Clearcast Herbicide for Control of Tallowtree Todd Horton

1
Research and Technical Review of Clearcast for
Chinese Tallow Tree (Triadica sebifera)
Control Todd Horton SePRO Corporation Jack
Whetstone Clemson University
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Clearcast research and EUP results

• Clearcast was evaluated under an Experimental Use
  Permit (EUP) from 2005-2007
• Included multiple university trials
• Operational applications
• Demonstration plots
• Trials focused on submerged aquatic plants and
  wetland invasive and nuisance species
• Federal registration (section 3 label) approved
  in March 2008
• State registrations followed

3
Chinese tallow tree control

• Highly invasive woody plant found in coastal
  states from North Carolina to Texas
• Selective control in hardwoods is difficult
• Requires individual plant treatment

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Initial discovery

• 4-19-06, Houma, LA Clearcast at 0.5 was applied
  to mixed brush and hardwood species using a
  handgun delivering 50 gpa
• Broadcast rate equivalent to 32 oz/A (0.25 lb
  ai/A)
• Included 1 methylated seed oil (MSO)
• Although limited woody plant activity was
  anticipated, a single Chinese tallow tree was
  highly affected
• Other desirable woody plants, including water
  oak, were not injured

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Tallow tree and water oak at application 4-19-06
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Initial symptoms on tallow
June 26, 2006 (10 weeks after treatment)
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Other trials indicated hardwood selectivity

• Clearcast at 0.5
• MSO at 1
• 25 days after treatment
• Treated cattail and red maple

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Other trials indicated hardwood selectivity

• Clearcast at 0.5
• MSO at 1
• 63 days after treatment
• Cattail was controlled and red maple had minimal
  injury
• These findings led to further studies

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Tallow tree / Hardwood screening research and
demonstration

• LSU (Dearl Sanders) conducted a trial on sapling
  bald cypress (2006)
• Additional hardwood selectivity trial ongoing
  (2008)
• Numerous EUP applications in LA to further
  compile information on selectivity and control
• Lafayette, Hayes, Montgomery, Shreveport, Cade
• Aerial application trial with Clearcast in
  southeast Texas
• Cooperators include NRCS, BASF, ChemAir
• Aerial application trial with Clearcast in South
  Carolina
• Cooperators included TNC, SC DNR, Clemson
  University, BASF

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Cypress Screening (LSU Sanders)
64
32
24
16
8
4
0
Clearcast rate (oz/A)
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LSU StudySapling cypress leaf browning
() browning
(non-treated)
Clearcast (oz/A)
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LSU StudySapling cypress leaf browning

• Typical use rates necessary for Chinese tallow
  tree control (32-64 oz/A) did not result in bald
  cypress mortality
• Saplings would likely have the greatest
  susceptibility to herbicide injury
• Some leaf burning and browning was observed on
  saplings
• Symptoms peaked at 83 days after treatment, then
  subsided
• Additional field trials with Clearcast have
  documented bald cypress selectivity/safety
• Tested a wide range of size and age of cypress

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Tallow tree / Hardwood screeningLafayette, LA

• Clearcast at 0.5 1 MSO
• - Handgun app.
• 45 days after treatment
• Control of Chinese tallow tree in sensitive sites

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Tallow tree / Hardwood screeningLafayette, LA

• Clearcast at 64 oz/A 32 oz /A MSO
• - Handgun app.
• 6 Months after treatment
• Selective control of Chinese tallow tree in
  ditches and drainages

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Untreated
Clearcast 64 oz/A (note cambium death)
Arsenal Powerline (terrestrial herbicide)
Symptoms from Clearcast on Chinese tallow tree (6
Months after treatment)
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Tallow tree / Hardwood screeningHayes, LA

• Clearcast at 0.5 (equivalent to 32 oz/A) 1
  crop oil
• - handgun
• Selective control of Chinese tallow tree in a
  wetland site with cypress, oak, and maple
• 10 Months after treatment

Treated cypress tree (sprayed to wet)
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Tallow tree / Hardwood screeningHayes, LA

• Clearcast at 0.5 (equivalent to 32 oz/A) 1
  crop oil
• Selective control of Chinese tallow tree growing
  amongst cypress
• 10 Months after treatment

Treated both tallow and cypress trees
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Tallow tree / Hardwood screeningHayes, LA

• Clearcast at 0.5 (equivalent to 32 oz/A) 1
  crop oil
• Tallow tree controlled
• Adjacent oaks not damaged
• Note handgun reached only lower 1/3 to ½ of tree
• 10 Months after treatment

Treated tallow tree
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Tallow tree / Hardwood screeningHayes, LA

• Clearcast at 0.5 (equivalent to 32 oz/A) 1
  crop oil
• Tallow tree growing under and amongst cypress and
  maple
• Willows were controlled or severely injured
• 10 Months after treatment

maple
Cypress tree
Treated tallow tree
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Aerial (helicopter) trial in East Texas

