Pulling Wild Carrots

The flower head of the Wild Carrot, Daucus carota, is made up of myriad small individual flowers, each capable of yielding a single seed. Since each plant is capable of producing multiple flower heads, a single plant may produce hundreds or even thousands of viable seeds. This may be a lovely proposition for those wishing to expand their population of Wild Carrots, but it can be a headache for people trying to manage areas as native ecosystems. My management efforts aim towards creating conditions that favor the growth and spread of native species. While Wild Carrot may be attractive and a favorite of many people, it is not native to North America and can act to degrade areas into which it invades. In order to protect and improve the native integrity of Blue Jay Barrens, I remove non-native species from the property and that includes ridding the fields of Wild Carrot.

The Wild Carrot is not the only invasive species I work to eradicate during the summer months. Sweet Clover, Teasel and Oxeye Daisy are also on my list of invasive plants to be pulled during the summer months, but they mature at different times through the summer, so multiple visits must be made to each management site during the year.  The photo above shows a collection of plants pulled from a small Prairie area during the first week of June. Plants on the left are Sweet Clover, those in the middle are Oxeye Daisy, and the small pile on the right side is Wild Carrot. Wild Carrot is just becoming noticeable in June as its developing flower stalk begins to elongate.

By the time August 1^st arrives, Wild Carrot plants are a few feet tall and supporting a nice collection of white flowers. All pulled plants are gathered up and placed on an existing brush pile. It wouldn’t hurt anything to leave the plants in place to rot down naturally on the prairie, but doing that makes it difficult to see all of the plants that have not yet been pulled.  I don’t want to risk leaving plants in place that are going to produce seed for future generations. Besides, I enjoy finishing work on a site and then immediately viewing the area in its improved condition.

I always carry a camera with me while I’m working and try to get a few before and after shots. Often the camera doesn’t come out of its holster because I’m racing to finish an area before I run out of time, or I’m sweating so profusely that I’m afraid I’ll ruin the camera if I try to use it. I did make a special effort to take this shot on a fine August morning when the temperature reached 90° F by 10 AM. This is a small section of a 1 acre opening that had never before received any carrot pulling treatment. My success in eliminating invasive summer forbs means that each year I have time to add new areas into my work schedule.

This is the same area with carrots removed. Within a few years the area should pretty much look this way without my having to spend hours pulling carrots.

Wide area shots of these prairie openings rarely show the diversity of plant species present. Spiranthes orchids, such as this pair of Slender Ladies’ Tresses, Spiranthes lacera, were particularly abundant this year.  They are but one of many interesting little species hidden in the tall grass.

Pulling is an effective way of eliminating Wild Carrots because of the plant’s biennial growth habit. The lifespan of the plant is two years. During the first year the plant forms a cluster of basal leaves and establishes its taproot. The abundance of first year plants such as the one shown above gives a good idea of the expanse of plants to be expected in the next year.

A flower stalk develops in the second year. Following pollination, seeds begin to develop as the flower head closes in on itself. Pulling the plants eliminates seed production and reduces the number of flowering plants you will see two years later. Mature seeds that become incorporated into the soil may remain viable for five or six years. Seeds that remain on or near the surface of the soil generally parish if they do not germinate within a couple years. When you begin pulling plants on a new site it takes two years before you really begin to see the positive results of your actions.

Like many plant species that evolved in areas subject to grazing by herd animals, the Wild Carrot has a weak spot in its stem located roughly at the soil surface. If the stem is given a quick pull it breaks at this weak point instead of having its root pulled out of the ground. Just below this breakpoint is a cluster of buds ready to immediately begin producing new flower stalks if the top of the plant is lost. On most occasions, a steady pull will bring the plant up root and all. When you have a particularly tenacious plant or are working in ground that is extremely dry and hard, the carrot often breaks at its weak point. When this happens, I normally use my hand pruners to cut the plant off down into the root slightly below the ground level to avoid the rapid regrowth shown in the photo above.

