| This small (1.5 acres) CRP field is in the far eastern end
of the Conservancy and remained fallow until 2004, when it was
treated with herbicide in advance of planting it to prairie.
It was treated twice in 2004 and twice more in 2005, and was
then virtually devoid of plants.
It was planted with a dry-mesic prairie mix on top of a light
snow cover in December 2005.
In the first growing season primarily annual weeds were present
(Erigeron philadelphicum, Tancetum vulagare,
Potentilla argentea, and Oxalis stricta),
although there was a few patches of lupine (Lupinus perennis),
evening primrose (Oenothera biennis), great blue
lobelia (Lobelia siphilitica), and black-eyed susan
(Rudbeckia hirta) in flower. A large amount of bird’s
foot trefoil (Lotus corniculata), an exotic agricultural
crop plant, appeared in the middle part of the field. The
origin of this infestation is unclear, but this same weed
is found in our other former agricultural fields. Each trefoil
plant was dug and removed.
The whole prairie was mowed in early September to remove
the annual weeds and to reduce the seed load of undesirable
species.
In the second growing season, more prairie species were seen,
either in flower or in the vegetative state. These included
Rudbeckia hirta, Baptisia alba, Lupine
perennis, Penstemon digitalis, Erirgeron
philadelphicus, Asclepias syriaca, Arnoglossum
atriplicifolia (flowering), Cirsium discolor, Achillea
milleflorum, Monarda fistulosum, Bromus kalmii (flowering),
Gaura biennis (flowering), Rudbeckia triloba
(flowering), Elymus virginiana (flowering),
Solidago nemoralis (flowering), Aster pilosus
(flowering), Aster laevis (flowering), Aster
oblongifolius (flowering), and Aster nova-angliae
(flowering).
However, as the photo below shows, the main flowering plant
during mid-summer was daisy fleabane (Erigeron strigosus).
Since this annual weed is native and does not persist it was
allowed to remain.
In addition, there were many undesirable plants, including
more bird’s foot trefoil (removed by digging), oxeye daisy,
tall lettuce, timothy, orchard grass, and bladderwort (flowering).
By early August of the second growing season there was a
large amount of Queen Anne’s lace (Daucus carota)
in flower in parts of the prairie. These areas were mowed
to keep them from setting seed.
A survey of the prairie showed a large species diversity
of prairie plants, including lots of Indian grass (Sorghastrum
nutans) and little blue stem (Schizachyrium scoparium).
At the beginning of the third growing season, a large amount
cool season grasses, primarily smooth brome, had developed.
Since there were no prairie (warm season) plants up yet, the
whole prairie was sprayed with glyphosate by the local agricultural
cooperative (see photo below). This spraying was very effective.
However, prairie plants had not developed yet when the spraying
was done so that they were unaffected. (Unit 21, to the right,
had been burned the day before the spraying was carried out.)
Despite the extensive control of bird’s foot trefoil in the first and second
growing seasons, there was still a major infestation in the
third growing season. Because most of the plants were well
separated from the “good” plants, herbicide was used to control
the trefoil. The herbicide of choice was clopryalid (trade
name Transline), which is active against all broadleaved species
but is especially effective against legumes. It took one person
a whole day to seek out and spray all the bird’s foot trefoil
plants. The spraying was very effective, and greatly reduced the amount of this nasty plant.
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Patches
of bird's foot trefoil in the Ridge Prairie. Because all
of the cool-season grass had been killed by the earlier
spraying, these patches were easy to spot. All were sprayed
with clopyralid (Transline). |
By mid June the Ridge Prairie was starting to look quite
good. A large number of prairie plants could be identified
at the vegetative stage, including a lot of compass plant,
white wild indigo, prairie dock, black-eyed susan, sky-blue
aster, etc. etc. The photo below shows how the Ridge Prairie
looked at this season. None of the green vegetation was from
cool-season grasses.
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The photo below shows the Ridge Prairie
as it appeared in early August 2008. A plant survey
recorded over 50 species of prairie plants, including
those still in the vegetative stage, some in flower,
and others past flowering and setting seed. The only
invasive plant was scattered Queen Anne's lace, but
this was removed a week later by the intern crew plus
several volunteers. |
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More simplified birds-foot trefoil control
Once the main birds foot trefoil infestation had been eliminated with Transline, it was possible to use a simpler control method on the occasional plants that appeared in subsequent years.
We have use an herbicide mixture formulated for basal bark work. This is 20% Garlon 4 diluted in bark oil. It turns out that spraying with this mixture at the bases of herbaceous plants will kill the whole plant, and with care the adjacent native species are unaffected since the herbicide is confined to just a narrow "spritz" area. This technique works beautifully for legumes such as alfalfa, multi-stemmed sweet clover, and birds foot trefoil. (It also works for other herbaceous weeds such as mullein and burdock.)
The technique is to grab some of the individual stems and lift them so that the center of the colony can be found. A few spritzes in the center is all that it takes to eliminate the whole plant. The photo above shows a dead birds foot plant adjacent to a thriving colony of black-eyed Susan. |
Spring 2012 burn of the Ridge Prairie and adjacent East Basin |
Although small, this prairie is attractive and
interesting. It is adjacent to the East Basin, now mostly restored. These two prairies are now burned together (see photo below) and for most purposes have almost
merged together.
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