Herbicides in Forestry Factors That Influence How Herbicides Work. Bill Pickens Conifer Silviculturalist North Carolina Forest Service

Transcription

1 Herbicides in Forestry Factors That Influence How Herbicides Work Bill Pickens Conifer Silviculturalist North Carolina Forest Service

2 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

3 Terminology for Herbicide Characteristics Activity Foliar or Soil Herbicides with both are often most effective Soil active can be persistent Pre Emergent or Post emergent Selectivity What plant(s) does the herbicide target? Is your crop tree on the list?

4 Terminology for Herbicide Characteristics Persistence How will desirables be impacted? What s a half life? What degrades it? Salts or Ester Salts are water soluble Salts require a surfactant Ester are volatile Ester penetrate woody tissue more readily

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

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

7 Right Herbicide +Timing + Rate = Success

8 Right Herbicide +Timing + Rate Forest Productivity Cooperative

9 Right Herbicide +Timing + Rate

10 Right Herbicide +Timing + Rate

11 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

12 The Herbicide Mix Active Ingredient (formulated as a Salt or an Ester) plus. a Carrier usually water plus an Adjuvant(s)

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

14 Surfactants (Wetter, Spreader, Sticker) Oils Emulsifiers Water Conditioners Drift Mitigation Foam Reducers Colorants 4000 products in US Largely not regulated

15 Surfactants and Oils Increase spread on leaf improving absorption Increase deposition efficiency on leaf surface Poor coverage Droplet bounce

16 WATER OIL

17 Wetting agents reduce surface tension increasing droplet spread and uptake Herbicide in water Herbicide in water plus surfactant

18 Common products Surfactants Non ionic surfactant such as polyethoxylates, 1 3 quarts per 100 gal spray ( % solution) Silicone, containing silicone Oils Crop oils, paraffin derived from mineral oil Basal oils, mixed mineral oils containing paraffin, aromatic and napthelene Methylated seed oil (MSO), esterified free fatty acids from plant glycerol (biodeisel) Tallow amine, free fatty acids from animal fat

19 How Do Herbicides Work? Various modes of action Growth Regulators Amino Acid Inhibitors Photosynthesis Inhibitors Mitosis inhibitors Cell membrane destroyers Lipid Biosynthesis Inhibitors You mean herbicides aren t all the same

20 Behavior in Plants Consider: Site of Absorption Into Plant Translocation Within the Plant Site of Physiological Action Symptoms, Fast vs. Slow

21 Herbicide Modes of Action Growth Regulators or Auxin mimics Garlon, Tordon, 2,4 D Auxin overdose Many processes affected. Not completely understood. The specific site of action has not been identified. Primarily effects cell wall plasticity and nucleic acid metabolism. Cell wall is acidified and elongation

22 Herbicide Modes of Action Growth Regulators or Auxin mimics Foliar Active (some soil ) : most movement is in the phloem and cell to cell the symplasm membranes Epinastic bending and twisting, stem swelling and elongation, and leaf cupping and curl All accumulate in growing points

23 Cut stump treatment targeting hardwoods

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

25 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

26 Amino Acid inhibitors Accord, Arsenal/Chopper, Oust, Escort Enzyme Building Block

27 \ Enzyme Herbicide Building Block

28 Glyphosate: Absorption and Translocation Absorption is through the foliage. strongly binded by soil root uptake occurs only to a very limited extent in sandy soils with high rates and saturated conditions. Primarily translocated in the phloem and within the symplasm little to no movement in the xylem. Glyphosate accumulates in underground tissues, immature leaves, and meristems.

29 Glyphosate: Mode of Action Inhibits the formation of aromatic amino acids (tryptophan, tyrosine, and phenylalanine). Having a very specific site of action facilitates development of herbicide resistance.

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

31 Accord, Roundup Glyphosate Non selective herbicide Symptoms first evident on new growth Pigment loss Growth stoppage Distorted growth Fast symptoms, slow death

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

33 Imazapyr Absorption and Translocation Soil and Foliar Active absorbed through roots and foliage Rapid translocation throughout the plant through the xylem and phloem. Accumulates in symplasm through iontrapping mechanism.

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

35 Arsenal AC, Chopper Imazapyr Non selective (but tolerated by some conifers) and Controls a broad range of grasses, broadleaved herbs, and woody species Post Emergent Persistent Average soil half life is days

36 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

37 Herbicide Modes of Action Photosynthesis Inhibitors Hexazinone (Velpar) ; Paraguat Photosynthesis inhibitor: Inhibits electron transport in photosystem II Soil Active : Absorbed through roots with soil applications and translocated upward through xylem Needs soil moisture to activate; leaches readily

38 Herbicides in Forestry Herbicide Modes of Action Mitosis inhibitors (mersitems) Krenite Cell membrane destroyers Paraquat Lipid biosynthesis inhibitors Poast, Vantage, Fusilade

39 Source of Information Herbicide Handbook S.A. Senseman, Ed.. Nineth Edition, Weed Science Society of America, 810 E. 10 th Street, Lawrence, KS (ISBN ) Osiecka, A. and P. Minogue Forest herbicide characteristics. University of Florida Cooperative Extension Service Circular FOR pp. Osiecka, A. and P. Minogue Developing herbicide prescriptions for forest vegetation management. University of Florida Cooperative Extension Service Circular FOR pp.

40 Read and follow the label!! Questions?