Often it’s impossible to find the plant stump and regrowth is inevitable. This plant produced two flower heads within four weeks of the plant originally being pulled and broken off at its weak point. I try to make a run through my work areas at 4 to 5 week intervals to catch late developing plants or regrowth situations such as shown here.

Browsing animals, primarily Whitetail Deer, typically bite the plant off well above the soil surface. Browsed plants are particularly difficult to see when you make your first pass through an area, but quickly produce new flower stalks and often account for the majority of late-season flowers.

I found many mature plants that were lying flat on the ground instead of standing in an upright position, making them particularly hard to see. This was primarily a phenomenon of partially shaded areas near the field edges. In the above photo you can see two flower clusters almost at ground-level.  One plant stem comes from the lower right-hand corner the photo and arcs leftward to one of the flower heads and a second plant stem comes from the lower left-hand corner of the photo in a rightward arc to a second flower head. Despite their horizontal growth, both plants are still perfectly capable of producing viable seeds.

This particular area has received a lot of attention in the past few years. A mid-July photo shows no Sweet Clover, no Teasel, and no Wild Carrot. It shouldn’t be too many more years before all the areas have reached this level of control.

I always find a lot of interesting things while I am working and try to stop occasionally to take a few photos. One day I found a number of Poison Ivy Sawflies, Arge humeralis, feeding on the carrot flowers. They were impossible to miss with the sun shining off those bright red abdomens. I’m much more used to seeing the sawfly larvae, so I was pleased to get the opportunity to observe the adults.

The following day, I continued to see adult sawflies, but now I was seeing a different species. On this day it was the Sumac Sawfly, Arge coccinea, that seemed to have staked a claim to the local wild carrot flowers.

Every year I see a couple of Black Swallowtail butterfly larvae feeding on the wild carrots. I took this one and moved it onto a cluster of nearby first year basal leaves.  If they want to continue breeding at Blue Jay Barrens, they will have to select one of their few native host plants.

Eliminating Invasive Plants – Summer Activities

As the seasons change, my management activities change.  Summer is a time to hunt and eliminate invasive forbs and grasses.  Sweet Clover was my initial target several years ago.  As Sweet Clover numbers dropped, I added other species that could be controlled by pulling prior to setting seed.  Now, Yellow and White Sweet Clover, Wild Carrot, Teasel, and Oxeye Daisy are all on my summer pulling schedule.  Not all invasive species can be controlled by pulling.  Sometimes, like in the case of Crown Vetch, the aid of a chemical herbicide is necessary to eliminate the plant.

This is my second year using the chemical Clopyralid in the treatment of Crown Vetch.  Clopyralid kills only broadleaf plants, and is particularly effective on legumes.  Grass is left unharmed, so no bare spots are left in the field after treatment.  The areas I treated this year were fewer in number and much smaller than what I dealt with last year.  Shown above is the largest patch of Crown Vetch I had to spray this year, and it covered only about 40 square feet.

Crown Vetch found its way into my fields as seed that was produced along the edges our township road.  I eliminated the roadside vetch last year, but some of the affected field areas are going to take a bit more work.  Crown Vetch growing beneath the canopy of tall Indian Grass is hard to spot.  The best time to search is when the plants begin to flower.

Unfortunately, peak flowering time for Crown Vetch coincides with flowering of other lavender bloomed plants such as Monarda.  Shown above is Crown Vetch on the left and Monarda on the right.  Colors are almost identical.

Monarda flowers are held above the Indian Grass leaves.  Good luck trying to spot a couple stalks of Crown Vetch hidden down in the grass.

Johnson Grass is another species that requires some herbicide assistance if it is to be eliminated.  I’ve been after this species for several years and only found seven small clumps growing this year.

When dealing with Johnson Grass, I first cut the stalks down to a manageable height and trim back any long, flowing leaves.  This allows me to spray the complete plant with glyphosate, without spraying a lot of neighboring plants.

