1 / 47

Unit 2: Weed Control for Corn, SB, & Sorghum

Unit 2: Weed Control for Corn, SB, & Sorghum. Unit 2: Weed Control for Corn, SB, & Sorghum. Unit 2 Objectives: Awareness of safety, proper use, and label warnings of pesticides Understanding of herbicide application methods Preemergence application Postemergence application

kermit
Download Presentation

Unit 2: Weed Control for Corn, SB, & Sorghum

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Unit 2: Weed Control for Corn, SB, & Sorghum

  2. Unit 2: Weed Control for Corn, SB, & Sorghum • Unit 2 Objectives: • Awareness of safety, proper use, and label warnings of pesticides • Understanding of herbicide application methods • Preemergence application • Postemergence application • Discussion of the effect of various tillage methods and its relationship to chemical efficacy

  3. Unit 2: Weed Control for Corn, SB, & Sorghum • Precautions • Risks and benefits must be evaluated • Crops, people, & environment • Use should be restricted to minimize exposure • Current Label • Herbicides classified as Restricted Use Pesticides must be applied by a certified applicator • Chemical may be toxic or pose environmental concerns

  4. Unit 2: Weed Control for Corn, SB, & Sorghum • Degree of toxicity indicated on the label by a Signal Word • Danger-Poison and Danger – high toxicity hazard • Warning – moderate toxicity • Always use personal protective equipment as recommended on the label for safety • Be aware of drift potential, especially near residential areas • Environmental Hazards • Groundwater advisories must be observed • Toxicity of fish/wildlife will be listed on the label

  5. Unit 2: Weed Control for Corn, SB, & Sorghum • Proper Herbicide Use • Apply only to approved crops • Use proper rates • Apply at the proper time • Proper use will decrease risk of illegal residual, and environmental pollution • Be aware of proper harvesting or grazing withholdings

  6. Unit 2: Weed Control for Corn, SB, & Sorghum • Proper Equipment Use • Spray tanks should be clean and free of other residues • Especially critical when spraying postemergence herbicides • Sprayer should be correctly calibrated and adjusted before adding herbicide to the tank • Follow recommendations on the label

  7. Unit 2: Weed Control for Corn, SB, & Sorghum • Drift Precautions • Apply on calm or light wind days only • Be aware of wind direction and residential areas, ornamental crops, etc. • Some chemicals are very mobile, and effects can be observed far from the application site • Protecting the Crop • Do not apply to stressed crops

  8. Unit 2: Weed Control for Corn, SB, & Sorghum • Understand crop sensitivities • Crop size • Climatic conditions • Previous injury from diseases, insects, or other chemicals • Proper Recropping Interval • Understand chemical carryover and how it can affect the next crop • Soil texture, organic matter, soil pH all may affect persistence

  9. Unit 2: Weed Control for Corn, SB, & Sorghum • Proper Storage of Herbicides • Store in original, labeled containers in a secure place • Keep away from kids, livestock, etc. • Proper Disposal • Pressure wash, or triple rinse containers • Properly cleaned containers may be recycled, or be acceptable in some landfills • Mini-bulk returnable containers are desirable • Use caution if you are going to burn

  10. Unit 2: Weed Control for Corn, SB, & Sorghum • Cultural and Mechanical Weed Control • Practices that aid in weed control • Adequate seedbed preparation • Adequate fertilization • Crop rotation • Proper planting date • Optimal row width • Optimal seeding rate

  11. Unit 2: Weed Control for Corn, SB, & Sorghum • Planting in relatively warm soil helps the seed emerge quickly and compete with emerging weeds • 1st 3-5 wks. are critical for good weed control in corn and soybeans • Crops tend to compete very well after this point • Narrow rows can help • Squeezes out weeds • Puts more pressure on herbicides for weed control • If control is inadequate it is better to leave room for cultivation

  12. Unit 2: Weed Control for Corn, SB, & Sorghum • Row cultivation • Can control when weeds are small • Smothers weeds • Careful adjustment to minimize crop injury • May not be necessary if herbicide controls weeds adequately, and no aeration is needed

