Wildfires and Invasive Plants

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Wildfires and Invasive Plants

• Carl E. Bell
• Regional Advisor Invasive Plants
• University of California Cooperative Extension
• San Diego, CA

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Fire Photo Project

• Started in December 2003
• 32 continuing quarterly photo points through 2008
• Recovery slow in most cases, especially at lower
  elevations (CSS)
• Winter 04, 06, 07 very dry
• Winter 05 wet
• Winter 08 winter rains were timely, but not heavy
• Some points burned again in 2007
• Many carried by invasive annual grasses

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Is there anything we can do to break this
fire-weed cycle?
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Active Management of invasive plants.

• Control of invasive annual grasses and forbs
• Techniques could include
• Controlled burns
• Mowing
• Grazing
• Herbicides
• Combinations of any or all above (IVM)

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Active Management Techniques
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Herbicides as active management tools in Southern
CA
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Barnett Ranch Sites B C

• Data collected
• Plant and soil cover in fixed quadrats once per
  year
• Time required to spray herbicide
• Amount of herbicide used per treatment

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Barnett Ranch Sites B C

• Herbicide treatment responses 2007 (after
  replanting)
• Site B
• Exotic forbs cover 5 vs 32 for UTC
• Exotic grass cover 1 vs 13 for UTC
• Native forb (17 species) cover 18 vs 2 for UTC
• Site C
• Exotic forb cover 11 vs 4 for UTC
• Exotic grass cover 21 vs 90 for UTC
• Native forb cover 26 vs 2 for UTC

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Barnett Ranch Sites B C Herbicide
application data

• Broadcast application to emerged weeds before
  emergence of native annuals
• 3/26/06 2/15/07 1/22/08
• 2 qts/A Roundup-Pro 15 minutes/A to spray (4
  acre/hr)
• Spot spray application to weeds that emerged
  after the broadcast spray
• 5/25/2006 5/2/2007 4/10/2008
• 3 to 9 hr/A
• ca 0.6 qt of Roundup/A

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Nassella pulchra tolerance to herbicides San
Diego and Los Angeles Counties

• To evaluate purple needlegrass tolerance to
  postemergence herbicides
• Cooperators and Co-PIs
• Marti Witter, Jennifer Carlson, Joseph Algiers,
  NPS, Santa Monica Mountains NRA John Ekhoff, CA
  DFG
• Three sites
• Cheeseboro Canyon, SMMNRA (weed-free)
• Rancho Jamul Ecological Reserve, CA-DFG (two
  sites 2007 and 2008)

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Nassella pulchra tolerance to herbicides San
Diego and Los Angeles Counties

• Herbicides applied in spring to established
  purple needlegrass
• Herbicide treatments include
• Fluazifop-butyl (Fusilade)
• Clethodim (Envoy)
• Glyphosate (Roundup)
• Pelargonic acid (Scythe)
• Imazapic (Plateau)
• Trifluralin (Preen granules)
• Aminopyralid (Milestone)
• Triclopyr (Garlon)

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Nassella pulchra tolerance to herbicides San
Diego and Los Angeles Counties

• SMM site
• Herbicide applied 1/22/07
• Plots sampled on 5/23/07 for biomass, basal
  diameter, inflorescences per plant, and visual
  injury
• No significant difference (p0.19) between
  treatments and the UTC for biomass
• No apparent injury related to treatment

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Nassella pulchra tolerance to herbicides San
Diego and Los Angeles Counties

• RJER site, 2007 trial
• Herbicides applied postemergence 2/9/07
• N. pulchra injury
• 6 WAT - 20-80 depending upon herbicide
• 6 MAT 10-60
• N. pulchra mean weight per plant 6 MAT
• Fluazifop 47.3 g
• Clethodim 26.8 g
• Glyphosate 63.3 g
• Aminopyralid 53.9 g
• UTC - 15.0 g

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Nassella pulchra tolerance to herbicides San
Diego and Los Angeles Counties

• RJER site, 2008 trials
• Both sites burned in 2003 and 2007
• Site One reapplication 12/28/07 to 2007
  experiment
• Site two new experiment same treatments
  applied on 1/18, 2008
• N. pulchra injury
• Fluazifop 10-20
• Clethodim 20-60
• Glyphosate 0-30
• Aminopyralid 0-5
• UTC - 0

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Why Active Management?