Chemical Control of Aquatic Weeds. Ryan M. Wersal, PhD Lonza Microbial Control, Alpharetta Innovation and Technology Center

Transcription

1 Chemical Control of Aquatic Weeds Ryan M. Wersal, PhD Lonza Microbial Control, Alpharetta Innovation and Technology Center

2 Benefits of Aquatic Plants Stabilize lake sediments, reduce resuspension Increase sedimentation, reduce turbidity Provide habitat for insects, forage fish, fish spawning and YOY fish Provide food for waterfowl, other animals

3 Native Vs. Non-native

4 Plant Species Designation Aquatic plant species can be designated as: Native Non-native Invasive Native Invasive Non-native Invasive And Others (i.e. Non-native Naturalized) This often creates confusion with the public and resource managers As well as determining management strategies Including herbicide selection

5 Goal of Management Remove nonindigenous plants and restore a diverse community of desirable native plant species Pretreatment 4 WAT 12 WAT Pond near Starkville, MS 70% coverage by waterhyacinth

6 What Do Herbicides Do? Controlled/selective plant poisoning applied to soil (root uptake), water, and/or leaves (foliar uptake) contact or systemic selective vs. non-selective

7 How Herbicides Work Mode/mechanism of action, where a specific plant process is targeted photosynthesis pigments enzymes growth hormonal balance DQ DQH 2 O 2 -

8 Advantages of Herbicide Use Cost effective Predictable, consistent efficacy Relative ease of application Minimal ecosystems impacts

9 Advantages of Herbicide Use Can treat small as well as large areas Proper choice, rate, timing = selectivity Newer Products excellent toxicology profiles Compatible with other management options Best tool for initially removing large amounts of nuisiance vegetation

10 Disadvantages of Herbicide Use Commitment to long-term management Use restrictions When/where you can apply Drinking, swimming, fishing, irrigation, livestock Can sometimes select for a worse problem Target plants can recover Public perception of chemical use Human/eco-toxicology issues Fear of pesticides

11 Misconceptions with Aquatic Herbicides Aquatic plants take up most of the herbicide Plant uptake = 1 to 5% of herbicide Herbicides mix rapidly top to bottom Herbicide trapped via thermal gradients Dispersion is a minor factor All 3 ppm treatments should work the same Wind/Flow move herbicide off-target Herbicides Are Dumped Into the Water

12 Potential Environmental Concerns Potable Water Lowered dissolved oxygen (DO) and warm water Whole vs. Partial treatment Fish mortality may result Nutrients released Increased turbidity (algal bloom) Crop/landscape damage due to irrigation (MS Delta alligatorweed and soybeans) Choice of herbicide 1/2 life, sensitivity of non-target plants Posting requirements Time, Setback Distance, Herbicide Concentration

13 13 Herbicides Registered for Section 3 herbicides Aquatic Use All products have terrestrial uses Glyphosate and 2,4-D - major use on food crops Glyphosate and Imazapyr - Emergent Copper, Endothall, Fluridone - Submersed Diquat, 2,4-D, Triclopyr, Carfentrazone, Imazamox, Penoxsulam, Flumioxazin, and Bispyribac-sodium Emergent and submersed uses

14 Aquatic Herbicide Mode of Action 2,4-D Bispyribac-sodium Carfentrazone-ethyl Copper Diquat Endothall Flumioxazin Fluridone Glyphosate Imazamox Imazapyr Penoxsulam Triclopyr Auxin mimic / plant growth regulation Plant enzyme inhibition / ALS Inhibits PPO enzyme / chlorophyll Inhibits photosynthesis Inhibits photosynthesis Respiration / photosynthesis inhibition Inhibits PPO enzyme / chlorophyll Pigment synthesis Plant enzyme inhibition / EPSPS Plant enzyme inhibition / ALS Plant enzyme inhibition / ALS Plant enzyme inhibition / ALS Auxin mimic / plant growth regulation