  13. Unit 2: Weed Control for Corn, SB, & Sorghum • Herbicide Incorporation • Reasons for incorporation • Minimizes depending on rainfall • May improve control of some weeds • Minimize surface losses • Distribute herbicide uniformly in the top 1-2” of soil • Suggested depth of operation for proper incorporation is 3-4”

  14. Unit 2: Weed Control for Corn, SB, & Sorghum • May require two passes for best operation • Second pass should be at angle and no deeper than first pass • Proper application and incorporation minimizes crop injury and carryover problems • Uniform distribution depends on type of equipment, depth of operation, speed of operation, soil texture, soil moisture • Placement deeper than 1-2” may dilute the herbicide and reduce effectiveness

  15. Unit 2: Weed Control for Corn, SB, & Sorghum • Field Cultivators • At least 3 rows w/ sweeps • 7” or less spacing between sweeps • Level and operate at 3-4” depth • Minimum 5 mph ground speed • Tandem Disks • Blade diameter of 20” or less • 7-9” blade spacing • 3-4” operating depth

  16. Unit 2: Weed Control for Corn, SB, & Sorghum • 4-6 mph ground speed • Want to move soil full width of the blade space • Slower speed or lack of leveling device can cause streaking of herbicide • Combination Tools • Advantage is they can handle more surface residue • More uniform one-pass incorporation than disk or field cultivator • No better than two passes w/ one of the other tools

  17. Unit 2: Weed Control for Corn, SB, & Sorghum • Chemical Weed Control • Several factors to consider when planning weed control: • Soil • Tillage program • Crops • Weed problems • Management operations

  18. Unit 2: Weed Control for Corn, SB, & Sorghum • Herbicide performance depends on: • Weather • Proper selection • Application • Minimize crop injury by using proper timing, application rates, uniform spraying • Damaged crops are more prone to disease

  19. Unit 2: Weed Control for Corn, SB, & Sorghum • Unfavorable conditions • Cool, wet weather • Delayed crop emergence • Deep planting • Seedling disease • Poor physical condition of soil • Poor quality seed

  20. Unit 2: Weed Control for Corn, SB, & Sorghum • Next season’s plans must also be considered when selecting a herbicide program • Corn/SB herbicides may have restrictive recropping intervals • Check label for restrictions • Can vary depending on the number of applications, timing, weather, soil, pH, etc. • Ex. Atrazine restricts planting wheat after corn

  21. Unit 2: Weed Control for Corn, SB, & Sorghum • Persistent corn herbicides of concern for SB • Atrazine • Clopyralid (Stinger) • Prosulfuron • Persistent SB herbicides of concern for corn • Imazaquin (Scepter) • Chlorimuron (Classic)

  22. Unit 2: Weed Control for Corn, SB, & Sorghum • Weed Resistance to Herbicides • Like insects, weeds have the ability to become resistant • Weeds that have become resistant to different chemicals • Pigweed, waterhemp, lambquarters, ragweed, cocklebur, and many others • Management recommendations to help prevent herbicide resistance: • Scout fields regularly & identify resistant weeds, keep records of weed populations to monitor/restrict their spread

  23. Unit 2: Weed Control for Corn, SB, & Sorghum • Rotate herbicides w/ different sites of action • No more than two applications of the same herbicide in the same or successive years on the same weed w/ same site of action • Use other strategies for weed control • Especially critical when using herbicide tolerant crops • Use multiple sites of action • Tank mix • Premix • Sequential applications

  24. Unit 2: Weed Control for Corn, SB, & Sorghum • If practical use rotary hoeing and cultivation to control resistant weeds • Hand weeding may be needed • Herbicide resistant weeds can spread from nearby highways, railroads, utility areas etc. where total vegetation control may be used • Herbicide Combinations • In tank mixes, premixes, or sequential applications • Can control more weed, reduce carryover, reduce crop injury

  25. Unit 2: Weed Control for Corn, SB, & Sorghum • May be able to split apply (same herbicide, two apps.) or sequential apply (two apps., different herbicides) • Many combinations sold as premixes • Harness Xtra • Lightning • Canopy XL • Alleviates some compatibility problems associated w/ tank mixing • Some are tank-mixed • Allows adjustment for local problems • Weed pressures • Soil conditions

