Birdsfoot Trefoil
July 2001
We were assigned to the Big Woods Unit in April 2001. There were 2-3 foot diameter foliage mats which were single birdsfoot trefoil plants. We began spraying during that first growing season in 2001. We adopted a philosophy of accepting collateral damage as it was clear that interesting plants were guaranteed to vanish regardless of spraying or not spraying. In many instances we would resort to hand pulling birdsfoot trefoil in order to protect particularly interesting plants, e.g. Asclepias viridiflora. After 2010 when we learned that birdsfoot does not replenish root reserves until fall, ripping off the above ground foliage became a very attractive option. See later discussion. Hank always carries a parsnip spade which he uses to shield native species from overspray.
Birdsfoot trefoil continues to bloom and set seed until September, therefore it is especially important to spray until September. Although foliage remains green until at least mid–November, it is difficult to see and spray after August 1 when it is located in areas of tall grass such as Andropogan gerardii and Sorghastrum nutans.
In 2001, Hank began spraying yellow blooming birdsfoot trefoil. Our jeep is parked at the Old Ditch Crossing. The photo is taken from southeast corner of East Knob looking southeast across South Ditch to tree line at Wade Creek on Eight Oaks boundary. The vegetation in the foreground is brome and rubus. In front of the treeline are sectors 5 and 6 of Wade Bottoms with two trees in the middle of sector 6. (See the discussion of sectors in the paragraph just below the April 2011 photo below.) Trees at the far right are part of East Woods. The yellow spots between Hank and the bottom of the photo are birdsfoot trefoil blooms.
Birdsfoot trefoil continues to bloom and set seed until September, therefore it is especially important to spray until September. Although foliage remains green until at least mid–November, it is difficult to see and spray after August 1 when it is located in areas of tall grass such as Andropogan gerardii and Sorghastrum nutans.
In 2001, Hank began spraying yellow blooming birdsfoot trefoil. Our jeep is parked at the Old Ditch Crossing. The photo is taken from southeast corner of East Knob looking southeast across South Ditch to tree line at Wade Creek on Eight Oaks boundary. The vegetation in the foreground is brome and rubus. In front of the treeline are sectors 5 and 6 of Wade Bottoms with two trees in the middle of sector 6. (See the discussion of sectors in the paragraph just below the April 2011 photo below.) Trees at the far right are part of East Woods. The yellow spots between Hank and the bottom of the photo are birdsfoot trefoil blooms.
May 2006
The next photo was taken at the east end of Sedge Meadow looking west. Birdsfoot trefoil was extremely thick in the Sedge Meadow initially in 2001. The parts of the Sedge Meadow which have become very wet (See Ditch Section and Sedge Meadow Willow Section) no longer have birdsfoot trefoil at all. In Wade Bottoms where there is intermittently standing water, birdsfoot does not germinate until the areas dry out. There are lots of BFT plants in the area around Hank in the photo above, but the brome grass is too tall to see them.
April 2011
One of our management features which interests visitors is our flagging system. In order to meet our goal of no seed production by birdsfoot trefoil we had to be very methodical in sweeping the populated areas. Early on, Hank and Al Meier were laying out three parallel ropes and walking between them. This was tedious as they had to stop after covering the area bounded by the outer ropes and move two ropes forward. We switched to rows of flags. Wade Bottoms is divided into six sectors by placing five rows of north-south flags. The outside boundaries are marked by the 2-track to the Z bridge on the east and the Ditch on the west. There are three rows of flags in the photo. The yellow flags in the foreground are north of the 2-track dividing Aldo Leopold and Wade Bottoms. Its matching row of flags is not visible further west on Aldo Leopold. The white flags at the left of the photo are the boundary between Sector 1 and Sector 2 in Wade Bottoms. At the far right is part of the flag line between Sector 2 and Sector3. The flags are aligned across the field so by walking between two flags one is assured of sweeping a two or three foot wide path from east to west. You can also keep track of what area you have covered. It is much more efficient than a random walk through the area to be sprayed. The field between North Knob and the ditch (not shown) is divided into two parts by a row of flags. Dividing areas into sectors allows us to spray smaller, manageable areas which can be covered in a few hours.