15 Herbicide Translocation and Selectivity Herbicide Translocation Selectivity 2,4-D Systemic Selective Bispyribac-sodium Systemic Broad spectrum Carfentrazone-ethyl Contact Selective Copper Contact Broad spectrum Diquat Contact Broad spectrum Endothall Contact Selective (Timing) Flumioxazin Contact Broad spectrum Fluridone Systemic Selective (Rate) Glyphosate Systemic Broad spectrum Imazamox Systemic Selective Imazapyr Systemic Broad spectrum Penoxsulam Systemic Selective (Rate) Triclopyr Systemic Selective

16 Herbicide Degradation & Half-life Herbicide Degradation ½-life in water (days) 2,4-D Microbial, Photolysis 7 to 48 Bispyribac-sodium Microbial ~ 30 Carfentrazone-ethyl Hydrolysis, Photolysis 3 to 8 (ph dependent) Copper Chemically bound Hardness dependent Diquat Adsorption, Photolysis 1 to 7 Endothall Microbial 4 to 7 Flumioxazin Photolysis, Microbial 3-5 d (ph 5) to min (ph 9) Fluridone Photolysis, Microbial 20+ Glyphosate Adsorption, Microbial 14 Imazamox Microbial, Photolysis 7 to 14 Imazapyr Photolysis, Microbial 2 to 4 Penoxsulam Photolysis, Microbial 15+ Triclopyr Photolysis, Microbial 0.5 to 3

17 Aquatic Herbicide Toxicity Herbicide Typical Rates in H 2 O (ppm) Bluegill 96-hr LC-50 (ppm) 2,4-D 0.5 to Bispyribac-sodium to > 100 Carfentrazone-ethyl 0.2 >5000 Copper 0.2 to 1.0 Soft water: 0.88, Hard water: 7.3 Diquat 0.1 to Endothall 0.3 to 3.0 Dipotassium salt: 343, Alkylamine salt: 0.94 Flumioxazin 0.1 to 0.4 >21 Fluridone to Glyphosate NA >1000 Imazamox 0.05 to >100 Imazapyr NA >100 Penoxsulam 0.01 to Triclopyr 0.75 to

18 Copper (1950 s) Target weeds: hydrilla, planktonic algae, filamentous algae, chara/nitella, coontail, milfoil spp., pondweed spp. Subsurface application Typical use rates: 0.5 to 1 ppm Max concentration: 1 ppm Restrictions Label changes are coming for copper products Due to multiple manufacturers, follow all label instructions regarding rate, adjuvants, application technique, and use restrictions. Check with appropriate regulatory agencies before purchasing or applying pesticides to the water. Always Follow The Label!

19 2,4-D (1959) Target weeds: Eurasian watermilfoil, water hyacinth, coontail, waterlily, parrotfeather Subsurface and foliar application Typical use rates: 0.5 to 4 ppm, 2 to 4 lb ae/a Max concentration and rate: 4 ppm, 4 lb ae/a Restrictions Potable water intake: 5 to 14 days (1 to 4 ppm) Drinking water setback: 600 to 2400 ft (1 to 4 ppm) Swimming (butoxyethanol ester only): 24 hr Drinking: concentration <70 ppb Labeled crop irrigation: none Unlabeled crop irrigation: concentration <100 ppb Due to multiple manufacturers, follow all label instructions regarding rate, adjuvants, application technique, and use restrictions. Check with appropriate regulatory agencies before purchasing or applying pesticides to the water. Always Follow The Label!

20 Endothall (1960) Target weeds: hydrilla, coontail, pondweed spp., milfoil spp. Subsurface application Typical use rates: 0.3 to 3 ppm Max concentration: 5 ppm Partial lake use Restrictions Livestock consumption 7 day for up to 0.5 ppm 14 day for up to 4.25 ppm 25 day for up to 5 ppm Due to multiple manufacturers, follow all label instructions regarding rate, adjuvants, application technique, and use restrictions. Check with appropriate regulatory agencies before purchasing or applying pesticides to the water. Always Follow The Label!

