Zizia aureus fall regrowth

Right now Zizia aureus (golden Alexanders) is showing lush growth throughout our open savannas. Fall regrowth like this is fairly common.

Fall regrowth is an interesting ecological phenomenon. I assume this works as follows:

• Since Zizia is a species that shows up early in the spring, it does best in cooler weather.
• It flowers, sets seed, and dies back by early August, but the root stock is still alive.
• When the weather turns cool again, new buds grow and form leaves.
• The leaves photosynthesize and translocate carbohydrates to the roots.
• When winter comes, the above-ground portions die back, but the roots remain alive.
• Spring growth starts early, as soon as the soil starts to warm up. The energy in the roots from the fall process gives the plants a head start. 
• Flower buds start to show in early April.
• The whole cycle continues through another year.

There are lots of "bad" plants that exhibit fall regrowth, and probably carry out this same cycle. One of the most serious is garlic mustard, but others are reed canary grass, bluegrass, motherwort, and mullein.

Incidentally, right now is an excellent time to spray any bad plants using glyphosate. Most of the native plants have senesced and will not be affected, whereas the green leaves of the weeds will absorb the herbicide and translocate it to the roots. The only problem is to avoid spraying any good plans such as Zizia.

Mushrooms on the prairie

The heavy late fall rains last week brought on an enormous flush of mushrooms on Toby’s Prairie, and to a lesser extent on the Pocket Prairie. Amanda and Susan discovered them while seed collecting. The species was Agaricus campestris,  common name “meadow mushroom”, which is closely related to the cultivated species (A. bisporus).

Among other things, the meadow mushroom is known for forming circles called “fairy rings”on lawns, golf courses, or meadows. Despite the literature, there is nothing mystical or mythical about a fairy ring. It is just a growth phenomenon. The mushroom mycelium grows out from a single center (probably starting from a single spore), growing on the rich organic matter of the lawn or prairie.  It may grow for quite a while in this vegetative state, but generally in response to a good rain (we had 1.5 inches last week) it undergoes morphogenesis and forms fruiting bodies at the periphery of the ring.

Part of a "line" of mushrooms, a fragment of a fairy ri

In a tallgrass prairie a fairy ring is not as photogenic as it is on a lawn. Also, sometimes a complete ring is not formed, only parts of a ring (arcs), and this is what we have in Toby’s Prairie.  The photo here shows an example.

Although we see occasional mushrooms in our prairies, this is the first time we have seen such an enormous flush. The mushroom is a saprophyte, which means it grows on dead plant material. Because of  the impact of the drought, there is a lot of mushroom food on the surface of the soil, and fruiting was brought about by the good fall rains.

This mushroom should have no detrimental effect on the prairie. The extensive mycelium that it forms on the surface of the soil will eventually die and become incorporated into the rich organic humus that a prairie makes.

Yes, this species is edible!

Herbicide spritz technique for control of herbaceous invasive plants

The herbicide spritz technique is suitable for precise control of broad-leaved herbaceous invasive plants, especially clonal species such as Canada goldenrod and perennial sunflowers. This technique makes use of a high concentration of an oil-soluble herbicide (such as Garlon 4) diluted to 20% with a penetrating bark oil. Only a few drops of herbicide on the meristem or one or two leaves is all that is necessary. The herbicide quickly penetrates the leaf and spreads throughout the plant. Response is very rapid.

During the mid-summer growing season, the sprayed plant usually shows a discoloration or wilting response in a few hours. Within several days even leaves on that stem that have not been sprayed begin to respond, and within a week the whole plant is moribund. If all stems of the clone are spritzed, then the complete clone is eradicated and does not return the following year.

Although labor intensive, this technique is very selective and hence suitable for control of invasive perennial weeds in planted or remnant prairies and savannas.

The herbicide mix used is identical to that used for basal bark treatment of woody plants. Hence, both woody and herbaceous weeds can be dealt with on the same pass through a natural area. 

Dense clone of invasive sunflower

Single stem that has been spritzed (red dye used as marker).

During the early summer growing season, response is very rapid. These plants had been spritzed the day before. Note discoloration and death of leaves.

Clone that had been spritzed two weeks before.

 Canada goldenrod stems that had been spritzed a few days before. Only one or two leaves were spritzed on each stem. A "wipe" technique can also be used with a sponge or glove applicator. Care must be taken to ensure that each stem of the clone is treated.

Sumac eradication

Sumac can be eradicated but requires special attention to its manner of growth and reproduction. Although it is native, sumac is highly invasive. Allowed to proceed unchecked, it is able to take over a prairie or savanna natural area. The shade under a sumac patch can be enough to suppress virtually all native vegetation.  If the character of a natural area is to be maintained, control of sumac is essential.

A large sumac clone that has established itself in what was once a large prairie

The shade from this dense sumac clone has suppressed all native species

The techniques described here are based on studies and observations done over the past five years on both large and small sumac clones.


Sumac Ecology Sumac is a woody plant that has the potential for forming large clones (thickets). It spreads rapidly and is the single most-important woody invasive plant at many sites. It spreads by rhizomes which form complex underground root systems. In addition to their role in increasing the size of the clone, sumac rhizomes are capable of sending up myriads of new shoots, called “root suckers.”

Sumac is very sensitive to herbicides such as triclopyr (Garlon 3A and 4), so that existing stems can be killed by cutting and treating, or by basal bark treatment. However, although herbicide treatment will kill above-ground stems, rhizomes and the buds that turn into root suckers usually escape treatment. If sumac is to be eradicated, these below-ground parts of the clone must be dealt with. A principal part of the present post focuses on how root suckers can be eradicated.


