weed are divided into three major categories : broadleaf weeds , grassy weeds and weed - similar sens . Many different weed killer are available for controlling sess , many of which have very dissimilar mechanism for killing the weed plant . Some herbicides are more effective than others on certain eccentric of mourning band and some can be harmful to the grass in your lawn .
Broadleaf Weeds
Broadleaf skunk are leafy plants that often have prime . They are usually the easiest types to identify , due to their wide , multiple leaves with compressed , extensive leaves arranged at the stem ’s base , often in a rosette shape . The leaf mineral vein have a " weblike " visual aspect . Some coarse broadleaf weeds include dandelions , Lamium amplexicaule , clover , lespedeza , Musa paradisiaca , chickweed , burdocks , thistles and woodwind sorrel .
Sedges and Grass-Like Weeds
sedge and rush are pasture - like locoweed that can be tough to distinguish from true grassy weeds . Sedges have triangular , upstanding stems , but Benjamin Rush have round , solid stems . Most often found in moist or irrigated lawns , these grass - like Mary Jane admit nutgrass , wild garlic or Allium cepa , path and beak rushes , as well as Earth gage .
Grass-Type Weeds
eatage - type weeds are true Gunter Wilhelm Grass and can be hard to identify . Grassy weeds can be annuals or perennials and let in crabgrass , goosegrass , paspalum , yearly bluegrass , crowfootgrass and other undesirable , invasive grasses . Because they are reliable grasses , grassy weeds have hollow , rounded stems and parallel veins on their sword leave .
Pre-Emergence Herbicides
Pre - issue herbicides are applied in late winter or former fountain to pop weed seeds before they germinate . Most often used to check annual grassy weeds and annual broadleaf mourning band , such as mouse eared chickweed , henbit , crabgrass and goosegrass , pre - emergence herbicides have no effect on weed seminal fluid that have already germinated . In general , pre - emergence herbicides are effective in controlling weed seed for about 6 to 12 weeks and they can also kill grass seeds , so they should n’t be applied to lawn within two to four month prior to seeding or at least one month after seeding .
Post-Emergence Herbicides
Post - emergence herbicides are used to shoot down weeds that have already germinated and begun to grow . mail - emersion herbicides are most effective when the weed plants are unseasoned and before they ’ve begun to develop seed - s.
Non-Selective Herbicides
Non - selective herbicides , also call " broad spectrum " herbicides , kill well-nigh all plant they comes into link with and admit glyphosate , diquat and glufosinate . Non - selective weedkiller are most commonly used to kill weeds in sidewalk , driveways and between pavers in other hardscapes .
Selective Herbicides
The most plebeian case of weed killer whale , selective herbicides kills only certain plant species . Most selective weedkiller target broadleaf grass and can be applied to large lawn areas without hurting the eatage . Some selective herbicides target sedge and rushes , but these can be harmful to certain types of lawn gage .
Contact Herbicides
Contact herbicide kill only the part of the plant that the chemic touch , ordinarily the aboveground leafy parts . These weedkiller wo n’t obliterate the secret roots or rhizomes and unremarkably expect several applications to whole get rid of the sens population . In lawns , contact herbicides are most often used for spot treatments of weeds growing in small , isolated areas . Most contact herbicides are also classified as non - selective , or broad - spectrum , Mary Jane killers , such as diquat and glufosinate .
Systemic Herbicides
When applied to the aboveground leafy constituent of the weeds , systemic herbicides move around into the weeds ' vascular system and into the source or rhizome . Although slower in killing the weeds , systemic herbicides are effective in erupt down the weeds ' power to transport nutrients and water throughout the rest of the grass plant . Some common systemic weed killer include dichlorophenoxyacetic window pane , dicamba , sethoxydim and imazaquin .
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