Bindweeds

We have discovered two types of bindweed in our plantings – Field bindweed (Convolvus arvensis) and Hedge bindweed (Calystegia sepium). This isn’t good news when some researchers have called Field bindweed the 12th and the 10th “worst weed in the world”. (Pfirter, Mitich) Field bindweed has the status of a serious weed in 14 countries and a problem weed in 19 countries. Both plants have the ability to vine up other plants as they grow; making it difficult to control without collateral damage.

These bindweeds have been a problem in 2 of the 5 plantings that we have. Why it skipped three of them, I don’t understand, but am certainly glad for it. We also find it in 1 of the 3 propagation gardens.

Field bindweed has had a bad reputation since it was first introduced. Its introduction was either Montana in 1739 or California in 1884. In 1890, it was called “the most dreaded of the perennial weeds.” (Mitich) Interestingly, there are 84 known names for field bindweed; I know I have a few that I call it!!! Linnaeus named it in 1753. The botanical name is a “combination of Latin meaning ‘to roll together’ or ‘to entwine’ and ‘of the field.’” (Jacobs) Field bindweed is native to the Mediterranean and first described by Pedanius Discorides, a Greek medical herbalist. (Mitich)

Sadly, with all the negativity surrounding these plants, field bindweed is still around and used by gardeners as an ornamental. Pretty remarkable that the Morning Glory would be legal to plant today knowing its history and its ecology.

 

Field Bindweed Facts

  • A vining perennial that can grow from seeds, roots, or rhizomes
  • Root system is both vertical and horizontal.
  • Vertical roots can reach 20-30’ and horizontal roots are found in the top 2’ of soil. The horizontal roots will eventually turn and move vertically. (Jacobs, Mitich, Wright et al, Graham)
  • A single plant can create a 10-20’ radiating spread in one growing season.
  • Roots can bud, meaning that root pieces laying on the ground can propagate; even those as small as 5mm. Wright found that buds can be produced with roots found 14’ underground.
  • Food reserves in the roots allow the plant to survive underground for more than 3 years without replenishment.
  • Root nutrients are lowest in May before it begins growing.
  • Flowers last for only 1 day and are pollinated by Halictidae, honeybees, bumblebees, butterflies, and moths
  • Seeds can be viable for up to 60 years; on average one plant can produce 550 seeds; and tests have shown 87-99% are viable. One test showed 62% were viable after 50 years when stored at room temperature. (Jacobs)
  • Drought tolerant
  • Prefers heavy clay soil
  • Not shade tolerant 
Field bindweed, invasives, Convolvus arvensis

Diagram of field bindweed root system

Field bindweed, invasives, Convolvus arvensis

This growth represents only a few days.

Field bindweed, invasives, Convolvus arvensis

A good look at the leaf shape and plant growth habit.

Field bindweed, invasives, Convolvus arvensis

This is how long the root is and it broke off when I pulled it. This is a plant that is merely days old.

Hedge Bindweed Facts

  • A vining perennial
  • Native to eastern U.S. but considered a noxious weed in many states; it’s also native to Eurasia.
  • Stems can reach up to 10’
  • Roots are shallow but can extend up to 10’
  • Spreads by seeds or rhizomes and forms clones
  • Is allelopathic – produces a chemical that prevents other plants from growing around them
  • Releases Calystegines which can be poisonous to arthropods and mammals
  • Adapts to full sun or partial shade as well as a variety of soil conditions

 

Hedge bindweed, invasives, Calystegia sepium

The rosette of Calystegia sepium.

Hedge bindweed, invasives, Calystegia sepium

The root system of the rosette. Shows that it can be easily pulled in this early stage.

Hedge bindweed, invasives, Calystegia sepium, Convolvus arvensis

How the bindweeds grow together and form a ground cover that does not allow other for plants.

Control Techniques

Mowing is not the answer for the bindweeds; they are too low growing for it be effective. Smothering can be effective if done for several consecutive years and no vines find an opening to poke through.

One research document states that “there is currently no evidence of a successful biological control agent…” (Graham) I’m not sure when Graham wrote her paper but in 1997, Pfirter et al found 5 fungi were successful against C. sepium and 2 against C. arvensis; this research was not done in the U.S., so there could be more issues if these fungi are not native to America. Jacobs found a gall mite (Aceria malherbae) will attack the leaves and stems and a moth (Tyta luctuosa) will attack the flowers and leaves; neither of these are native to the U.S., so one could be introducing more problems than solutions. I am not a proponent of biological control so I did no further research on these.

