Pasture Genetics_ Better Established Pastures and Forage Crops
Unit 3: Weed Control for Small Grains, Pasture, & Forage.
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Transcript of Unit 3: Weed Control for Small Grains, Pasture, & Forage.
Unit 3: Weed Control for Small Grains, Pasture, &
Forage
Unit 3: Weed Control for Small Grains, Pasture, & Forage Unit 3 Objectives:
Discuss the importance and options of chemical weed control
Identify the major areas of concern w/ each of these crops
Preplant vs. Postemergence herbicide options and the efficacy of each
Understanding of the harvest/feeding restrictions after application
Unit 3: Weed Control for Small Grains, Pasture, & Forage Introduction
If well established, these plants usually compete very well
Minimizes the need for chemical application Sometimes control is needed
Ex. Winter wheat and garlic Risk of dock if garlic population is too high
Small Grains Best control is done before the crop is
established in the fall Especially broadleaves
Tillage also aids in control of weeds
Unit 3: Weed Control for Small Grains, Pasture, & Forage
Proper seeding rate, optimal fertility, timely planting will also help
Crop is established faster Competes w/ weeds more effectively
Annual Grass problems Downy Brome & Cheat
Are significant competitors w/ wheat Few label clearances for control Tillage is best option Severe infestations may alter cropping decisions
Unit 3: Weed Control for Small Grains, Pasture, & Forage
Using Postemerge Herbicides for Broadleaf control
Nature of the weed problem ID and check infestation Size of the weed
Stage of the Crop Most herbicides are applied after full-tiller until boot
stage Don’t apply from boot to hard-dough stage
Herbicide Activity Determine crop tolerance and weed susceptibility May use broad spectrum tank mix for best control
Unit 3: Weed Control for Small Grains, Pasture, & Forage
Presence of a Legume Underseeding What are they referring to? Some formulations can cause significant damage
Economic Justification Do a cost/benefit comparison What factors must be considered?
Seedling Stage 1
Coleoptile emergence (sheath that surrounds the shoot)
All other leaves follow in this same succession
Unit 3: Weed Control for Small Grains, Pasture, & Forage
Tillering Stages 2-3
Shoots (tillers) emerge on opposite sides of plant from buds in the axils of first and second leaves
Next tillers arise from a shoot above the 1st and 2nd tillers or from tillers themselves
Results in several shoots Stages 4-5
Leaf sheath lengthens Appearance more like a stem True stems actually concealed w/in the leaf sheaths
Unit 3: Weed Control for Small Grains, Pasture, & Forage
Jointing Stage 6
Stem & leaf sheaths elongate rapidly First node becomes visible at the base of the shoot
Stage 7 Second node is visible Next to last leaf is emerging, but barely visible
Stage 8 Flag leaf visible, but still rolled
Stage 9 Preboot Ligule of the flag leaf is visible Head begins to enlarge w/in the sheath
Unit 3: Weed Control for Small Grains, Pasture, & Forage
Stage 10 Boot Sheath of flag leaf completely emerged Distended due to enlarging, but not yet visible head
Heading Stages 10.1 to 10.5
Heads of the main stem emerge first Stem continues to lengthen until head is raised several
inches above the upper leaf sheath
Flowering Stages 10.5.1 to 10.5.3
Flowering in order of head emergence Unpollinated flowers have no kernels
Unit 3: Weed Control for Small Grains, Pasture, & Forage
Stage 10.5.4 Premilk Flowering is complete Inner fluid is abundant and clear in developing kernels
Ripening Stage 11.1 Milk
Kernel fluid is milking white (starch) Stage 11.2 Dough
Kernel is soft yet beginning to dry (more starch accumulation)
Leaves and stems begin to yellow Stage 11.3
Kernel is hard and difficult to split w/ the thumbnail
Unit 3: Weed Control for Small Grains, Pasture, & Forage
Stage 11.4 Kernel is completely ripe Fragments when crushed Plant is dry and brittle
Annual Broadleaf Control Postemergence herbicides provide good control Aim, Banvel, Clarity, Buctril Must be applied during recommended stages of
growth to minimize crop damage Perennial Broadleaf Control
Difficult to control w/ the low recommended rates Higher rates can cause severe crop damage
Unit 3: Weed Control for Small Grains, Pasture, & Forage
Tillage in combination w/ herbicide before planting can provide better control
Banvel, Clarity Stinger
Also gets Canada Thistle Harmony GT
Control Wild Garlic Apply in spring (.3-.6 oz/ac)
Harmony Extra Chickweed, henbit, common lambsquarter, smartweed,
mustard Glyphosate
Can be applied before harvest After hard-dough, but >7d before harvest
Unit 3: Weed Control for Small Grains, Pasture, & Forage Grass Pastures
Broadleaves can cause extreme problems w/out control
Direct competition w/ forage grasses Negatively impacts nutrition potential and longevity
of pastures Some weeds poisonous
White Snakeroot Hemlock
Tremors, nervousness, coma, death, etc. All cattle, can be passed in milk Extreme to moderate toxicity
Unit 3: Weed Control for Small Grains, Pasture, & Forage
Mowing & grazing will help control annual weeds, but perennials continue to grow from rootstocks
Perennials cannot be controlled w/out a long term plan and can persist for many years
Mowing along w/ rotational grazing will provide fairly good control, and keep grass competitive
What are some herbicides that would provide good control of perennials? Rates? Restrictions?
Proper weed ID is critical Application timing also important
Unit 3: Weed Control for Small Grains, Pasture, & Forage
Treatments will vary from spring for annuals and biennials to summer during growth for perennials, even fall application may be best
Forage Legumes Weed pressure can reduce the vigor of legume
stands Reduce forage yield Reduce forage quality
Establishment Prepare a firm, weed-free seedbed Select an appropriate variety and follow nutrient
recommendations
Unit 3: Weed Control for Small Grains, Pasture, & Forage
If seeding w/ a companion crop: Seed companion crop at half rate for grain production Legume will have better chance to survive w/ less
stress If seeding w/out a companion crop:
Use appropriate herbicides for weed control
Preplant-Incorporated Herbicides Balan, Eptam, Treflan
Preplant incorporation for legumes not seeded w/ a companion crop
Control most annual grasses and some broadleaves Must be thoroughly incorporated to prevent loss Apply shortly before seeding to provide longest
control
Unit 3: Weed Control for Small Grains, Pasture, & Forage
If weed pressure doesn’t prohibit yield or quality:
Control w/ herbicide may not be necessary Simple mowing will help control Ex. Winter annuals don’t compete after first cutting
hay
Postemergence Herbicides Poast Plus, Select, Pursuit, Raptor Control for annuals and perennials Established Legumes
Best option is to maintain a dense, healthy stand
Unit 3: Weed Control for Small Grains, Pasture, & Forage
Chemical weed control often limited to late fall or early spring applications
Late fall application Apply after the last cutting taken Weeds are small and susceptible
Grass weeds are very hard to control in established alfalfa
Chickweed
Downy Brome
Cheat
Common Lambsquarters
Crabgrass
Fall Panicum
Foxtail
Poison Hemlock
Henbit
Johnsongrass
Pigweed
Quackgrass
Shattercane
Smartweed
White Snakeroot
Yellow Nutsedge
Unit 3: Weed Control for Small Grains, Pasture, & Forage Unit 3 Assignment
Identify 5 specific herbicides for control of annual and perennial weeds in both pasture and legume forage programs
Active ingredient Application rate Timing of application Withholding time for grazing, hay, or meat
Classify the weeds in this slideshow as annuals or perennials