  26. Unit 2: Weed Control for Corn, SB, & Sorghum • Read and follow all restrictions when tank mixing • Problems may occur when mixing emulsifiable concentrates w/ suspendible herbicides (liquid-flowable, dry-flowable) • Proper mixing can minimize the difficulties (agitation, carriers, etc.) • Must be cautious of accumulations in tank – thoroughly clean after application

  27. Unit 2: Weed Control for Corn, SB, & Sorghum • Herbicide Rates • Rates vary • Time & method of application • Soil conditions • Tillage system • Weed pressure • Rates of herbicides in combination often are lower than the same chemical used alone

  28. Unit 2: Weed Control for Corn, SB, & Sorghum • Soil-applied herbicides • Texture of the soil • Amount of organic matter • Specific recommendations for sandy soils • Postemergence rates • Size of the weed • Species of weed • Rates listed are broadcast rates • Adjustment will be needed if a different method is used • Formulations w/ different combinations may vary amount of active ingredient

  29. Unit 2: Weed Control for Corn, SB, & Sorghum • Postemergence Herbicide Principles • Efficacy relies on foliar activity more than soil action • Some may have both modes of action • Rates and timing based on: • Weed size • The smaller the weed, the lower the rate • Weather • Penetration & action is higher in warmer weather and higher humidity • Rainfall within 30 min to 6 hrs. can reduce effect

  30. Unit 2: Weed Control for Corn, SB, & Sorghum • Contact herbicides require more complete coverage • Coverage increases as water volume and spray pressure are increased • Nozzles that produce small droplets also increase coverage • Usually 10-40g of water/ac. for ground application • 30-60 psi suggested • Flat-fan • Hollow-cone nozzles • May be more drift risk

  31. Unit 2: Weed Control for Corn, SB, & Sorghum • Crop size limitations often indicated on the label • Minimize crop injury • Maximize weed control • Weeds smaller than the crop • Basal-directed sprays may help minimize crop injury • Place more herbicide on the weed • Weeds taller than the crop • Rope-wick • Sponge app. • Place herbicide on weed instead of crop

  32. Unit 2: Weed Control for Corn, SB, & Sorghum • Herbicide Adjuvants • Crop-oil concentrate (COC) • Spread herbicide across foliar surface • Keep surface moist longer • Aid penetration to the cuticle • Increases mixing ability w/ water • Petroleum or vegetable origin • 1-3 pints/ac, or 1% by volume • Better effect on postemergence app. compared to surfactants (both on weed and crop)

  33. Unit 2: Weed Control for Corn, SB, & Sorghum • Nonionic Surfactants (NIS) • Cause spreading & wetting action by decreasing surface tension of water • Mixes and spreads over waxy/hairy surfaces rather than form droplets • Increase herbicide absorption into the weed • .25 – 1 pint/ac., or 1/8 to ½ % volume • Should contain 75-85% active ingredient • Ammonium Fertilizers • Increase herbicide activity on weeds like velvetleaf • Usually ammonium sulfate or Urea-ammonium nitrate (28%)

  34. Unit 2: Weed Control for Corn, SB, & Sorghum • 28 – 2-4 quarts/ac. • Care should be used to reduce drift • Drift-reduction agents/retardants • Make sure you read the labels • Conservation Tillage & Weed Control • Minimum/ reduced till = any tillage system intentionally leaving crop residue on the soil surface • Mulch tillage = leave at least 30% of the soil covered w/ crop residue

  35. Unit 2: Weed Control for Corn, SB, & Sorghum • Ridge & Zero tillage = no major tillage prior to planting • Ridge till ideal for banding preemergence herbicides because cultivation is part of the plan • No-Till • Conserves soil moisture • Conserves soil • Saves fuel • Increase timeliness of planting

