1. Integrated Pest Management -- Weeds Basic Training for Agents University of Kentucky February 2006 J. D. Green and J. R. Martin Extension Weed Science Plant and Soil Science

2. What is a WEED A plant growing where it is not wanted (a plant out of place). –Plants are considered weeds when they interfere with the activities of man or his welfare. Plants which have adverse economic, health, and/or aesthetic consequences. –Weeds often introduced species Johnsongrass (Euroasia) Kudzu (Japan) Japanese Knotweed (Asia) (#11)

3. Weed Classification Annuals : (life cycle in one season) –Warm Season Foxtails, large crabgrass, broadleaf signalgrass Cocklebur, Eastern black nightshade, giant ragweed, ivyleaf morningglory, smooth pigweed, lambsquarters –Cool Season Italian ryegrass, little barley Common chickweed, henbit, purple deadnettle Biennials: (life cycle up to 2 seasons) Musk thistle (Nodding thistle) Perennials: (life cycle more than 2 seasons) Johnsongrass, yellow nutsedge, honeyvine milkweed, dandelion, wild garlic (#11)

4. Reproduction Methods of Weeds Perennials: SIMPLE (no spreading propagules) Dandelions, Curly dock SPREADING (have vegetative propagules) –Root Buds; Creeping Rootstocks Honeyvine milkweed, Canada thistle –Rhizomes Johnsongrass –Bulbs Wild garlic, Yellow nutsedge –Tubers Yellow nutsedge (#12)

5. Factors Affecting Weed-Crop Competition Row Spacing Crop Population Weed Species & Density Duration of Competition Weed Distribution (#13)

6. Impact of Weed Species on Crop Yield  Cocklebur  Giant Ragweed  Velvetleaf  Morningglory  Lambsquarters  Pigweeds  Johnsongrass  Crabgrass  Foxtail more less competitiveness

7. Weed Density Crop Yield (%) Impact of Weed Density on Crop Yield Influenced by: environment time of weed emergence crop canopy (row spacing)

8. Weeks After Planting Crop Yield (%) Critical Period

9. Part III: Integrated Pest Management for Weeds Competency Area 3. – Pest Mangement Tactics Non-pesticide pest management tactics Discussion No. 20-21, 23-25

10. Weed Management Tactics Non-Pesticide Methods  Prevention  Mechanical  Cultural  Biological

11. Prevention Plant weed-free seed –Kentucky seed law (noxious weed seed) Eastern black nightshade Balloonvine Avoid introduction of unwanted plants –Certified seed vs Bin run seed Sicklepod Spurred Anoda Keep field borders clean (#20)

12. Mechanical Controls 1)Tillage practices: –Primary tillage moldboard plow chisel plowing –Secondary tillage disc / harrow field cultivator –Selective cultivation Cultivator Conservation-till cultivator (#23)

13. JDG

14. Common Pokeweed Control (%) with and without Cultivation in No-Tillage Corn at Three Locations 1996 (4 WAT) Woodford (#1) Woodford (#2) Hardin Co.

15. Mechanical Controls 2)Hand weeding:  High value crops Tobacco Vegetables Organic grown crops 3)Mowing: –Pasture weeds (#23)

16. Cultural Practices Know the Field History -- Look for problematic weeds in the past Cropping Sequence / Crop Rotations -- eg. Johnsongrass Variety/Hybrid Selection -- use of herbicide tolerant crops Seed or Plant Source -- certified seed vs bin run seed (#24)

17. Cultural Practices Tillage System -- impact on perennial weeds Residue Management -- impact on soil-applied herbicides Planting Date -- eg. Johnsongrass Plant Population / Row Spacing -- crop canopy closure impact on weed/crop interference (eg. Less yield loss from cocklebur in narrow-row soybean) (#24)

18. Biological Controls  Musk Thistle control  Thistle-head weevil  Thistle rosette weevil  Grazing pastures  Cattle  Goats (#25)

19. Part III: Integrated Pest Management Competency Area 3. – Pest Mangement Tactics Herbicide Management Discussion No. 27 – 32

20. Weed Management Tactics Pesticide Control Methods  Herbicide Selection and Use  Crop Genetics  Herbicide Tolerant Crops

21. Factors that Affect Herbicide Selection and Use in Kentucky Proper Weed Identification (Life Cycle) Incidence and Severity of the Pest (Weed) Past History in the Field Potential for Weed Resistance Weed Stage of Development  Before weed emergence  After weed emergence (size & growth stage) Crop Stage of Development (#28)

