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


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


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


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


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


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


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


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


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


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


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


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


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


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

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

Unit 3: Weed Control for Small Grains, Pasture, & Forage.

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