Ecologically Based Management of Salt Cedar

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Ecologically Based Managementof Salt Cedar

• K. George Beck
• Bioag Science Pest Management
• Colorado State University

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References

• Sheley, R.L., T.J. Svejcar, B.D. Maxwell.
  1996. A theoretical framework for developing
  successional weed management strategies on
  rangeland. Weed Technology 10766-773
• Sheley, R.L., S. Kedzie-Webb, B.D. Maxwell.
  Integrated weed management on rangeland. in R.L.
  Sheley J.K. Petroff, eds. Biology Management
  of Noxious Rangeland Weeds p 57-68

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Ecologically Based Weed Management

• Develop strategies based upon current
  understanding of succession
• Recognizes plant communities dynamic
• Use technology to enhance natural processes
  mechanisms that regulate vegetation change
• Direct weed infested communities on trajectory to
  more desirable community

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Causes of Succession

• Site availability
• Differential species availability
• Differential species performance
• Successional weed management exploits these causes

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Successional Weed Management Components

• Mgmt component
• Designed disturbance
• Controlled colonization
• Controlled species performance

• Succession cause
• Site availability
• Differential species availability
• Differential species performance

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Ecological Opportunities forWeed Management
Designed disturbance
Undesired plant community
Desired plant community
Time
Controlled colonization
Controlled performance
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Successional Weed MgmtTreatment Examples
Designed Disturbance
Controlled Colonization
Controlled spp Performance
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Biological Control of Salt Cedar

• Several speakers to address this issue
• biocontrol can be controlled colonization and
  controlled species performance components of
  successional weed mgmt

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Reference

• Brock, J.H. 1994. Tamarix spp. (Salt Cedar), an
  invasive exotic woody plant in arid and semi-arid
  riparian habitats in western USA. p.27-44 In
  L.C. de Waal, L.E. Child, P.M. Wade, and J.H.
  Brock, eds. Ecology and management of invasive
  riverside plants. John Wiley sons, West
  Sussex, England.

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Physical or Mechanical Control

• Fire
• not effective for controlling salt cedar
• readily resprouts from crown at rate of 3 to 4 M
  per year
• 20 A fire in UT summer 1975
• 1 year later fire effects observable
• but with surface of lush green salt cedar
  regrowth over entire area
• 1978 salt cedar fully recovered

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Physical or Mechanical Control

• Fire
• UT research repeat burning
• during spring, summer, fall for 2 years
• no effective control because of regrowth from
  crowns

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Physical or Mechanical Control

• Shredding, rollerchopping, chaining
• all designed to decrease canopy of target species
  and ideally decrease plant density
• fails to do so on salt cedar

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Physical or Mechanical Control

• Grubbing
• cutting individual plants to a depth of more than
  20 cm deep also does not work well on salt cedar
• regrowth evident following this technique within
  6 to 12 months

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Physical or Mechanical Control

• Root plowing
• using horizontal blade more than 20 cm deep
  controlled 40 of salt cedar in NM
• must repeat operations to achieve greater control
• In AZ, 1 M long ripper blades set 1 M apart
  pulled with D9 crawler kept portion of Salt River
  nearly free of SC for 10 yr
• must repeat at about 10 month intervals

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Physical or Mechanical Control

• Flooding (Inundation)
• inundation of established SC 24 to 36 months
  caused 99 control
• flooding during growing season
• inundation also prevents seedling establishment
• established SC withstood
• root crowns flooded for 98 days
• total submersion for 70 days

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Reference

• Duncan, K.W. and K.C. McDaniel. 1998. Saltcedar
  (Tamarix spp.) management with imazapyr. Weed
  Technology 12337-344.