Johnson Grass is another invasive species that can trace its origin back to the roadside.  Even though the roadside along my property is free of this invasive grass, seed produced along other sections of the road are easily caught and transported by vehicles traveling the roadway.  I expect passersby will replenish my seed supply on an annual basis.

Johnson Grass is hard to miss when it sends up a flower stalk.  This species puts on height in late July, long before the tall prairie grasses, so it doesn’t take much searching to identify new infestations.

When the plant is blooming, tops can be cut and just left in the field.  There is no chance that these flowers will produce viable seed if removed from the plant at this stage.  If treatment is done after seed has formed, it is best to remove the seed heads from the field to eliminate any viable seed being left behind.

I began pulling Wild Carrot six years ago.  I’ve had a lot of success in reducing the numbers of this plant.

Areas that once yielded hundreds of plants, are now producing only a few plants each year.

With fewer plants to pull, I can cover more area.  This is the last of the Wild Carrot infested barrens, an area that I have never had time to get to before.  I was able to finish off this field just as the pulling season came to a close.

Wild Carrot seeds were just beginning to darken during my last week of pulling.  Not knowing if these seeds were developed enough to finish ripening on a pulled plant, I removed the seed heads and bagged them for disposal somewhere other than the middle of my field.

A single Black Swallowtail caterpillar was found on one of the pulled carrots.  I transplanted it to a domesticated carrot variety in my vegetable garden.  It ate for several days and then disappeared.  I hope it went off to find a secure place to pupate. 

Invasive Control - Misc Forbs

In many instances, the simple task of hand pulling is the most effective way of eliminating unwanted plants.  This pile of invasive Sweet Clover, Wild Carrot and Oxeye Daisy was removed from a one acre barrens opening this past summer.  Remnants of last year’s plant collection can be seen beneath this year’s greenery.

This area is typical of the Blue Jay Barrens openings.  Steep, shallow, extremely dry soils present numerous challenges to plant growth.  Invasive plants can become established, but not with the ease or rapidity demonstrated in the former cropland areas.

The welcome mat for invasive plants is in the form of exposed soil, a defining quality of barrens sites.  A seedling that overcomes the other obstacles can grow undisturbed by competing vegetation.  Colonization may be slow, but a persistent species can build quite a population over a period of years.

This is my fourth year of pulling Sweet Clover and Wild Carrot from this site.  Plant removal is quite an effective control method for these species.  They are biennials that form a rosette in year one, then produce seed and die in year two.  If you can halt the production of seed, you can eliminate new generations of plants.  An annual maintenance visit to each site is still necessary to catch any new plants that may emerge.  Sites that I began treating 10+ years ago, now have only a few Sweet Clover plants per acre and virtually no Wild Carrot.  Sweet Clover seed is notorious for persisting in the soil seed bank and remaining viable for decades after falling from the plant.  In order for the seeds to survive for that length of time, they need to be incorporated within the soil profile where they are protected by the ravages of weather and other environmental factors.  I’ve noticed that most of the studies of Sweet Clover seed longevity have been completed on former crop ground, where fresh clover seed could have been neatly buried by common agricultural tillage practices.  Seed produced on the barrens is unlikely to get buried to a depth that would allow it to be protected for extended periods of time.  The seed here stays near the surface and either germinates or dies, so removing plants rapidly produces positive results.

I’ve also been getting more hands-on with the invasive Oxeye Daisy.

I’m still looking for an effective control method in the old crop fields.  The plant is too numerous and too crowded by prairie plants to be easily removed by hand.  There are also too many quality native plants here to make herbicides a viable control alternative.

This Ragged Fringed Orchid, Habenaria lacera, visible in the center or the preceding photo, is just one of many unassuming plants that has found itself being pressured by Oxeye Daisy.

Oxeye Daisy has been slowly making its way into the barrens.  I hand pulled the daisy from a few test areas two years ago, with favorable results.  This year I pulled Oxeye Daisy right along with the clover and carrot.  New daisy plants begin as a basal rosette.  When they’ve stored enough energy, they send up a flower stalk.

