Non Native Invasive Plants Workshop Albemarle, NC October 12, 2012 Bill Pickens Conifer Silviculturalist North Carolina Forest Service

Transcription

1 Herbicides in Forestry Factors That Influence How Herbicides Work Non Native Invasive Plants Workshop Albemarle, NC October 12, 2012 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 You mean herbicides aren t all the same

3 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

4 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

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

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12 What are Adjuvants??? Answer: anything added to a pesticide spray mix to increase effectiveness Improve delivery or penetration and retention on foliage.

13 Increase Effectiveness Adjuvants Surfactants chemicals that modify the surface properties of materials they contact and influence the wetting or spreading of the liquids. 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 Penetrantsa surface enhance a liquid s ability to enter pores or penetrate

14 Improve Delivery Adjuvants Emulsifiers enable oils to be mixed in water. Defoamers reduce surface tension of bubbles. Buffers reduce ph of alkaline waters.. Drift Control Agents reduce spray drift

15 Surfactants and Oils Increase spread on leaf improving absorption Increase deposition efficiency on leaf surface

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

17 How Do Herbicides Work? Disrupt one or more vital processes Highly specific Enzyme Building Block

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

19 Behavior in Plants Consider: Site of Absorption Translocation Site of Physiological Action Symptoms

20 Herbicides are Grouped into Families with Common Modes of Action Growth Regulators ex. Garlon, Transline, Milestone Photosynthetic Inhibitors ex. Velpar Amino Acid Inhibitors ex. Arsenal, Accord, OUST, Escort Mitosis inhibitors ex. Krenite

21 Growth Regulators Family Common Name Trade Name Phenoxyacetic Acid Pyridine- Carboxylic Acids (Picolinic Acid) 2,4-D, 2,4-DP Triclopyr Clopyralid Aminopyralid Weedone many others Garlon Transline Milestone

22 Growth Regulators: Absorption 2,4 D, 2,4 DP: plant roots absorb the polar amine forms ester forms penetrate the foliage rapidly. Triclopyr: ( Garlon) Primarily absorbed by foliage; root uptake does occur, primarily for the water soluble amine Clopyralid: (Transline) Readily absorbed by roots and foliage

23 Growth Regulators: Translocation All translocate via the xylem and phloem but most movement is in the phloem and within the cells. Following root absorption translocation is primarily in the xylem All accumulate in growing points Differences in translocation between species account for differential susceptibility.

24 Growth Regulators: MOA Not completely understood, similar to exogenous auxin (IAA). Many processes affected. Primarily effects cell wall plasticity and nucleic acid metabolism. Cell wall is acidified through stimulation of the ATPase driven proton pump, increasing cell wall elongation through action of loosening enzymes. Low concentrations stimulate RNA polymerase, resulting in increases in RNA and DNA, stimulating protein synthesis.

25 Growth Regulators: Symptoms Bending and twisting of stems and petioles, stem swelling at nodes, stem elongation, and leaf cupping and curling Chlorosis of growing points, growth inhibition, wilting, and necrosis. Death of susceptible plants occurs within 3 5 weeks. In woody plants rapid necrosis of foliage may reduce effectiveness of translocating herbicides.

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27 Photosynthesis Inhibitors Family Common Name Trade Name Triazine Hexazinone Velpar Atrazine Aatrex Others

28 Hexazinone Absorption and Translocation Absorbed through roots with soil applications and translocated upward through xylem Absorbed through leaves following foliar applications but poorly translocated to other plant parts atrazine, essentially no (downward) movement from leaves.

29 Hexazinone MOA and Symptoms Photosynthesis inhibitor: Inhibits electron transport in photosystem II Symptoms begin with interveinal chlorosis and yellowing of leaf margins and progress to necrosis. Older leaves show more symptoms than new growth

30 Inhibitors of Amino Acid Synthesis Family Common Name Trade Name Organophosphorus Imidazolinone Sulfonylureas Glyphosate Imazapyr Imazapic Sulfometuron methyl Metsulfuron methyl Accord Roundup Many Others Arsenal Plateau Oust Escort

31 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.

32 Glyphosate: Mode of Action Inhibits the formation of aromatic amino acids (tryptophan, tyrosine, and phenylalanine). The site of action is the enzyme EPSP (enolpyruvyl shikimate 3 phosphate). Having a very specific site of action facilitates development of herbicide resistance.

33 Glyphosate: Symptoms Symptoms appear relatively slowly (4 7 days). Growth is inhibited soon after application foliar chlorosis and necrosis, appearing first in in new growth. Foliage sometimes turns reddish purple in certain species.

34 Imazapyr Absorption and Translocation Absorbed through roots and foliage Rapid translocation throughout the plant through the xylem and phloem. Accumulates in symplasm through iontrapping mechanism.

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

36 Imazaypyr Symptoms Growth is inhibited after a few hours Symptoms are very slow to develop; 1 3 weeks in herbaceous plants to several months in woody plants. Symptoms first occur in growing points as yellowing then progressing to necrosis. Certain plants develop a black color in foliage, purple colored sap in trees.

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38 Oust & Escort Absorption and Translocation Readily absorbed by leaves following post treatments and by roots from treated soil. Move primarily in the xylem and to a limited extent by mass flow in the phloem. Accumulate in meristematic regions of the plant.

39 Oust & Escort Symptoms Growth is inhibited after a few hours but symptoms are very slow to develop; 2 3 weeks in herbaceous plants to several months in woody plants. Symptoms gradually appear as chlorosis in growing points then progress to chlorosis and necrosis of the foliage.

40 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. Moorhead David J., P. Minogue, E.D. Dickens Herbaceous weed control recommendations for planted loblolly pine sites.

41 Read and follow the label!! Questions?

42 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