Competition Control in Slash Pine Plantations

1
Competition Controlin Slash Pine Plantations
Silvics Analytic

• Dwight Lauer
• Silvics Analytic

2
Operational Competition Control
Silvics Analytic

• Pine response to vegetation control
• Knowledge of pine response is required to justify
  and select operational treatments
• What vegetation is competitive
• When vegetation is competitive
• Effect of duration of control
• Herbicide treatments and comparative responses
• Herbaceous weed control
• Woody shrub control

3
Competition and Pine Yield
Silvics Analytic
4
Competing vegetation
Silvics Analytic

• Woody shrubs
• gallberry (Ilex glabra)
• blueberries (Vaccinium spp.)
• Lyonias (Lyonia spp.)
• Herbaceous
• low panic grasses (Dicanthelium spp.)
• bluestems (Andropogon spp.)
• bracken fern (Pteridium aquilinum)
• Eupatorium spp.

5
Auburn University Silvicultural Herbicide
CooperativeSP-4F Study design
Silvics Analytic

• Objective was to determine the relative effects
  of woody shrubs and herbs on pine growth
• Woody shrub control
• None
• First year
• Repeated
• Herbaceous control
• None
• First year

6
Location of Studies
Silvics Analytic
7
Competition index(age 5 height loss)
Silvics Analytic

• CI 1.50 Ic 0.044 HC1 0.055 USC1 0.057 SC5
• CI competition index
• Ic 1 if from check treatment, 0 otherwise
• HC1 first year percent herbaceous cover ()
• USC1 untreated first year percent shrub cover
  ()
• SC5 fifth year percent shrub cover ()
• Ic could not be replaced by quantitative level
• R-square 0.84

8
Relationship between age 5 pine height and
competition index
Silvics Analytic
9
Age 5 basal area versus CIResponse ranges by
treatment
Silvics Analytic
10
Age 5 basal area versus CIRelated to age 15 MAI
(cords/ac/year)
Silvics Analytic
?2.2 2.8
?1.3
11
Competition and Pine YieldConclusions
Silvics Analytic

• Both woody shrubs and herbaceous vegetation
  decrease yield if present during the first
  growing season
• Extending the duration of control increases pine
  response
• Vegetation control treatments have the potential
  to double yield

12
Herbicide Treatments
Silvics Analytic

• First-year herbaceous weed control
• Selective treatments are available that can be
  applied over the top of planted seedlings
• Woody shrub control
• Pines are generally not tolerant to herbicides at
  the rates required
• Selectivity achieved by using pre-plant (site
  prep) applications

13
Herbaceous Weed Control Herbicides for Slash Pine
Silvics Analytic

• Arsenal (4-6 oz/ac)
• EscortOust
• EscortVelpar
• Oust (2-8 oz/ac)
• Oust Velpar (2 oz/ac 32 oz/ac is common)
• Oustar (12-16 oz/ac)

14
Response to HWC by soil type
Silvics Analytic

• Response information from herbaceous weed control
  and fertilization study (G-series)
• Response compared by CRIFF soil groups using year
  2 marginal response
• Height response per unit of cover controlled
• A-group soils without P fertilization did not
  respond to weed control
• No discernable pattern among soil groups

15
Response by soil groupYear 2 marginal response
based on G-series
Silvics Analytic
16
Woody Shrub Control Treatments for Slash Pine
Silvics Analytic

• Chopper (Arsenal)
• Garlon 4
• Chopper Accord
• Chopper Garlon 4
• Garlon 4 Accord
• Double bed

17
Pre-plant Herbicide vs. Double Bed
Silvics Analytic
18
SP4P 4 Treatments
Silvics Analytic

• Main plot treatments
• Early bed (5/98)
• Late bed (10/98)
• Double bed (EarlyLate)
• Banded pre-plant (10/98)
• Broadcast pre-plant (10/98)
• Pre-plant herbicide treatment
• 24 oz Chopper 2 qts Garlon 4 1 oz Escort

19
SP4P 4 Treatments
Silvics Analytic

• Half of each main-plot received banded herbaceous
  weed control
• 2 oz/ac Oust 32 oz/ac Velpar L (3/99)

20
SP-4P 4Year 2 Slash Pine Height
Silvics Analytic
21
Comparison of Operational Treatments
Silvics Analytic

• Pre-plant (site prep) treatments have improved
  the quality of vegetation control compared to bed
  spring HWC
• Control both shrubs and herbaceous vegetation
• Achieve responses similar to best treatments in
  the SP-4F research study
• Experimentation with timing of HWC treatments
  that extend the duration of herbaceous control
  would be of value

22
Operational TreatmentsNot all treatments are
created equal
Silvics Analytic

• Operational weed control systems must be
  developed through experience with registered
  herbicides in combination with other
  silvicultural practices