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We sprayed birdsfoot trefoil west of the Ditch in 2001, 2002, 2003, 2004, and 2005, but did not record the amount used. In 2005 we started recording usage of the herbicide, Crossbow. See the charts below. We did not track herbicide usage in Wade Bottoms until 2008 and on Aldo until 2010. The charts above do not include Aldo data.
June 2009
We sprayed birdsfoot trefoil in 2006 west of the Ditch; there was significantly less birdsfoot that year if you believe the statistics that we used about half as many gallons of herbicide than was used in 2005. We also swept the Ditch scrape for Queen Anne’s lace, mullein and birdsfoot trefoil. (See Ditch Section for more details.) This included the east side of the Ditch all the way east to the north/south 2-track. We were encouraged....but wait until the monsoons arrive in 2008!
We sprayed birdsfoot trefoil in 2007. We used 3.5 gallons more Crossbow than in 2006. Late in the summer 2007, Al Meier “donated” the south six acres of the Dot/Doug Wade Unit to Big Woods. We named it Wade Bottoms. During the last sweep of 2007 we began including the western boundary area of Wade Bottoms in our birdsfoot trefoil sweeps. We also sprayed quite a bit on the west flank of Little Aldo. We were still checking the Ditch scrape for weeds and would randomly look at the western area of Wade Bottoms but found no birdsfoot trefoil at that point in time. We were convinced that we had turned the corner on birdsfoot trefoil and would see very little in the spring of 2008.
We sprayed birdsfoot trefoil in 2008 which is one of the wettest years on record for Illinois. Our herbicide usage overall tripled. See the charts above. We believe we had prevented any significant seed production in the years since 2001. The year 2008 produced ideal germination conditions for millions of seed in the seed bank. In some places a square foot would contain a hundred or more birdsfoot trefoil seedlings. Can you say “Carpet spraying; I love the smell of Crossbow in the morning”? Either we kill the birdsfoot trefoil (and some forbs) or it will kill all the prairie forbs. By 2008 Hank was primarily sweeping traditional Big Woods and Becky was covering Wade Bottoms and east of the North Ditch to the base of Little Aldo. BUMMER!! Surely 2009 will be better!
In 2009 we sprayed birdsfoot trefoil. We used more Crossbow than in 2008. See herbicide charts above. 2009 was as rainy as 2008. There was water flowing in the Ditch all year long. We believe this was our peak year for germination. That being true, then it was actually good to greatly reduce the seed bank in just these two years. All of that seed must have been produced in 2002 or earlier years. The birdsfoot trefoil plants we were spraying were obviously new plants so the seed bank is phenomenal. See Cody’s email at end of this section. By 2015 we should have a definitive answer about the birdsfoot trefoil seed in the seed bank.
Because we have been overseeding every year (see Seed Section for details) there are now lots of yellow flowers which aren’t birdsfoot trefoil so that one has to be careful about what you reflexively spray. Hank telephoned me to ask me to walk over from Wade Bottoms to see what he was NOT spraying, Liparis loeselii (see photo above). Becky is sure that she mindlessly sprayed quite a lot of Oxalis stricta and Medicago lupulina during the last ten years. Eventually the overseeding produced small Astragalus canadensis which require stopping and staring in order to determine they are not birdsfoot trefoil and should not be sprayed. Also Petalostemum candidum can look very much like BFT when it is small.
We sprayed birdsfoot trefoil in 2007. We used 3.5 gallons more Crossbow than in 2006. Late in the summer 2007, Al Meier “donated” the south six acres of the Dot/Doug Wade Unit to Big Woods. We named it Wade Bottoms. During the last sweep of 2007 we began including the western boundary area of Wade Bottoms in our birdsfoot trefoil sweeps. We also sprayed quite a bit on the west flank of Little Aldo. We were still checking the Ditch scrape for weeds and would randomly look at the western area of Wade Bottoms but found no birdsfoot trefoil at that point in time. We were convinced that we had turned the corner on birdsfoot trefoil and would see very little in the spring of 2008.