22. Factors that Affect Herbicide Selection and Use in Kentucky Effectiveness against the weed(s) Persistence  Beneficial for weed control longevity  Problem for crop rotations Chemical & Physical Properties of the Pesticide (liquid vs dry) Mammalian Toxicity (paraquat vs glyphosate) Environmental Hazard  Ground and/or surface water impacts (#28)

23. Factors that Affect Herbicide Selection and Use in Kentucky Method of Pesticide Application  Preplant Foliar, Preplant Incorporated, Preemergence (soil- applied), Postemergence Soil Characteristics  Soil type, texture, soil pH  Application rates, Persistence, etc. Pesticide Availability & Label Restrictions Economics Public Concerns -- Potential environmental impact -- Biotechnology derived crops (GMO’s) (#28)

24. Weed Management Decisions Economics Environment Efficacy

25. Methods of Herbicide Application (Benefits & Limitations)  Early Pre-Plant  Spring (2 to 4 weeks before planting)  Fall (previous year)  Preplant Incorporated  Preemergence  Postemergence  Postemergence Directed (#36)

26. Factors Influencing Crop Injury Caused by Pesticides (Herbicides)  Crop/variety sensitivity -- spraying the wrong field -- crop growth stage  Weather  Crop under stress conditions  Persistence -- rotational crop concerns  Rate and Formulation  Method of Application (Timing)  Incompatibilities of Pesticides  Tank mixture combinations  Herbicide / Insecticide interactions (#27)

27. Effect of Plant Growth Stage and Influence of Environmental Factors on Weed Control and Herbicide Injury  Smaller weeds  easier to control  Later stages of crop growth  More likely for crop injury to occur  Environmental stress  Less weed control possible  Increase potential for crop injury  Air Temperature oParaquat vs Glyphosate (Gramoxone) (Roundup) (#37)

28. Types of Herbicide Interactions  Additive  Synergistic  Antagonistic (#31)

29. Use of Adjuvants / Additives  Enhance biological activity or improves pesticide performance Surfactants Sticker-spreaders Oils Salts or Fertilizers  Minimizes handling and application problems Compatibility agents Foam retardant Buffer agents Drift control agents (#29)

30. I. Activator Adjuvants Surfactants Phytobland Oils Oil-surfactant mixtures: –Crop Oil –Crop Oil Concentrates –Methylated Seed Oils (MSO) Silicone derivatives Nitrogen Fertilizers

31. Surfactant  Surfactant = surface active agent Non-Ionic (most common type used) Anionic Cationic  Typically marketed as liquids that contain 50% to 100% active ingredient  octoxynol, dooxynol, nonoxynol, oxysorbic  Reduce surface tension of water droplets; greater coverage of leaf surface

32. II. Utility Modifiers of Herbicidal Sprays Used to alter undesirable characteristics of herbicide mixtures or to alter the spray mixture to enhance or stabilize the spray mixture Antifoam Agents Compatibility Agents Buffering Agents Drift Control Agents

33. Genetic Herbicide Tolerant Crops (#21)  Selection: -- from natural populations within a crop species -- of herbicide tolerant mutants within a cultivar at the cell or whole plant level  Insertion of genes conferring tolerance

34. Herbicide Tolerant Crops [ Selection Method ]  IMI-tolerant corn hybrids (1992) »Imidazolinone Resistant (IR) and Tolerant (IT) corn hybrids »eg. LIGHTNING on Clearfield-corn hybrids  STS soybeans (1995) »Sulfonylurea Tolerant Soybean »Synchrony STS  POAST resistant corn (1995) »sethoxydim resistance »Poast Protected hybrids (PP-corn)

35. Herbicide Tolerant Crops [ Insertion Method ]  ROUNDUP READY soybean (1996) »glyphosate tolerance »Introduced gene that increases production of EPSP synthase  LIBERTY LINK corn (1997)  LIBERTY LINK soybean (1998) »glufosinate-ammonium (i.e. phosphinothricin) »PAT gene inserted into the crop  ROUNDUP READY corn (1998) »glyphosate tolerance

36. Herbicide Tolerant Crops Advantages / Benefits  Less risk of crop injury  Fewer carry-over problems with herbicides?  Broader spectrum of weed control  Use ‘environmentally friendly’ herbicides  Less expensive ?? (#21)

37. Roundup Ready TM soybeans High Acceptability by Crop Producers  Convenience  one herbicide / rate selection / timing?  Clean fields  broad spectrum of weeds controlled  Ability to tackle problem weeds  Less intense scouting ??