Herbicides are effective but may need to be applied more than once and for more than one year. Some of the effective ones are triclopyr (Garlon 4®), glyphosate, metasulfuron (Escort® or Oust®) dicamba (Banvel® or Clarity®), fosamine (Krenite®), and 2,4-D. Wiese tested a variety of herbicides but found that glyphosate, fosamine, dicamba and 2,4-D were the most effective of those tested and effective at any time of the year but glyphosate had the best kill rate. They recommend using glyphosate at a rate of 7.3 lbs/2.5 acres. I have found that a 2% solution of 41% concentrate works well; that’s 2 2/3 oz of glyphosate to a gallon of water. Of course, this can differ slightly depending on the calibration of your sprayer.

Herbicide effectiveness lessens in years of drought. Field bindweed has a waxy surface, which is “three times greater” in drought conditions. (Jacobs) Using ammonium sulfate or Miracle Gro® at 2% by weight of will help the herbicide to penetrate the leaves. This is about 5 tablespoons of Miracle Gro® to 1 gallon of water.

Hedge bindweed, when in the rosette stage, can be hand pulled because of its shallow roots. If left to grow the roots will become too long for pulling. It can be controlled with herbicide in the same manner as field bindweed. 

Resources

Defago, G., H.U. Ammon, L. Cagan, B. Draeger, M.P. Greaves, D. Guntli, D. Hoeke, L. Klime, J. Lawrie, Y. Moenne-loccozi, B. Nicolet, H.A. Pfirteri, R. Tabacchi, and P. Toth. 2001. Towards the biocontrol of bindweeds with a microherbicide. BioControl 46: 157–173.

Graham, Jessica and Wayne S. Johnson. Managing Field Bindweed. University of Nevada Cooperative Extension Fact sheet 04-48.

Jacobs, Jim. 2007. Ecology and management of field bindweed. NRCS-Montana, Invasive Species Technical Note No. MT-9.

Mitich, Larry W. 1991. Field Bindweed. Weed Technology 5: 913-915.

Pfirter, Hanspeter A., Hans-Ulrich Ammon, Daniel Guntli, Michael P. Greaves, Genevieve Defago. 1997. Towards the management of field bindweed and hedge bindweed with fungal pathogens and cover crops. Integrated Pest Management Reviews 2: 61-69.

Swan, D.G. and R. J. Chancellor. 1976. Regenerative capacity of field bindweed roots. Weed Science 24(3): 306-308.

USDA Forest Service. Field Bindweed. Weed of the Week 02-08-06.

Wiese, Allen F. and Dwane E. Lavake. 1985. Control of field bindweed (Convolvulus arvensis) with postemergence herbicides. Weed Science 34: 77-80.

Wright, S.D, C.L. Elmore, D.W. Cudney. Oct 2011. Field Bindweed. University of California Agriculture and Natural Resources Pest Notes Publication 7462.




Going “au naturale”

What is ecological restoration? Some define it as returning the land to pre-settlement conditions, which in Wisconsin is pre-1830. Some define it as unnecessary work because they believe that “nature knows best” and to just let “nature take its course.” If we are to preserve the biodiversity that remains on our planet, we need to expand our definition beyond these archaic and fantastical notions. Perhaps a better definition would be creating habitat that is useable and functional so that a diversity of biota are able to thrive.

Habitat loss is not due only to development and farming. Much of the loss is due to alien plant species going unchecked and replacing the natives. This spread of non-native plants is the reason that “going au naturale” is very damaging and until this is reversed, it’s also unrealistic, which this article will address. 

A place in the woods where the invasives and weeds have taken over.

A place in the woods where the invasives and weeds have taken over.

A place in the woods where the invasives have been removed and the native plants are thriving.

Unlike the above photo where “nature is allowed to take its course,” this photo shows a place in the woods where the invasives have been removed and the native plants are thriving. In today’s world, landscapes much be managed if they are to be valuable for our wildlife.

Nearly every living being on this earth owes its existence to plants. Plants are the only means of converting the sun’s energy into nutrition, which is the life source to many animals. Often those animals will eat only specific plants which means for a diversity of animals to exist, a diversity of native plants need to exist and each plant must contribute to that ecosystem. For an alien to be considered a native, it must provide the same ecological services as it does in its home land; this process of naturalizing takes hundreds and hundreds of years. The non-native plants that are replacing our natives are not palatable to our native insects. The consequences of this radiate and compound, negatively affecting the diversity of life.

If we look at just insects, 90% of our plant-eating insects are specialists eating only one or two genera or species of plants. The complex chemical interactions between plants and insects don’t allow for insects to easily change to another host plant; it takes hundreds of years for this evolution to occur. As one example, a common reed, Phragmites australis, was introduced over 300 years ago into the US. In this vast amount of time, it only supports 5 species in the US, whereas it supports 170 species in its native region. (Tallamy, 285) There is no lack of these examples in the literature. One invasive that has displaced a great number of natives is Reed Canary Grass ( Phalaris arundinacea). It has no nutritional or habitat value to birds, insects, or mammals and it spreads rapidly.