We sprayed birdsfoot trefoil in 2008 which is one of the wettest years on record for Illinois. Our herbicide usage overall tripled. See the charts above. We believe we had prevented any significant seed production in the years since 2001. The year 2008 produced ideal germination conditions for millions of seed in the seed bank. In some places a square foot would contain a hundred or more birdsfoot trefoil seedlings. Can you say “Carpet spraying; I love the smell of Crossbow in the morning”? Either we kill the birdsfoot trefoil (and some forbs) or it will kill all the prairie forbs. By 2008 Hank was primarily sweeping traditional Big Woods and Becky was covering Wade Bottoms and east of the North Ditch to the base of Little Aldo. BUMMER!! Surely 2009 will be better!
In 2009 we sprayed birdsfoot trefoil. We used more Crossbow than in 2008. See herbicide charts above. 2009 was as rainy as 2008. There was water flowing in the Ditch all year long. We believe this was our peak year for germination. That being true, then it was actually good to greatly reduce the seed bank in just these two years. All of that seed must have been produced in 2002 or earlier years. The birdsfoot trefoil plants we were spraying were obviously new plants so the seed bank is phenomenal. See Cody’s email at end of this section. By 2015 we should have a definitive answer about the birdsfoot trefoil seed in the seed bank.
Because we have been overseeding every year (see Seed Section for details) there are now lots of yellow flowers which aren’t birdsfoot trefoil so that one has to be careful about what you reflexively spray. Hank telephoned me to ask me to walk over from Wade Bottoms to see what he was NOT spraying, Liparis loeselii (see photo above). Becky is sure that she mindlessly sprayed quite a lot of Oxalis stricta and Medicago lupulina during the last ten years. Eventually the overseeding produced small Astragalus canadensis which require stopping and staring in order to determine they are not birdsfoot trefoil and should not be sprayed. Also Petalostemum candidum can look very much like BFT when it is small.
BFT plant sprayed with Transline
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BFT plant sprayed with Crossbow
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By the end of the second season of spraying it was well established in our plan that the bottom line was to allow no birdsfoot trefoil to set seed. This was probably realistically attainable beginning in 2005 after Becky retired and certainly after Hank retired in December 2007. In the years when we were only spraying birdsfoot trefoil a few days of a month, we would carry a plastic baggie, remove seed by hand and deposit them on the burnpile at the Headquarters Barn.
SUMMARY
2001 First year of herbiciding west of ditch.
2006 First year of herbiciding east of ditch including west side of Little Aldo.
2007 Significant decrease in population of birdsfoot trefoil.
2008 Birdsfoot trefoil population explosion. First year of herbiciding Wade Bottoms and south side of Little Aldo.
2009 Birdsfoot trefoil population explosion, part 2.
2010 Significant decrease in population of birdsfoot trefoil. First year of herbiciding east and north sides of Little Aldo.
2011 Significant decrease in population of birdsfoot trefoil. First year of herbiciding south side of Doug's Knob and north side of Aldo Leopold Knob.
It is important to know that 2006 and 2007 were dry years. 2008-2010 were exceptionally wet years. In the spring of 2008, there was almost continuous rain. There were literally tens of thousands of first year seedlings in places we saw zero plants at the end of 2007. In 2009, it was again very wet, but we might have seen only thousands of plants. The good news was that both years there were essentially only first year seedlings. 2010 continued as one of the wetter years on record in Illinois. Since the Big Woods Unit was burned in November 2009 we were able to begin spraying early in April 2010 but found few plants. We are optimistic that the seed bank is being exhausted. See herbicide usage for comparison of populations.
Wade Bottoms was broad leaf boom sprayed annually beginning some year before 2000. We overseeded the area (which was almost totally grass and BFT) in the fall of 2007. Birdsfoot trefoil germination is often next to a newly germinated prairie plant. It is likely soil moisture conditions in a small area are favorable to all seeds. Expect collateral damage. We can collect and plant more seed.
