How Herbicides Work. Herbicides in Forestry. Non-Native Invasive Plants Workshop Wilkesboro, NC May 8, 2012

Transcription

1 Herbicides in Forestry How Herbicides Work Non-Native Invasive Plants Workshop Wilkesboro, NC May 8, 2012 Bill Pickens Conifer Silviculturalist North Carolina Forest Service

2 Outline Herbicide Terminology - classifies by characteristics Factors that affect herbicide efficacy Herbicide Mode of Action Review specific characteristics of some common forestry herbicides

3 Plant physiology, bio-chemistry, agronomy, research, environmental conditions, plant identification, safety, certification, licensing There s a lot to know And they are not created equal

4 Terminology for Herbicide Characteristics Foliar vs Soil Active Herbicides with both are often most effective Soil active can be persistent Pre- Emergent vs Post emergent Selective vs non selective Selective can target specific NNI

5 Terminology for Herbicide Characteristics Persistent vs non- persistent What s a half life? What degrades it? How will desirables be impacted? Salts vs Ester Salts are water soluble Salts require a surfactant Ester are volatile Ester penetrate woody tissue more readily

6 Active Ingredient Trade Name Preemergent Postemergent Selective Nonselective Limited mobility Xylem Translocated Phloem Translocated Persistent Non- Persistent Glyphosate Accord x x x x Triclopyr Garlon x x x x 2,4-D x x x x Hexazinone Velpar x x x x x x Imazapyr Arsenal x x x x x x Metsulfuron Escort x x x x x x Clopyralid Transline x x x x x Sulfometuron Oust x x x x x x x Picloram Tordon x x x x x x Fosamine Krenite x x x x

7 Factors that affect Herbicide Effectiveness Stage of growth of plants Leaf shape and texture Soil texture, ph Plant species (resistant vs. susceptible)

8 Factors that affect Herbicide Effectiveness Temperature Drought Soil Moisture Rainfall after application Light Tank mixes and antagonism Water quality

9 Right Herbicide +Timing + Rate = Success

10 Right Herbicide +Timing + Rate Forest Productivity Cooperative

11 Right Herbicide +Timing + Rate

12 Right Herbicide +Timing + Rate

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14 What are Adjuvants??? Answer: anything added to a pesticide spray mix to increase effectiveness Improve --delivery, retention on foliage, penetration,

15 Types of Adjuvants Surfactants- ---chemicals that modify the surface properties of materials they contact and influence the wetting or spreading of the liquids. Defoamers --- reduce surface tension of bubbles. Buffers --- reduce ph of alkaline waters. Crop oils --- petroleum or vegetable oil based product usually 2% emulsifier and 98% oil added for dissolving waxy surfaces. Crop oil concentrates---petroleum or vegetable oil based usually 15-20% emulsifier and 80-85% oil. Drift Control Agents- reduce spray drift Penetrants- enhance a liquid s ability to enter pores or penetrate a surface Emulsifiers- enable oils to be mixed in water.

16 How Do Herbicides Work? You mean herbicides aren t all the same

17 Herbicides in Forestry Plants Complex organisms: physiological processes Growth Development Photosynthesis Respiration Defense Reproduction Transpiration Protein Synthesis Fatty Acid Metabolism 1000 s more.

18 Herbicides in Forestry Herbicide Modes of Action Disrupt one or more vital processes Highly specific Enzyme Building Block

19 Herbicides in Forestry Herbicide Modes of Action Disrupt one or more vital processes Highly specific Enzyme Herbicide Building Block

20 Herbicides in Forestry Herbicide Modes of Action Auxin mimics Garlon, Tordon, 2,4-D Amino acid inhibitors Accord, Arsenal Photosynthesis inhibitors Velpar, Paraguat Mitosis inhibitors (mersitems) Krenite Cell membrane destroyers Paraquat Lipid biosynthesis inhibitors Poast, Vantage, Fusilade

21 Imazapyr Arsenal AC, Chopper Foliar Applications Site Prep Pine release (fall) Cut Stump Tree Injection

22 Imazapyr Arsenal AC, Chopper Amino acid inhibitor (branched chain) Isoleucine, Leucine, and Valine are not produced

23 Arsenal AC, Chopper Imazapyr Non-selective --(but tolerated by some conifers) Post Emergent Control -- broad range of grasses, broadleaved herbs, and woody species Symptoms appear slowly -- in youngest leaves first (chlorosis) Persistent -- Average soil half life is days

24 Arsenal AC, Chopper Imazapyr Below ph of 5, dry conditions, low temps Binds to clay and organic matter Very persistent in soil Stable in soil for more than a year at normal temperatures Above ph of 5 It may leach from soil more available to the plant Degradation is slowed

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26 Glyphosate Accord, Roundup, One Step Site prep and Release Foliar application Cut stump Tree Injection

27 Glyphosate Accord, Roundup, One Step Site prep and Release Foliar application Cut stump Tree Injection

28 Glyphosate Accord, Roundup, One Step Amino acid inhibitor (aromatic)

29 Glyphosate Accord, Roundup, One Step Non-selective herbicide Foliar applications only Symptoms first evident on new growth Pigment loss Growth stoppage Distorted growth Fast symptoms, slow death

30 Glyphosate Accord, Roundup, One Step Deactivated by soil, dust Post emergent Non-Persistent does not leach Absorbed by green tissues only Can volatilize on hot days!

31 Oust Foliar Spray Site prep Pine release Pre-emergent Persistent Sulfometuron Methyl Most effective against grasses and broadleaf weeds in early stages of growth

32 Oust Non-selective Sulfometuron Methyl Accumulates in mersitems Symptoms first show 2-3 weeks after application Death (4-6 weeks)

33 Oust, Oustar Persistent at soil ph > 6.8 Cold dry conditions after application slow activity Sulfometuron Methyl Leaches out of soils, especially at higher phs Usually short-lived in the soil, but persistence has been observed under some conditions (2+ years)

34 Garlon, Pathfinder Auxin Growth Regulator Site prep & TSI Foliar application Tree Injection Cut stump Basal bark Should not contact pine foliage, directed applications only, may cause temporary injury Triclopyr

35 Garlon, Pathfinder Triclopyr Selective --effective against broad leaf species only, not grasses Rapidly taken up by roots and leaves and transported to growing tissues

36 Garlon, Pathfinder Triclopyr Volatile, high danger of drift In the soil, it is rapidly deactivated, but does not bind to soil particles Usually degrades in 30 days

37 Pathway, Tordon Auxin Growth Regulator Site prep and TSI Foliar application Cut stump Basal Bark Picloram Effective against broad leaf species only, not grasses Taken up readily by roots, less so by foliage

38 Pathway, Tordon Picloram May leach from roots of treated plants Readily leaches out of soil, but may bind to organic matter Usually persists in soil for less than 3 months, but organic matter and/or dry conditions drastically increases halflife (3+ years) Toxic to pines, especially when stressed

39 Cut-stump treatment targeting hardwoods

40 Read and follow the label!! Questions?