21 Diquat (1962) Target weeds: hydrilla, coontail, salvinia spp., duckweed spp., water hyacinth, waterlettuce Subsurface and foliar application Typical use rates: 0.1 to 0.37 ppm Max concentration: 0.37 ppm Partial lake use Restrictions Drinking: 1 to 3 days Livestock: 1 day Turf and ornamental landscape irrigation: 1 to 3 days Food crop and production, ornamental irrigation: 5 days Fishing and swimming: none Due to multiple manufacturers, follow all label instructions regarding rate, adjuvants, application technique, and use restrictions. Check with appropriate regulatory agencies before purchasing or applying pesticides to the water. Always Follow The Label!

22 Glyphosate (1977) Target weeds: salvinia spp., alligatorweed, cattail, water hyacinth, waterlettuce, torpdeograss, cogongrass, phragmites Foliar application Typical use rates: 3 to 6 pints/a Max rate: 7.5 pints/a or 2% solution Restrictions Potable water intake: <700 ppb within ½ mile Others: none Due to multiple manufacturers, follow all label instructions regarding rate, adjuvants, application technique, and use restrictions. Check with appropriate regulatory agencies before purchasing or applying pesticides to the water. Always Follow The Label!

23 Fluridone (1986) Target weeds: hydrilla, salvinia spp., pondweed spp., Eurasian watermilfoil Subsurface application Typical use rates: to 0.03 ppm Max concentration: 0.15 ppm Long-term exposures required (60+ days) Whole-lake or large scale use Restrictions Potable water intake: <20 ppb within ¼ mile Irrigation: 7 to 30 days Due to multiple manufacturers, follow all label instructions regarding rate, adjuvants, application technique, and use restrictions. Check with appropriate regulatory agencies before purchasing or applying pesticides to the water. Always Follow The Label!

24 Triclopyr (2002) Target weeds: milfoil spp., water hyacinth, waterlily, alligatorweed Subsurface and foliar application Typical use rates: 0.75 to 2.5 ppm, 1 to 3 lb ae/a Max concentration and rate: 2.5 ppm, 6 lb ae/yr Restrictions Potable water/drinking: see label for specifics Labeled crop irrigation: none Irrigation: 120 days or <1 ppb Due to multiple manufacturers, follow all label instructions regarding rate, adjuvants, application technique, and use restrictions. Check with appropriate regulatory agencies before purchasing or applying pesticides to the water. Always Follow The Label!

25 Imazapyr (2003) Target weeds: duckweed, alligatorweed, cattail, parrot feather, water hyacinth, waterlettuce, torpdeograss, cogongrass, malaleuca, phragmites Foliar application Typical use rates: 2 to 6 pints/a Max rate: 6 pints/a (1.5 lb ai/a) or 5% solution Restrictions Potable water intake: do not use within ½ mile Irrigation: 120 days or <1 ppb Due to multiple manufacturers, follow all label instructions regarding rate, adjuvants, application technique, and use restrictions. Check with appropriate regulatory agencies before purchasing or applying pesticides to the water. Always Follow The Label!

26 Carfentrazone-ethyl (2004) Target weeds: water lettuce, duckweed, watermeal, giant salvinia Subsurface and foliar application: ph dependent Max concentration and rate: 0.2 ppm, 0.2 lb ai/a Restrictions Potable water intake: within ¼ mile or <200 ppb Irrigation: 14 days if >20% treated or 1 day if <20%; concentrations <1 ppb Drinking: 1 day if >20% treated Livestock: 1 day if >20% and concentrations <200 ppb Due to multiple manufacturers, follow all label instructions regarding rate, adjuvants, application technique, and use restrictions. Check with appropriate regulatory agencies before purchasing or applying pesticides to the water. Always Follow The Label!

27 Penoxsulam (2007) Target weeds: hydrilla, salvinia spp., water hyacinth, duckweed spp., Eurasian watermilfoil, egeria Subsurface and foliar application Typical use rates: 0.01 to 0.04 ppm Max concentration: 0.15 ppm Long-term exposures required (60+ days) Whole-lake or large scale use Restrictions Potable water intake: <20 ppb within ¼ mile Irrigation restrictions dependent upon crop Due to multiple manufacturers, follow all label instructions regarding rate, adjuvants, application technique, and use restrictions. Check with appropriate regulatory agencies before purchasing or applying pesticides to the water. Always Follow The Label!