38. Concerns with Herbicide Tolerant Crops  Herbicide tolerant crop may transfer resistance to related species (eg. Canola / mustards)  Herbicide tolerant crop may become a weed  Lead to fewer alternative weed control practices  More dependence on herbicides  Public acceptance or non-acceptance

39. Use of Herbicide Tolerant Crops Will they help prevent weed resistance?  In some situations, they may provide an opportunity to rotate herbicides with different “modes of activity”  On the other hand, they can broaden the opportunity to use the same herbicide in both corn and soybeans

40. Part III: Integrated Pest Management Competency Area 3. – Pest Mangement Tactics Herbicide Persistance Discussion No. 34 – 37

41. Herbicide Persistence Desirable Weed control Undesirable rotational crop injury environmental contamination (#34)

42. Persistence is a function of herbicide dissipation rate Herbicide Rate Application Time Soil type  organic matter  Clay (type & amount) Soil pH  chemical degrade.  microbial degrade. Adsorption Soil temperature Soil moisture Distribution in soil Repeat applications Cropping sequence  Crop/variety sensitivity Herbicide Formulation

43. Herbicide Persistence and Recrop Interval Time Herbicide Concentration Recrop tolerance concentration Adverse: (drought, low temperature, extreme pH) Optimum: (normal moisture, temp, pH)

44. Persistence of Herbicides Under Kentucky Conditions HerbicideHalf-life (days) Dual (metolachlor) 11 Lasso (alachlor) 5 Frontier (dimethenamid) 3 Surpass (acetochlor) 3 Princeton, KY. 1995. Crider silt loam. (#35)

45. Labeled Rotational Crop Intervals for Soil-Applied Herbicides -------------(months, etc)------------ # Includes products that contain Atrazine (i.e. Bicep II, FulTime, Harness Xtra, etc.) * Potential injury to rotational crop if conditions are extremely dry

46. Labeled Rotational Crop Intervals for Soil-Applied Herbicides -------------(months)-------------- # Waiting period may be longer for high pH soils.

47. Recrop Interval* for Canopy pH <7.0 Field corn 10 Tomato 10 Cucumber 10 Sweet corn & all others 18 * Months pH >7.0 18 30

48. Part III: Integrated Pest Management Competency Area 4 & 5. – Pesticide Stewardship Ground and Surface Water Spray Drift and Volatilization

49. Ground and Surface Water Advisories [Herbicides with Water Quality Statements] Rate Restrictions – Maximum rates allowed: Soil Texture Based on tillage system / Previous plant residue / Erodibility * Depth of water table (eg. Balance) Setbacks – Do not mix or load within 50 ft of wells, rivers, intermittent streams, lakes, or reservoirs – Products should not be applied within 50 ft of wells or sink holes; within 66 ft of where field surface water enters streams or rivers; or within 200 ft around lakes or reservoirs * * Atrazine and herbicide products containing atrazine: (AAtrex, Bicep II Magnum, Degree Xtra, Harness Xtra, etc.) (#42,43,45)

50. Safe Drinking Water Act (SDWA) - 1992 Required public water utilities to begin monitoring for atrazine, and other substances regulated by SDWA (by January 1995) A water system is considered out of compliance if the running annual average is above the Maximum Contaminant Level (MCL) – Atrazine MCL = 3 ppb (3 micrograms per liter) If atrazine is detected above the MCL, water utilities are required to notify the public and take action to reduce levels below MCL

51. Atrazine Re-Registration Update January 2003  EPA issued an Interim Re-registration Eligibility Decision (IRED) to conduct an innovative monitoring program on community water systems that are considered to be most vulnerable to atrazine (40 indicator watersheds)  Under an Memorandum of Agreement with Syngenta, atrazine will be intensively monitored in the most vulnerable watersheds where detections exceed the MCL. If established safety standards are exceeded after remediation efforts, the use of atrazine will be prohibited in that watershed.  Revised cancer classification Atrazine “not likely” to be a human carcinogen Addendum - October 2003  No scientific link between atrazine and prostate cancer  Available studies do not provide sufficient evidence to show a consistent, reproducible effect of atrazine on amphibian development

52. Situation - Kentucky Two municipal water systems in Kentucky require intensive monitoring -- – Atrazine exceeded the MCL level (3 ppb) for three or more consecutive months (sampling period 1999 – 2002) – These small municipal lakes used for public drinking water sources are fed by small watersheds; thus, atrazine use practices more easily mitigated in surrounding crop land Two additional community water systems are being intensively monitored because the atrazine concentration exceeded the MCL at one sampling time during the 2003 calendar year – One sample site is part of a large watershed

54. Spray Drift / Volatilization  Spray Volume  Weather Conditions  Pesticide Formulation  Eg. 2,4-D Ester vs 2,4-D Amine  Additives  Nozzle Height  Droplet Size  Spray Pressure (#49)