  36. Unit 2: Weed Control for Corn, SB, & Sorghum • If tillage eliminated before planting, must control existing weeds either before, at, or after planting • Greater reliance on chemical control of weeds • Preplant or postplant soil-applied not incorporated • Contact herbicides • Soil-residual herbicides may eliminate need for “knockdown” at planting • Early Preplant application may lead to more applications later in the season, or cultivation

  37. Unit 2: Weed Control for Corn, SB, & Sorghum • Today’s equipment much better suited for reduced-till systems • If done properly, crop residue should not effect herbicide distribution • Early preplant app. or postemergence herbicides often provide adequate control • Existing vegetation in corn and SB stubble is often annual weeds • If small, easily controlled w/ contact herbicide that has some soil-residual activity

  38. Unit 2: Weed Control for Corn, SB, & Sorghum • Broadleaves • 2,4-D or dicamba (Clarity) may be used prior to corn or no-till SB • Observe planting delay recommendations • Using Cover Crops • What are people in IL using? • What is the advantage of a cover crop? • Hairy vetch • Controlled w/ 2,4-D or dicamba before planting

  39. Unit 2: Weed Control for Corn, SB, & Sorghum • Winter rye or wheat • Controlled by glyphosate(ex. Touchdown) prior to planting corn or SB • How early should you spray? • Varies depending on the season • Dry – late control can dry out soil too much for the crop • Wet – late control can help to dry out the soil • Too much decomposing residue can inhibit the emergence/viability of the corn seedling

  40. Unit 2: Weed Control for Corn, SB, & Sorghum • Control of Perennial Sods • Pasture land or CRP returning to production • Perennial Grass Sods • Glyphosate is most effective • Fall application is best • Mow in late summer • Allow 6-8” growth before application • Springtime application • Must wait for 6-10” new growth • Paraquat + atrazine (Gramoxone Max) also very effective

  41. Unit 2: Weed Control for Corn, SB, & Sorghum • Perennial Legume Sods • Need 6-8” growth • Do not take a spring cutting (will delay corn planting too much) • When planting corn can follow with: • 2,4-D • Dicamba • Glyphosate • May apply glyphosate in the fall after the last cutting taken

  42. Unit 2: Weed Control for Corn, SB, & Sorghum • Fall Herbicide Applications • Increasing in popularity in IL • Two approaches: • First approach • Use soil-applied grass control herbicide to control annual grasses the following season • Usually in very northern IL • Helps to reduce workload in the spring • Disadvantage • Higher application rates

  43. Unit 2: Weed Control for Corn, SB, & Sorghum • Grass control may not last throughout following season • Second approach • Control winter annuals and perennials in no-till corn & SB • Used by those who have problems w/ control in the spring • Problem weeds • Marestail, chickweed, purple deadnettle • Form dense mat that makes burndown control difficult

  44. Unit 2: Weed Control for Corn, SB, & Sorghum • Insufficient spray coverage • Fluctuation in spring temperature • Timeliness of application • Potential benefits: • Prevent those mats that can interfere w/ planting and tillage • Reduce vegetation where insects may harbor • May allow earlier planting as soil may warm & dry sooner • Prevents these weeds from producing seed, reduces future weed problems

  45. Unit 2: Weed Control for Corn, SB, & Sorghum • Fall application of chemical takes the chemical w/ the food to roots, so you get complete root control as well • Can use higher application rates, if needed (some herbicides) • Three approaches to controlling winter annuals with fall herbicide app. • Apply a herbicide w/ residual soil activity before most winter annual weeds germinate • Use a nonresidual (glyphosate, 2,4-D, paraquat) to emerged while they are small • Combination of these two strategies

  46. Unit 2: Weed Control for Corn, SB, & Sorghum • Goal is to reduce the detrimental vegetation pressuring the crop at planting • Possibly eliminate need for spring burndown control • May or may not be effective • Herbicide selection • App. Rate • Weather • Time of planting

  47. Unit 2: Weed Control for Corn, SB, & Sorghum • How should you decide if this is a good tool for your operation? • If you’ve had a control problem in the past • Things to remember: • May not need fall application, if spring app. Provide satisfactory control • Spring burndown may still be needed even if you spray in the fall

More Related