shows how quickly this chickweed can spread.

Because this plant grows by hugging the ground and spreading out, the best control is by herbicides. Mowing close cuts the first blooms off but further mowing encourages its low creeping habit. A 2% mixture of glyphosate is sufficient to kill the plant. It’s important to do this when it first pops up from the ground. Its blanketing effect is sufficiently quick that herbiciding it at this stage creates “deserts” – areas of barren ground. When this happens, you can overseed or plant seedlings in the area.