Germination increases with heat. Once it warmed up at the end of May 2010, we saw more germination than we would like but nothing that was comparable to 2008 and 2009. Refer back to herbicide usage data.
Birdsfoot trefoil seed appear to move in water. Wade Bottoms is south of the Aldo Leopold Knob complex which has a well established population of birdsfoot trefoil. Long time volunteer Ann Haverstock commented to us that Aldo is the first place at Nachusa Grasslands anyone noticed birdsfoot trefoil. The western half of the Aldo complex drains onto Big Woods including the Wade Bottoms area. The strip of ground immediately south of the 2-track separating Aldo Leopold and Wade Bottoms contained so much more birdsfoot trefoil than other areas of Wade Bottoms that in 2010 we began also spraying the drainage between Aldo and Little Aldo and in 2011 added as much more of the area north and east of Wade Bottoms as we could find time to sweep.
Birdsfoot trefoil does not like obligate areas. In 2010 there were large flat areas of Wade Bottoms with standing water; this is in addition to the Lake Aldo area which was spring ephemeral until the 2008 rains began. Lake Aldo retained water most of the time through 2011. In 2010 there were perhaps 4 weeks (not continuous) when Lake Aldo was dry. In the other areas of standing water birdsfoot trefoil did not appear until after the water was gone. After Lake Aldo dried up in the drought of 2012, BFT has made a major comeback.
The prairie contains a lot of busy burrowers. They move around huge quantities of dirt. The mound in front of the burrow entrance is a prime location for new birdsfoot trefoil plants. This makes me paranoid. Which critters are actually eating this seed? How much do they have stored which is eventually going to resurface and germinate? Are there insects storing it and eating only some of it?
We are spraying an area of 15-20 acres. We divide it into sections using equally spaced utility marker-style flags. This allows us to know what area we have completed and to cover the entire area without skipping spots. We have used both backpack sprayers and hand spray bottles. To avoid respraying plants we have already treated, we use dye in the herbicide mix so there is no doubt that a plant has already been sprayed. The first year after the ditch contouring occurred was dry. While sweeping the disturbed area (where the spoil was bulldozed back into the east ditch) for Daucus carota, Verbascum thapsus, and Pastinaca sativa, it was possible to carry only a spray bottle and also kill any birdsfoot trefoil. During the growing season where ever we are on the preserve, we try to always have a hand spray bottle with us for random plants.
Crossbow is more effective for us than Transline. As a test, we flagged and sprayed 4 plants with Crossbow and 4 plants with Transline. After 2 weeks the Transline plants were NOT clearly dead. Crossbow sprayed plants visibly wilt within hours and are crispy dead within 48 hours. Since we often resweep an area in less than two weeks, it is important to be able to tell if a plant is dead or alive. In the left photo above, with a “T” on the flag, the BFT plant was sprayed transline. The right photo with a “C” on the flag was sprayed with crossbow. Both plants were sprayed at the same time and the photos taken at the same time several days later. The plant sprayed with crossbow is clearly dead.
SUMMARY
2001 First year of herbiciding west of ditch.
2006 First year of herbiciding east of ditch including west side of Little Aldo.
2007 Significant decrease in population of birdsfoot trefoil.
2008 Birdsfoot trefoil population explosion. First year of herbiciding Wade Bottoms and south side of Little Aldo.
2009 Birdsfoot trefoil population explosion, part 2.
2010 Significant decrease in population of birdsfoot trefoil. First year of herbiciding east and north sides of Little Aldo.
2011 Significant decrease in population of birdsfoot trefoil. First year of herbiciding south side of Doug's Knob and north side of Aldo Leopold Knob.
It is important to know that 2006 and 2007 were dry years. 2008-2010 were exceptionally wet years. In the spring of 2008, there was almost continuous rain. There were literally tens of thousands of first year seedlings in places we saw zero plants at the end of 2007. In 2009, it was again very wet, but we might have seen only thousands of plants. The good news was that both years there were essentially only first year seedlings. 2010 continued as one of the wetter years on record in Illinois. Since the Big Woods Unit was burned in November 2009 we were able to begin spraying early in April 2010 but found few plants. We are optimistic that the seed bank is being exhausted. See herbicide usage for comparison of populations.