• Wetland reserve program area near Liberty, TX
• 2, 5-acre sites applied 6-25-07 via helicopter at
  15 gpa
• Site 1 Clearcast at 48 oz/A MSO at 32 oz/A
• Contained a 9-year old planting of (10-20) bald
  cypress, nutall oak, willow oak, and water oak
• Moderate infestation of Chinese tallow tree
• Site 2 Clearcast at 64 oz/A MSO at 32 oz/A
• Uneven aged stand of mixed hardwoods with a
  moderate to severe infestation of tallow trees
  from 10 in the understory up to 50 in the
  canopy
• Canopy of 50-80 hardwoods (oak, maple, elm, ash)

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Aerial Clearcast results in Liberty, TX(site 1)

• Clearcast at 48 oz/A
• Excellent selectivity on oak and cypress
• Some leaf yellowing noticed on willow oak
• Leaf burn noticed during application year on
  cypress
• Full recovery 10 MAT
• Control of tallow estimated at 90 10 MAT with
  additional mortality anticipated

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Aerial Clearcast results in Liberty, TX (site 1,
48 oz/A)

• Clearcast at 48 oz/A
• Excellent selectivity on oak and cypress
• Controlled estimated at 90 10 months after
  treatment with additional mortality anticipated

tallow tree
willow and water oak
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Aerial Clearcast results in Liberty, TX (site 1,
48 oz/A)
tallow tree
nutall oak
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Aerial Clearcast results in Liberty, TX (site 1)

• Clearcast at 48 oz/A
• Other hardwoods with minimal impact included
  sweetgum, red maple, green ash, and wax myrtle
• Minimal impact on herbaceous species 10 MAT
• Injury noted on hawthorn and Baccharis

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Aerial Clearcast results in Liberty, TX (site 2)

• Clearcast at 64 oz/A
• Excellent hardwood safety
• 10 months after treatment Control of tallow
  estimated at 75-85 for plants that ranged from
  10-50 tall and received some coverage
• Limited coverage and shadowing affected control
  in the understory

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Aerial Clearcast results in Liberty, TX (site 2,
64 oz/A)
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Aerial Clearcast results in Liberty, TX (site 2,
64 oz/A)
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48 oz Imazapyr
64 oz Imazapyr
96 oz Glyphosate
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Aerial (helicopter) trial in South Carolina

• June 2006, helicopter application at 10 gpa
• Treated with Clearcast at 64 oz/A 1 MSO
• Site had a mixed stand of hardwoods and Chinese
  tallow tree
• Also targeted phragmites

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Selective Tallow and Phragmites(1 year after
treatment)
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Clearcast Chinese Tallow

• 32 Oz. Clearcast 1 MSO in 15 Gallons
• 10 August 2006
• 11 DAT

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Summary of research on brush and tallow tree
control

• 32-64 oz/A Clearcast has controlled Chinese
  tallow tree in numerous trials and demonstration
  plots
• Higher rates are necessary for severe
  infestations and mature stands
• Lower rates may suffice for small tallow trees
  and will provide greater safety for small
  hardwoods
• Similar results have been observed with
  ground/handgun applications and aerial helicopter
  applications
• Application method and volume should provide
  adequate foliar coverage of crown and terminal
  shoots
• 10-15 GPA aerial
• 50 GPA handgun
• 20-50 GPA broadcast ground
• MSO at 1 or 32 oz/A used in all trials to date

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Summary of research on brush and tallow tree
control

• Majority of established hardwoods (gt2 dbh) in
  these trials have exhibited very good tolerance
  to Clearcast at 32-64 oz/A
• Oak (live, nutall, water, willow) Sugarberry
• Bald cypress Southern Red Cedar
• Red maple Groundsel-tree (Baccharis)
• Hickory Elm
• Red Mulberry Hackberry
• Wax Myrtle Green ash
• Pecan
• Loblolly Pine
• Injury is possible on stressed plants and smaller
  trees
• Willow, black cherry, hawthorn, sweetgum and
  sumac are among the sensitive/susceptible woody
  species
• Sweetgum may be controlled at higher volumes,
  smaller trees

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Additional Information

• Clearcast has a full aquatic label with no
  fishing, swimming, or livestock watering
  restrictions
• Label also allows for applications in noncropland
  and riparian areas
• The active ingredient in Clearcast received an
  exemption from tolerance designation from the US
  EPA
• Thus, Clearcast has limited irrigation
  restrictions (50 ppb) and
• University trials have illustrated safety to
  turf, corn, cotton and rice at rates below 50 ppb

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Additional Information

• Clearcast also has activity on a wide range of
  nuisance and invasive aquatic weeds including
• Alligatorweed Common salvinia
• Pennywort Frogsbit
• Phragmites Cattail
• Water lettuce Water hyacinth
• Pondweeds

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Acknowledgements

• Dearl Sanders, LSU
• Barton Joffrion, Terra Bonne Extension
• Mitch Samaha, LDWF
• Tom Smith, USDA-NRCS
• Jack Whetstone, Clemson
• Red River, Chemair
• C3M, Summit Helicopters

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SePRO Contact Information For tallow control and
other pond management problems Todd
Horton 864-270-5292 toddh_at_sepro.com