28 Imazamox (2008) Target weeds: hydrilla, alligatorweed, common salvinia, water hyacinth, water lettuce, curlyleaf pondweed Subsurface and foliar application Typical use rates: to ppm Max concentration: 0.5 ppm Whole-lake or large scale use Restrictions Potable water intake: <50 ppb within ¼ mile Do not irrigate greenhouses, nurseries, or hydroponics Irrigation: concentration 50 ppb Due to multiple manufacturers, follow all label instructions regarding rate, adjuvants, application technique, and use restrictions. Check with appropriate regulatory agencies before purchasing or applying pesticides to the water. Always Follow The Label!

29 Flumioxazin (2010) Target weeds: hydrilla, Eurasian watermilfoil, sago pondweed, salvinia spp., water lettuce, alligatorweed Subsurface and foliar application: ph dependent Typical use rates: to ppm or (6-12 oz./a buffer spray solution to < 7 ph) Max concentration: ppm Whole-lake or large scale use Restrictions Do not apply to waters used for crayfish farming 5 day Irrigation restriction Due to multiple manufacturers, follow all label instructions regarding rate, adjuvants, application technique, and use restrictions. Check with appropriate regulatory agencies before purchasing or applying pesticides to the water. Always Follow The Label!

30 Bispyribac-sodium (2011) Target weeds: hydrilla, Eurasian watermilfoil, salvinia spp., water hyacinth, water lettuce, alligatorweed Subsurface and foliar application Typical use rates: to ppm (1-2 oz./a) Max concentration: ppm Whole-lake or large scale use Restrictions Treated water can not be used for livestock until 1 ppb Do not apply to waters used for crayfish farming Irrigation restriction for food and ornamental 1 ppb Due to multiple manufacturers, follow all label instructions regarding rate, adjuvants, application technique, and use restrictions. Check with appropriate regulatory agencies before purchasing or applying pesticides to the water. Always Follow The Label!

31 Defining Use Patterns for Herbicide Applications Concentration exposure time relationships (CET) Herbicide applications for submersed plant control are impacted by: The concentration of the herbicide in water that surrounds the target plant The length of time a target plant is exposed to dissipating concentrations of that herbicide

32 Concentration and exposure time relationships Endothall v EWM (Netherland et al. 1991) Triclopyr v EWM (K. Getsinger, USAERDC)

33 Other Factors Influencing Aquatic Weed Control ph (carfentrazone, flumioxazin) Acid < 7=neutral > basic Hardness/alkalinity (copper) Soft < 50 ppm CaCo 3 >Hard Turbidity (diquat) Organic Inorganic

34 Other Factors Influencing Aquatic Thermal Stratification Drop hoses Handgun Pellet formulations Weed Control Water flow Herbicide placement Slow release formulations Metered/sequential applications Growth stage/time of year/plant maturity Adequate herbicide coverage/distribution

35 Site Specific Water Exchange Characteristics Utilizing CET relationships & application timing to maximize herbicide efficacy Water Discharge for 7/23/2009 Flowing water on regulated reservoirs presents unique challenges Water Discharge in cfs :00 AM 3:00 AM 5:00 AM 7:00 AM 9:00 AM 11:00 AM 1:00 PM 3:00 PM 5:00 PM 7:00 PM 9:00 PM 11:00 PM Water Discharged Noxon Rapids Reservoir, MT

36 Understanding How Water Exchange Affects Applications

37 Plant Growth Stage: Curlyleaf Pondweed Plant Height from Lake Bottom to Water Surface (cm) Curlyleaf Pondweed Ice Cover Flowering and Turion Formation Target Management Plant Senescence (Only Turions Remain) Target Management Turion Sprouting 0 Jan Mar May Jul Sep Nov Jan Native Plant Growth

