Unit 9: Basic Weed Scouting. Unit 9 Objectives: – Knowledge of basic scouting procedures – Understanding of proper scouting times – Using field weed surveys

Unit 9: Basic Weed Scouting


Unit 9 Objectives:– Knowledge of basic scouting procedures– Understanding of proper scouting times – Using field weed surveys– Basic weed ID


Early season weed scouting– Done within 2 wks of planting after emergence

Also can determine:– Need for hoeing– Preemergence & preplant herbicides– Need for post emergence herbicides

– ID and record weed species


– Determine severity of weed infestation Count number of weeds/10’ of row for heavy

infestations, weeds/100’ of row for light infestations Sample area <5 ac Record weed height & growth stage

– Also note soil conditions Can help indicate herbicide effectiveness

– Too dry, not enough moisture for chemical uptake– Too wet, herbicide may have leached through root zone


– Identify weeds as early as possible for most effective control

Weed mapping– Complete a detailed weed map of each field by

mid-May– Will help you monitor changes in weed population

throughout the year, & from year to year– Include:

Perennial weed locations


Annual weed locations & infestation levels Mark distinguishing features

Final weed survey– Timing: late July to mid-August– Add to, or complete another weed map– Don’t generalize observations from areas near

waterways, poorly drained areas, next to borders– Rank species from most commonly to least

commonly found


Economic Threshold guidelines– Weeds and crop compete for the same resources:

Soil Fertility Sunlight Water

– Problems other than yield losses: Clogging, damaging harvest equipment Loss of cash rented ground to “neater” farmers


– Weed infestations the first 4-6 wks, then treatment = no economic losses

– No weeds first 4-6 wks, then weed infestation = minimal yield losses, but increased weed seed production

– Similar weeds typically cause economic losses in similar crops

Grass weeds to grass type crops Corn weeds to corn type crops Broadleaf weeds to broadleaf type crops (soybeans)


Giant Foxtail– Blade is densely hairy– Ligule has fringe hairs– Found through the Midwest

Giant Foxtail


Yellow foxtail– Sheath is flattened, smooth with split,

overlapping, smooth margins– Blade is smooth with long hairs– Ligule has fringe hairs

Yellow Foxtail


Green Foxtail– Sheath – round to slightly flat w/ split, overlapping

hairy margins– Blade is smooth to rough w/ rough margins– Ligule is a fringe of hairs– Continuous hairy collar

Green Foxtail


Fall Panicum– Sheath – slightly flat, smooth w/ split, overlapping

membranous margins– Blade is smooth w/ prominent mid-vein– Ligule is a fringe of hairs– Continuous collar

Fall Panicum


Shattercane– Sheath – rounded and smooth w/ split,

overlapping thin, membranous margin– Blade – flat w/ sparsely placed hairs on upper

surface– Ligule – long, membranous, rounded w/ jagged

ciliated margin

Shattercane


Johnsongrass– Very similar to shattercane

Johnsongrass


Yellow Nutsedge– Leaves – triangular, taper to a point, greenish

yellow– Very distinctive

Yellow Nutsedge


Quackgrass– Sheath – rounded w/ sparse, short hairs, can be

smooth & split, overlapping margins– Blade – flat, rough to smooth– Ligule – short, membranous, truncate in shape

Quackgrass


Burcucumber– Hypcotyl – green & rough– Cotyledons – oblong to spoon shaped– True leaves – alternate, pentagon shaped

somewhat hairy– Petioles – long & greed– Fruit – barbed, prickly bristles

Burcucumber


Common Cocklebur– Hypcotyl – smooth, fleshy, purple tinge near soil– Cotyledons – fleshy, shiny, long and thin shaped– True leaves – opposite (first pair), alternate later

Serrated leaves Oval in shape Rough to hairy surface

– Petioles – long, hairy, can be purple spotted

Common Cocklebur


Jimsonweed– Hypcotyl – fleshy, purple tinged, smooth– Cotyledons – smooth, narrow, short petioles– True leaves – alternate, large, smooth, pointed

apex, toothed margins– Petioles – long, pale green to purple, may have

short hairs

Jimsonweed


Common Lambquarters– Hypcotyl – purple, smooth– Cotyledons – fleshy, long, oval, dull color– True leaves – seem paired at first, become

alternate Pale green Oval shape Irregular toothed margins

– Petioles – long, pale green

Common Lambsquarters


Ivyleaf Morningglory– Hypcotyl – dull green to purple, crease along both

sides– Cotyledons – shiny, smooth, deeply indented

base– True leaves – alternate, hairy, three lobed leaves– Petioles – long, hairy, green to reddish tint