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Chemical Control

• First chemicals used
• 2,4-D, 2,4,5-T, silvex
• controlled topgrowth
• regrowth always occurred
• 2,4,5-T silvex banned 1983

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Chemical Control

• Triclopyr (Garlon 3A)
• used to treat individual plants
• fairly effective
• 1.5 solution v/v in 300 gallons total spray
  solution per acre!!
• Thorough coverage necessary
• May best timing, August also good

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Chemical Control

• Imazapyr (Arsenal)
• Treating individual plants
• 1 v/v solution in water sprayed to wet,but not
  to drip
• generally 90 control
• best control in August or September (99)
• control less when sprayed in April or October
• an expensive treatment

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Salt Cedar Mortality1 Solution Arsenal
May
Jun
Jul
Aug
Sep
Oct
Individual plants treated
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Chemical Control

• Imazapyr (Arsenal) glyphosate (Roundup or
  Rodeo) individual plants
• often imazapyr glyphosate tank-mixed
• decrease treatment expense
• 0.5 0.5 v/v solution 0.25 NIS
• controlled 95 of SC regardless of date of
  application during growing season
• glyphosate at 2 v/v
• only 32 control

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Chemical Control

• NMSU guidelines treating individual plants
• young or regrowth SC
• easier to trt better control
• trt areas root plowed, mowed, or cleared or where
  SC starting to invade
• trt areas
• glyphosateimazapyr 0.5 0.5 v/v 0.25 nis
• comparable to 1 v/v imazapyr
• spray foliage to wet, especially terminal ends of
  branches
• allow 2 full seasons before follow-up trts

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Chemical Control

• Broadcast - carpet roller
• imazapyr glyphosate 0.125 0.125 or imazapyr
  at 0.125
• controlled 85 92 of SC 2 YAT
• mortality dropped to 32 when solution decreased
  to 0.1 0.1
• glyphosate alone 0.5, 5 mortality
• imazapyr alone 0.25, 94 mortality

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Chemical Control

• Broadcast - carpet roller
• good because only contacts target vegetation
• understory protected
• many plants went untreated
• decreased with increased operator experience
• treat only plants

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Chemical Control

• Aerial applications
• NMSU evaluated fixed wing
• 1993 1994 data 2 YAT
• compared imazapyr at 0.75 lb ai/A to mixtures of
  imazapyr and glyphosate
• control ranged from 66 (imazapyr 0.75 lb) to 87
  (0.5 0.5 lb imazapyr glyphosate)

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Fixed Wing Treatments Imazapyr Glyphosate
Ima 0.75
IG 0.250.5
IG 0.380.38
IG 0.380.5
IG 0.50.5
Data taken 2 YAT
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Chemical Control

• Aerial applications
• aircraft fit with conventional raindrop nozzles
• delivered 7 gpa
• when changed to microaire nozzles at 3 gpa
• control decreased 10 to 15
• Upshot - higher gallonage important for coverage
  to penetrate canopy

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Chemical Control

• Aerial applications
• also found helicopter applications caused highly
  variable control
• 31-90 with no apparent rate response
• generally taller trees harder to control
• trees with higher number of stems harder to
  control

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Tree Ht Stem Number Influences Control
Stem numbers 1-4 5-9 10-19 20
Tree ht
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Reference

• Taylor, J.P. and K.C. McDaniel. 1998.
  Restoration of Saltcedar (Tamarix spp.)-infested
  floodplains on the Bosque del Apache National
  Wildlife Refuge. Weed Technology 12345-352.

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Ecologically Based SC Mgmt

• Designed disturbance
• root plowing
• pile burn
• Controlled colonization
• spot trt SC regrowth imazapyr or imazapyr
  glyphosate individual trees
• experience shows plowing, burning, spray better
  than spray, chain or burn, spray
• cost about 1/3 as much
• planted many native spp

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Ecologically Based SC Mgmt

• Controlled species performance
• drip irrigation
• ultimately mimic natural flooding by controlled
  water manipulations
• while stimulates SC recruitment, experience shows
  that remains minor component of overall flora

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Summary

• These are just examples
• many treatment combinations that work
• Always
• know starting composition plant community
• know what composition trying to achieve
• thru designed disturbance, controlled
  colonization, controlled species performance
• put succession on trajectory to achieve desirable
  plant community