Sadly, there are natives that invade and alter habitats as well. Boxelder trees (Acer negundo) and Red maples (Acer rubrum) are good examples. They invade prairies and woods where management activities have been excluded. They crowd out the other native species, change the composition of the habitat, and can create a monoculture. Anything that creates a monoculture decreases diversity and native or not, that isn’t a good thing for the rest of earth’s inhabitants.

There are many ways that non-natives alter the ecosystem. Er, uh…should we say a diversity of ways? Yes, I know…Ugh! We’ve briefly touched on their effects on insects and how they push out the native plants. They also can hybridize with natives, thereby changing the native gene pool. They alter fire effects making management with prescribed burns less predictable. They deplete nutrients and water available for other plants; they change the soil biota making that ecosystem less hospitable for the natives; they degrade wildlife forage; and their encroachment increases competitive pressure on endangered and threatened species.

The mistaken belief that the non-native berry bushes such as Honeysuckle and Oriental bittersweet are OK because birds eat the berries needs a closer look. Berries support birds after they have raised their young. Berries are not what the babies eat in order to develop and mature, insects are; 96% of all terrestrial birds in North America raise their babies on insects. When the insects aren’t plump, healthy, and numerous, neither are the birds. There is much literature linking bird health to the quality and quantity of insects they eat.

It is often difficult to “see” the negative effects of non-natives but that does not diminish their harmful consequences and the domino effect they have on diversity. As the quantity of non-native plants take over an area, the quantity of native insects, birds, reptiles, amphibians, and mammals are impacted. Many of us would never know if 100 or 1000 species of insects were no longer on our land. For some, it might take years to notice the loss of several birds.

Allowing invasives to crowd out natives is not how nature was intended to work and expecting that nature can change the direction of this negative multiplier effect is a fantasy. On a positive note, of all the reasons that our habitats are being destroyed, removing and controlling non-natives is the one where a single individual can make a huge difference in a short amount of time.

Resources

Tallamy, Douglas W. 2007. Bringing Nature Home. Portland, Ore: TimberPress.




Queen Anne’s Lace

It seems that Queen Anne’s lace (Daucus carota) (QAL) is blooming early this year. Maybe with the wet spring, it got a head start, too. Either way, Jim and I have spent several hours a day for several days pulling this aggressive, weedy, non-native plant.

Also known as Wild Carrot, QAL, produces copious amount of seed, which is part of its success in taking over areas where it is not controlled. This plant came to the US from Europe and is the predecessor to our cultivated carrots. When you pull it, the root has a distinct carrot aroma. It provides some medicinal qualities for humans, which is probably the reason it was brought to America. 

It’s hard to take a photo of the whole plant because they are “airy” and the green just blends in with the surroundings.

It’s hard to take a photo of the whole plant because they are “airy” and the green just blends in with the surroundings.
Each little white flower is part of this whole flower head.

Each little white flower is part of this whole flower head.

the whole plant because they are “airy” and the green just blends in with the surroundings.[/caption]

Each little white flower is part of this whole flower head.

This is what it looks like when the flowers start to set seed. They curl into a ball and each of those little white flowers develops into a seed. You can see how prolific a seed producer one plant can be.

I have found pulling it with the assistance of a Parsnip Predator to be the best way to remove it from a prairie or areas of patchy QAL growth. It’s a biennial so once it flowers, that plant has spent its life. We wait until it is just about ready to set seed, then we pull it. If you cut it before that, it continues growing and getting bushier and bushier around the base, shading out any native seedlings that may be wanting to grow. If we were trying to eradicate from a field where it had become prevalent, I would mow it for several years after it bloomed rather than use the Parsnip Predator. When working with a large scale infestation, mowing is merely a triage move so you are not adding more seed to the seedbank.  So, to handle a large scale project, chunk off pieces to herbicide or pull, and mow the rest to keep it from going to seed. I’ve found the herbicide, Opensight, to be VERY effective in killing these plants.

This is an example of how bushy the QAL can be when cut before it blooms. It also supports a few more flower heads when it becomes this bushy.

The base of the stem moves down to a single root so using a Parsnip Predator to sever that root is fairly easy. Even the bushy plants only have a single root.

The seed bank is reported to persist for 2-5 years. We had quite a bit of QAL on the edges of the 5-Acre Prairie the first 2 years after it was planted. I pulled these and now have only a smattering here and there. Although not a scientific study, it does demonstrate that this plant can be removed and controlled from native areas.

While QAL provides a cover for wildlife, it has little value for wildlife beyond that. I have seen pollinators searching on the flowers, but this alone is not reason enough to maintain this plant. A diversity of native plants that bloom throughout the growing season is much more helpful to pollinators than the short time QAL is blooming. And the native plants provide so much more to wildlife; they serve as food, habitat, reproductive hosts, and provide cover.