Wade Bottoms was broad leaf boom sprayed annually beginning some year before 2000. We overseeded the area (which was almost totally grass and BFT) in the fall of 2007. Birdsfoot trefoil germination is often next to a newly germinated prairie plant. It is likely soil moisture conditions in a small area are favorable to all seeds. Expect collateral damage. We can collect and plant more seed.
Germination increases with heat. Once it warmed up at the end of May 2010, we saw more germination than we would like but nothing that was comparable to 2008 and 2009. Refer back to herbicide usage data.
Birdsfoot trefoil seed appear to move in water. Wade Bottoms is south of the Aldo Leopold Knob complex which has a well established population of birdsfoot trefoil. Long time volunteer Ann Haverstock commented to us that Aldo is the first place at Nachusa Grasslands anyone noticed birdsfoot trefoil. The western half of the Aldo complex drains onto Big Woods including the Wade Bottoms area. The strip of ground immediately south of the 2-track separating Aldo Leopold and Wade Bottoms contained so much more birdsfoot trefoil than other areas of Wade Bottoms that in 2010 we began also spraying the drainage between Aldo and Little Aldo and in 2011 added as much more of the area north and east of Wade Bottoms as we could find time to sweep.
Birdsfoot trefoil does not like obligate areas. In 2010 there were large flat areas of Wade Bottoms with standing water; this is in addition to the Lake Aldo area which was spring ephemeral until the 2008 rains began. Lake Aldo retained water most of the time through 2011. In 2010 there were perhaps 4 weeks (not continuous) when Lake Aldo was dry. In the other areas of standing water birdsfoot trefoil did not appear until after the water was gone. After Lake Aldo dried up in the drought of 2012, BFT has made a major comeback.
The prairie contains a lot of busy burrowers. They move around huge quantities of dirt. The mound in front of the burrow entrance is a prime location for new birdsfoot trefoil plants. This makes me paranoid. Which critters are actually eating this seed? How much do they have stored which is eventually going to resurface and germinate? Are there insects storing it and eating only some of it?
We are spraying an area of 15-20 acres. We divide it into sections using equally spaced utility marker-style flags. This allows us to know what area we have completed and to cover the entire area without skipping spots. We have used both backpack sprayers and hand spray bottles. To avoid respraying plants we have already treated, we use dye in the herbicide mix so there is no doubt that a plant has already been sprayed. The first year after the ditch contouring occurred was dry. While sweeping the disturbed area (where the spoil was bulldozed back into the east ditch) for Daucus carota, Verbascum thapsus, and Pastinaca sativa, it was possible to carry only a spray bottle and also kill any birdsfoot trefoil. During the growing season where ever we are on the preserve, we try to always have a hand spray bottle with us for random plants.
Crossbow is more effective for us than Transline. As a test, we flagged and sprayed 4 plants with Crossbow and 4 plants with Transline. After 2 weeks the Transline plants were NOT clearly dead. Crossbow sprayed plants visibly wilt within hours and are crispy dead within 48 hours. Since we often resweep an area in less than two weeks, it is important to be able to tell if a plant is dead or alive. In the left photo above, with a “T” on the flag, the BFT plant was sprayed transline. The right photo with a “C” on the flag was sprayed with crossbow. Both plants were sprayed at the same time and the photos taken at the same time several days later. The plant sprayed with crossbow is clearly dead.
Entire plant sprayed
On some species, it is only necessary to herbicide the growing center of the plant to kill it. This is may not be true of birdsfoot trefoil! It grows long tendrils from a center hub ultimately creating large mats. If any stem is not sprayed, that stem remains alive and the plant can recover and continue to grow. This is especially true where Transline is boom sprayed without penetrating the surrounding foliage to the base of the birdsfoot trefoil plant. And in resweeping an area weeks or a month later, it is possible to see crispy plants with a healthy single stem flourishing. At some point, someone questioned whether or not Crossbow was actually killing the plants or just top-killing plants we were spraying. Hank marked and sprayed 18 substantial plants. He checked them for the next year and found no plants alive.