38 Maximizing Selectivity The susceptibility or tolerance of different plants to a herbicide Concentration/rate, absorption, translocation, metabolism, conjugation, accumulation & secretion Timing can have a major impact on selectivity Different species have maximum growth at different times E.g. Curlyleaf pondweed Species composition is very important in herbicide selection Lack of impacts to non-targets may be equally or more important than impacts on the target

39 Weed Shifts Related to Herbicides In general, management (cropping) systems impose very high selection pressures on weed communities, resulting in weed population shifts (Owen (2008) These shifts are towards populations with adaptive traits that overcome management tactics and subsequently increase in density High level of seed production = High genetic variability Biotypes that are more competitive Ex. Using auxin herbicides to manage Eurasian watermilfoil, curlyleaf pondweed fills the niche vacated by Eurasian watermilfoil

40 Weed Shifts Related to Herbicides Even when using broad spectrum herbicides, not all species will respond similarly at the rates and exposure time used

41 Hardin 1985 every good pesticide selects for its own failure Case New Holland

42 Herbicide Resistance Shift in the amount (rate) required to achieve a similar level of control Complete lack of control

43 Herbicide Resistance A shift in the population of a once susceptible biotype to a biotype that is resistant to normal application rates SO HOW DOES IT HAPPEN?!

44 Selectivity Selectivity Selectivity One plant survives and then Source:J. L. Gonsolus. Herb. Res. Weeds. 1998

45 Types of Resistance Cross resistance: weed is resistant to >1 herbicide with the same mode of action Multiple resistance: weed is resistant to >1 herbicide with different mode action

46 Mechanisms of Resistance/Tolerance X Herbicide X not absorbed X Sequestered in vacuole X does not bind to enzyme Y X metabolized to Z Y1

47 Target site Resistance Source: J. L. Gonsolus. Herb. Res. Weeds. 1998

48 Single site of action What Enhances Chances? Multiple applications per season, persistence of herbicide in environment Repeated use of same material Stand alone treatments Low, sublethal rates Some plants are just more likely highly outcrossed species high genetic plasticity, vegetativeness

49 Super Weeds? The herbicide did not cause the mutation, it was preexisting in the population The repeated use has selected for an alternative biotype

50 Herbicide Resistance (Aquatics) Landoltia resitant to diquat Hydrilla verticillata resistant to fluridone and suspected resistance to endothall Myriophyllum spicatum suspected fluridone resistance Hybrid milfoil??? Others???

51 Consequences of Resistance May show cross resistance to other herbicides Increasing herbicide rates increase costs/acre decrease in selectivity postponing the inevitable Change control tactics, herbicides increase costs/acre, fuel costs decrease in selectivity

52 Resistance Management Rotate herbicides with different modes of action Tank mix multiple modes of action Less convenient? Increase cost? Increase crop injury risk? Reduce the window of application?? IPM approach Biological Mechanical Physical

53 Questions to Ask Prior to Applying What is the Major Use of the Water? Irrigation, retention, recreation, multipurpose Where Does the Treated Water Go? What is downstream and how fast does it get there Are Fish an Important Resource? Pay attention to water temperature, DO, plant mass Is the site susceptible to rapid turnover? Flow, significant rain event What non-target plant species are present? Herbicide selection, determine time of year to treat

54 Other Resources UNIVERSITY Center for Aquatic and Invasive Plants aquat1.ifas.ufl.edu Mississippi State University GRI MSU Extension Service msucares.com/pubs/publications/p1532aquati c.pdf North Carolina State University default.asp FOUNDATION Aquatic Ecosystem Restoration Foundation PROFESSIONAL SOCIETY Aquatic Plant Management Society North American Lake Management Society GOVERNMENT Aquatic Plant Control Research Program USGS Aquatic Nonindigenous Species Site nas.er.usgs.gov National Biological Information Infrastructure invasivespecies.nbii.gov

55 Acknowledgements Dr. Chris Mudge Dr. Greg MacDonald Justin Nawrocki

56 Contact Information Ryan Wersal, PhD Aquatic Plant Scientist Lonza Microbial Control Alpharetta Innovation and Technology Center 1200 Bluegrass Lakes Pkwy Alpharetta, GA Ph (678) Cell (770) Fax (678)