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 1 st and 2 nd 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 to  Flowering in order of head emergence  Unpollinated flowers have no kernels

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