In addition we decided to flag demonstration plants for various styles of spraying. The cases chosen were:
Plants were sprayed April 27, 2012. These four photos were taken 16 days later on May 12, 2012. In each photo you should locate the central hub of the plant. A BFT plant which is covered entirely with crossbow herbicide will normally show no green leaves after 2 days.
In addition we decided to flag demonstration plants for various styles of spraying. The cases chosen were:
- Spray the entire plant.
- Spray half of a birdsfoot trefoil plant — a piece of cardboard was placed over half of the plant. The other half was sprayed.
- Spray only the center of a plant — only the center 2" of the plant was sprayed.
- Spray only the tips of the tendrils of a plant — a 4" diameter piece of cardboard was placed over the center so all of the plant except the center 4" was sprayed.
Plants were sprayed April 27, 2012. These four photos were taken 16 days later on May 12, 2012. In each photo you should locate the central hub of the plant. A BFT plant which is covered entirely with crossbow herbicide will normally show no green leaves after 2 days.
Half the plant was sprayed
Center of plant was sprayed
Tips of plant were sprayed
Conclusion: BFT plants must be covered entirely to be sure that the plant is killed.
A fall burn is significantly helpful for controlling birdsfoot trefoil. The ground warms up earlier the next spring and birdsfoot trefoil begins growing earlier. It is easier to see birdsfoot trefoil with the surrounding vegetation burned off. It requires less herbicide to kill small plants. There is less collateral damage as many native plants are not yet growing.
Mostly people do not have a lot of experience with this plant. A single seed can be moved into an area, germinate, bloom and produce seed for many years before it is perceived as a problem plant. In a very few years the seed bank might contain thousands of seed even though the plant population is not yet huge. See information from the internet below. Our experience suggests that boom spraying once or twice in a growing season is ineffective in eradicating this plant.
Pre-emergent herbicide may be an answer in highly degraded areas.
It is not completely clear how this plant spreads!
We consistently see isolated plants randomly occur far from the areas with established populations. We don’t believe that deer are a major vector as we have not seen an increase in birdsfoot trefoil plants along deer trails. We have become convinced that the two most likely vectors for spreading BFT are boots and vehicle tires.
The isolated plants that we encounter are in high foot traffic areas and/or close to vehicle routes. Birdsfoot trefoil plants are rarely seen in rubus patches! The heaviest infestations on Little Aldo occurred in areas where the tractor had been driven for boom praying. This could be a chicken or egg question though. The Aldo Knobs are very high foot traffic areas due to the desirable seed to be picked there. Only isolated plants occur on the tops of those knobs with boots being the most likely transmission source. Anyone walking around in an area with a BFT problem should seriously think about NOT subsequently walking in other locations.
Interesting Birdsfoot Trefoil Information from the Internet
Birdsfoot trefoil email 6/23/2010 – from Cody Considine
The following is interesting info on BFT Cody found quickly on the web. All information to the end of this section is from the internet.
A couple things stuck out:
http://extension.missouri.edu/publications/DisplayPub.aspx?P=G4640
Cody Considine says, “Pre–emergent herbicide will hopefully be the answer. I would still like to recruit a Master’s student to do their thesis on this plant.“
Trefoil and alfalfa initiate their first spring growth from stored energy in their root systems. After the growth is removed, alfalfa will replenish its root reserve in about 35 to 45 days throughout the growing season. Trefoil is noticeably different; it does not replenish its root reserves until fall and must depend upon photosynthesis from its leaves to supply energy for all of its regrowth during the late spring and summer. After about the first of September, trefoil once again will attempt to build up its root reserves that have been depleted since the first spring growth.
Trefoil's different way of storing root reserves explains why summer stockpiling of large amounts of growth usually results in stand depletion following the removal of this growth by heavy grazing. It also explains why using it as a hay crop sometimes results in loss of stand.