Oxeye Daisy removal is totally effective if you leave no viable plant parts in the soil.  This young plant pulled easily and shows no evidence of missing underground parts.

A slightly older plant displays the start of a rhizome that would eventually give rise to new plants.  The stub of a broken rhizome on a pulled plant means that a viable plant part has been left behind to grow a new plant next year.

A single plant will eventually produce a thick colony of plants.  This plant has a single tall flower stalk and three healthy rhizomes.  I think I’ll be able to successfully eliminate Oxeye Daisy from the more rugged barren sites, but I’m still looking for viable control options in other areas.

I’m still collecting seed heads from Teasel in early August, but I also now treat random plants while I’m out doing other invasive species work.  A shot of glyphosate into the center of a basal rosette will kill the plant, or at least damage it enough that it never produces a flower.  Tall plants can be cut and the stump given a little spray of glyphosate.  These two methods would be difficult to apply on a large scale, but are handy to use when finding a handful of plants in an isolated location.  It’s easier to eliminate the plant at the time it is found, than it is to remember to revisit that spot later on to collect seed heads.

Of course, I’m always interested in animals that feed on invasive plants.  I found this stalk borer inside the base of a tall Teasel plant.  I doubt the borer would have killed the plant, but similar borers might be the reason I occasionally find plants broken off at the base.  These broken plants may lay down and hide in the tall grass, but the flower stalks turn upward and still produce plenty of seeds.  Since I have trouble finding these fallen plants, the borer may actually be hindering my control efforts.  Despite minor setbacks, I’m sure that I can eventually get most of these invasive plants under control.

An Annual Wild Carrot Event

Turning my attention to the problem of Wild Carrot, Daucus carota, infestations is an action that I take during mid-summer each year.    I think it’s interesting that this year’s event occurred on exactly the same date as last year’s event.  For two years in a row, August 6 has been the day I began eliminating Wild Carrot at Blue Jay Barrens.

Even though it’s on the list of official Ohio noxious weeds, Wild Carrot is much beloved by many people.  Since its arrival from England, the plant has made itself at home in North America and is perceived by the majority as a natural part of the landscape.  Some of my earliest childhood memories are of running through fields full of Wild Carrot.  When prairie creation was just starting to become popular, Wild Carrot seed was included in many of the prairie mixes.  Wild Carrot is used as a medicinal plant and if you don’t have access to the plant in your neighborhood, there are many sources that will sell you a supply of seed.

The reason for the dark purple flower in the center of the cluster is cause for much speculation.  As a child, I believed the purple flower signified a source of disease.  I spent a lot of time plucking the sick flower from the flower heads.  A currently popular theory is that the dark center imitates and attracts pollinating insects.

Beetles are supposed to be a prime pollinator of Wild Carrot flowers.  It does seem that beetles are frequently found on these flower heads.  However it’s accomplished, Wild Carrot seems to produce an abundance of viable seed.

I’ve been removing Wild Carrots from the prairies for many years.  The plant is a biennial, so several years of pulling severely depletes the available seed supply.  Sometimes, weather extremes help to reduce the population size.  On the dry sites, this year’s number of blooming Wild Carrot plants is quite low.  This is allowing me to clear a lot of areas with minimal work.

Areas that I’ve worked on before are almost cleared of plants.  The drought has hurt many seed producing plants, so seed predators will have to put in extra work this winter to find enough to eat.  I’m hoping that those Wild Carrots that do manage to produce seeds are set upon by some voracious seed eaters.

Wild Carrot plants growing in areas of better soil produce several flower heads.  A single plant may produce thousands of seeds that can become scattered over a large area.  I have hopes of squeezing in a couple full days of carrot pulling during the next week.

The rain showers have softened the soil enough that a large portion of the carrot root can be removed.  It’s easy to see the resemblance between this wild root and the cultivated varieties it has spawned.  In fact, this is what cultivated carrot varieties look like when I try to grow them in my garden.  Extracting this much root pretty much puts an end to the carrot’s seed producing ability.  I hope to collect several pounds of these roots over the next few days.