Herbicide sensitivity Sumac is sensitive to a variety of herbicides that are active against broad-leaved plants. One of the best is triclopyr (Garlon).There are two chemical forms: Garlon 3A is the water-soluble form and is recommended for foliar spraying (used at 3% concentration) whereas Garlon 4 Ultra is the oil-soluble form and is recommended for cut stem and basal bark treatments (used at 20% in bark oil). (There are “generic” versions of triclopyr that are less expensive and but are equally effective.)

Mowing a large sumac clone that had invaded a prairie remnant

Mowing is often recommended as a means of controlling sumac. What happens when sumac stems are cut? Along the length of each sumac stem are buds that remain dormant as long as the top part of the stem is alive. However, if the stem is cut, one or more of these dormant buds are released and grow. The photo to left shows the response of a sumac stem to cutting. Thus, it is not possible to eradicate a sumac clone by mowing, although mowing can work well as part of an integrated management system.



Fire is often recommended as a way of controlling sumac. What happens when sumac stems are burned? The terminal growing shoot and all the buds along the sumac stem are generally top-killed by fire. However, each sumac stem has one or more dormant buds present at its base. Since these buds are below the soil surface, they are not harmed by fire. Therefore, when a stem is top-killed by fire, a dormant bud of that stem becomes activated and sends up a new shoot. Thus, the sumac plant resprouts vigorously when killed by burning. The photo to the right shows a new shoot just starting from the base of a stem that had been top-killed by fire.

A prescribed burn will generally top-kill all stems of a sumac clone

What happens when sumac stems are treated with herbicide? When a sumac stem is treated with triclopyr, either with a foliar spray of Garlon 3A, or a cut stem or basal bark application with Garlon 4 in oil, the stem and all its above-ground and below-ground buds are killed.

The stems of this small sumac clone were treated with Garlon 4 by basal bark. Within a few days the leaves exhibited damage by turning red and within several weeks the whole plant was dead.

Herbicide-treated sumac plants in a short-grass prairie

Root suckering, an important property of sumac Although herbicide will kill the sumac stem, the network of rhizomes associated with this stem are not affected. Dormant buds will be released and send up vigorous new shoots. These new shoots are called root suckers. (Many clonal plant species produce root suckers.)

Thus, although the above-ground sumac plant can be killed by either fire or herbicide treatment, root suckers are formed from buds within the extensive rhizome complex. In fact, more root suckers may be formed than there were in the existing above-ground stems. Therefore, killing of root suckers is essential if the clone is to be eradicated.

Typical root sucker, arising from the hidden underground rhizome system.

Note that there is no sumac stem nearby.

How are root suckers eradicated? Whenever a sumac clone is treated in such a manner that its above-ground parts are killed, it must be monitored for the formation of root suckers and when they are found they must be killed with foliar Garlon (3% aqueous Garlon 3A). Each root sucker must be sought out and destroyed. Not all the root suckers appear at the same time. The timing of this search-and-destroy operation will depend on the growing conditions at the site, and must be done for at least three years.

Locating sumac clones Very large clones are easy to locate. Smaller clones are harder to find but should be given high priority since they have the potential of making larger clones. Since sumac leaves develop intense red color in the fall of the year, this red color can be used to look for sumac clones. Mark each clone, either with GPS or with a permanent marker (wooden stake, rebar, or other suitable marker). Each clone should be given an control number.

Any single sumac plants will not have formed a rhizome system yet. They should be herbicided immediately, using the basal bark technique. (The basal bark technique is effective twelve months of the year and can be used any time a sumac plant is found.)

Canvassing a short-grass prairie for isolated sumac plants

Eradicating a large sumac clone: an example.

Here is an example for southern Wisconsin (probably applicable to other nearby states). This work was done in a high-quality remnant prairie where sumac had become established. On August 1, 2009 the sumac stems of a clone were mowed with a Stihl brush cutter and all the cut material was hauled away. There were 202 cut stems, each of which was treated with 20% Garlon 4 diluted in bark oil. Treatment was a combined cut stem and basal bark.

Seven weeks after cutting and treating  the results were monitored. The Garlon 4 treatment of the cut stems was completely effective. Because it was late in the season, no root suckers formed, but they were anticipated for the following year.

In 2010, the next growing season, the plot was monitored frequently. Root suckers appeared throughout the season and by late summer 183 root suckers had been formed. Note that none of these root suckers arose from the original cut stems. As the tally was being carried out, each root sucker was sprayed with aqueous 3% Garlon 3A. This herbicide treatment was very effective and all root suckers were killed.

The following year (2011), the plot was monitored again and 25 new root suckers were present.  These new stems were treated with Garlon 3A.

In 2012, three years after the original procedure, no new root suckers were present. A summary of the results is shown in the graph.

Thus, in this study it was possible in three years to eradicate the sumac clone by cutting and treating followed by treatment each year of all new root suckers.

During the three years that this study was underway, the area of this sumac clone was not barren. Many good species moved in. A survey done at the end of the study revealed the following species: flowering spurge, showy sunflower, rosin weed, compass plant, spiderwort, prairie thimbleweed, bergamot, butterfly milkweed, rough blazing star, false boneset, lead plant, evening primrose, Indian grass, little bluestem, and solomon’s seal. Thus, the dense sumac monoculture was converted into a highly diverse prairie!

Follow this link for extended information on sumac ecology