Allowing trefoil to stockpile generally weakens the plant. Lush growth that is allowed to stockpile is subject to stem diseases and insect infestations that may kill the plant. (BH: We can only wish!) Another danger in stockpiling material is creating a situation where rapid defoliation, such as clipping, would stress the plant, allowing root disease to completely kill the stand.
Fall management is especially important; avoid grazing between September and the middle of October. After this period, the growth may be used, but avoid extremely close grazing.
One fungal associate, Erysiphe betae and seven species of arthropods are reported to occur on Lotus including one bug and six lepidopterans.
http://plants.usda.gov/factsheet/pdf/fs_loco6.pdf
Wildlife: Birdsfoot trefoil is a choice food for Canada goose, deer, and elk. As ground cover, it provides green cover most of the year and blooms profusely. It is used for pheasant cover on shooting preserves and around ponds at duck clubs.
Hartman Conclusions: Birdsfoot trefoil was introduced as cattle forage. It produces an abundant amount of seeds which stay in the soil bank for years. We have been spraying it since 2001 with the goal of not letting it produce more seed and we believe that we have been mostly successful in doing this. Birdsfoot trefoil is still germinating, but we feel that the seed bank is being depleted. In a few years we expect to see no more new plants except from seed brought in on boots or vehicles.
The following is interesting info on BFT Cody found quickly on the web. All information to the end of this section is from the internet.
A couple things stuck out:
- Choice food for deer — explains how new plants are showing up far away from known populations. (BH: I strongly disagree! It is possibly moving on hooves but I vote for boots. I also do not believe that it is a food of choice for Nachusa deer who have better native plant options. In hundreds of hours of staring at birdsfoot trefoil, I have never seen any evidence of deer browsing it.)
- Planted heavily in poor soils to greatly improve forage yield in cattle — does not cause bloat.
- 375,000 seeds = 1 lb; 1 acre can produce 120 lbs of seed = 45,000,000 seeds per acre
http://extension.missouri.edu/publications/DisplayPub.aspx?P=G4640
Cody Considine says, “Pre–emergent herbicide will hopefully be the answer. I would still like to recruit a Master’s student to do their thesis on this plant.“
Trefoil and alfalfa initiate their first spring growth from stored energy in their root systems. After the growth is removed, alfalfa will replenish its root reserve in about 35 to 45 days throughout the growing season. Trefoil is noticeably different; it does not replenish its root reserves until fall and must depend upon photosynthesis from its leaves to supply energy for all of its regrowth during the late spring and summer. After about the first of September, trefoil once again will attempt to build up its root reserves that have been depleted since the first spring growth.
Trefoil's different way of storing root reserves explains why summer stockpiling of large amounts of growth usually results in stand depletion following the removal of this growth by heavy grazing. It also explains why using it as a hay crop sometimes results in loss of stand.
Allowing trefoil to stockpile generally weakens the plant. Lush growth that is allowed to stockpile is subject to stem diseases and insect infestations that may kill the plant. (BH: We can only wish!) Another danger in stockpiling material is creating a situation where rapid defoliation, such as clipping, would stress the plant, allowing root disease to completely kill the stand.
Fall management is especially important; avoid grazing between September and the middle of October. After this period, the growth may be used, but avoid extremely close grazing.
One fungal associate, Erysiphe betae and seven species of arthropods are reported to occur on Lotus including one bug and six lepidopterans.
http://plants.usda.gov/factsheet/pdf/fs_loco6.pdf
Wildlife: Birdsfoot trefoil is a choice food for Canada goose, deer, and elk. As ground cover, it provides green cover most of the year and blooms profusely. It is used for pheasant cover on shooting preserves and around ponds at duck clubs.
Hartman Conclusions: Birdsfoot trefoil was introduced as cattle forage. It produces an abundant amount of seeds which stay in the soil bank for years. We have been spraying it since 2001 with the goal of not letting it produce more seed and we believe that we have been mostly successful in doing this. Birdsfoot trefoil is still germinating, but we feel that the seed bank is being depleted. In a few years we expect to see no more new plants except from seed brought in on boots or vehicles.