Ivyleaf Morningglory


Pitted Morningglory– Hypcotyl – smooth, somewhat purple– Cotyledons – smooth, butterfly shaped, deeply

indented lobes, pointed– True leaves – alternate, smooth, heart shaped,

maybe purple margins– Petioles – long and pale green to purple

Pitted Morningglory


Tall Morningglory– Hypcotyl – dull green to purple, smooth– Cotyledons – shiny, smooth, deeply indented

base– True leaves – alternate, hairy broadly heart

shaped, pointed apex– Petioles – long, hairy, dull green to reddish tint

Tall Morningglory


Eastern Black Nightshade– Hypcotyl – reddish to purple– Cotyledons – pointed tip w/ sparse hairs– True leaves – alternate, oval, wavy tooth margins

Underside – red to purple

– Petioles – red, purple, green, sparse hairs

Eastern Black Nightshade


Smooth Pigweed– Hypcotyl – reddish purple– Cotyledons – oblong, purple tinge, rough to

smooth– True leaves – alternate, oval, notched or pointed

apex, pale green to reddish– Petioles – long, may be hairy– Root – long, red taproot

Smooth Pigweed


Common Ragweed– Hypcotyl – purplish, rigid, rough– Cotyledons – club-shaped, rounded apex, smooth

surface– True leaves – opposite, irregular lobed– Petioles – grooved, widen to V-shaped stem

Common Ragweed


Giant Ragweed– Hypcotyl – smooth, shiny, can be purple blotched– Cotyledons – spatulate, rounded apex gradually

narrowing to base, smooth, shiny– True leaves – opposite, oval, pointed w/ serrated

margins, rough short-haired surface– Petioles – concave above, winged toward stem,

rough hairy surface

Giant Ragweed


Smartweed– Hypcotyl – smooth, tinged dark purple– Cotyledons – smooth, fleshy, elongated, shiny w/

hairy margins– True leaves – alternate and elongated, shiny, may

be spotted purple, hairy margins– Petioles – short, arise from swollen joints

Smartweed


Waterhemp– Hypcotyl – reddish purple– Cotyledons – oblong, purple tinge– True leaves – alternate, narrow oval to elongated,

pale greed to reddish, smooth– Petioles - long

Waterhemp


Velvetleaf– Hypcotyl – velvety, soft short hairs– Cotyledons – heart shaped, rounded apex, fuzzy

surface– True leaves – alternate, heart shaped, rounded

apex, serrated margin, velvety surface– Petioles – round, covered w/ soft hairs

Velvetleaf


Field Bindweed (perennial)– Hypcotyl – smooth– Cotyledons – kidney shaped– True leaves – alternate, spade shaped, smooth– Petioles - smooth

Field Bindweed


Hedge Bindweed (perennial)– Hypcotyl – smooth– Cotyledons – kidney shaped– True leaves – alternate, larger than field

bindweed, arrowhead shaped– Petioles - smooth

Hedge Bindweed


Hemp Dogbane (perennial)– Hypcotyl – red above ground– Cotyledons – elongated, smooth– True leaves – opposite, elliptic, thick, shiny, white

midvein– Petioles – short, smooth, “milklike” sap

Hemp Dogbane


Common Milkweed (perennial)– Hypcotyl – pale green to purple– Cotyledons – elliptical, thick, covered w/ short

hairs– True leaves – opposite, thick, dull, velvety,

elliptical, pointed– Petioles – ridged, “milklike” sap

Common Milkweed


Honeyvine Milkweed (perennial)– Hypcotyl – green to slightly pink, smooth– Cotyledons – shiny, oblong, rounded apex,

narrows into long petiole– True leaves – opposite, oblong to heart shaped,

pointed apex, dull green to bluish tint– Petioles – long, sparsely hair covered

Honeyvine Milkweed

Documents

Unit 9: Basic Weed Scouting. Unit 9 Objectives: – Knowledge of basic scouting procedures – Understanding of proper scouting times – Using field weed surveys