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Imazapyr 4 SL Herbicide

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Imazapyr 4 SL Herbicide is a pre-emergent and post-emergent bare ground herbicide for control of unwanted vegetation in non-cropland areas and aquatic sites. It will sterilize the soil it is sprayed over and nothing will grow for up to 1 year. Imazapyr Can also be used in pastures, rangelands and other listed areas.

Target Pests

Imazapyr 4 SL Herbicide can control grasses such as bluegrass bahiagrass barnyardgrass bermudagrass cattail crabgrass dallisgrass fescue goosegrass itchgrass johnsongrass lovegrass kentucky bluegrass saltgrass sandbur wild barley wild oats witchgrass and other listed grasses.

Imazapyr 4 SL Herbicide can control broadleaf weeds such as bull thistle burclover carpetweed chickweed clover ragweed dandelion dock fiddleneck goldenrod henbit horseweed kochia milkweed pigweed primrose smartweed sorrell sowthistle spurge sunflower wild carrot wild lettuce yellow woodsorrell and other listed weeds.

Imazapyr 4 SL Herbicide can also control vines and brambles woody brush and certain trees as well as aquatic weeds.

For Use In

Imazapyr 4 SL Herbicide is for use in non-croplands such as utility pipeline railroad utility plant sites highway rights-of-way petroleum tank farms fence rows storage areas pumping installations non-irrigation ditchbanks under paved surfaces rangeland and grass pastures.


For a broadcast low volume foliar application mix at a rate of 1 1/3-6 2/3 ounce Imazapyr plus 1/3 ounce of non-ionic surfactant per gallon of water. Imazapyr 4 SL Herbicide should be used at a rate of 1-3 pints per acre for control of grassy and broadleaf weeds.

For aquatic treatment use Imazapyr 4 SL Herbicide at a rate of 0.5-1.5 pints per acre. Not to exceed 1.5 pints per acre per year.

Coverage Area

Coverage area of Imazapyr 4 SL Herbicide varies depending on application but not to exceed 3 pints per acre per year.

Time to Kill

Imazapyr 4 SL Herbicide begins to eliminate unwanted weeds within turf just after application but can take up to several weeks to completely kill of the target weeds.

Mix Rate

Mix at a rate of 1 1/3-6 2/3 ounce Imazapyr plus 1/3 ounce of non-ionic surfactant per gallon of water.

Active Ingredient

Isopropylamine salt of Imazapyr 52.6%

Imazapyr 4 SL Herbicide

Imazapyr 4 SL Herbicide

Imazapyr 4 SL, with Imazapyr 52.6% is a broad-spectrum, pre and post-emergent spray for control of most broadleaf weeds, vines, brambles, annual and perennial grasses, trees for forestry site preparation, hardwood brush, and release of conifers from woody and herbaceous competition. It is used for bare ground control of unwanted vegetation, sterilizing the soil it is sprayed over for up to a year. Compare Imazapyr 4 SL to Arsenal AC

Why Imazapyr Is So Effective

Vegetation absorbs Imazapyr through the roots and foliage. It moves throughout the plant causing chlorosis (a yellowing of plant tissues). Afterward, tissue necrosis is spread throughout. After application, Alligare Imazapyr 4 SL moves to the roots of the plant and kills the roots and underground storage tissue and prevents most emerging growth. The tissue necrosis and chlorosis may appear for several weeks in some plant species. It may take months for woody plants, brush, and trees to show the necrosis or chlorosis.

Product Q & A

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What is the difference between Imazapyr 2sl and Imazapyr 4sl?
Eddy on Nov 3, 2016
BEST ANSWER: Difference between Imazapyr 2sl and Imazapyr 4sl is that the 2SL stands for 2lbs of active ingredients vs the 4SL, which is 4 lb's active ingredients.
If imazapyr 4 sl is double the strength of 2sl why are the mixing rate tables the same on the label ?
A shopper on Jul 24, 2018
BEST ANSWER: The application will vary depending on the targeted weed and the area of application. They will look similar but you will use less of the 4sl compared to the 2sl.
Is it harmful to wild life? Or dogs?
A shopper on Aug 8, 2018
BEST ANSWER: The product is hazardous to domesticated animals. Please exercise caution and apply according to label directions.
Will this kill Japanese Knotweed?
Thomas S on Jul 20, 2018
BEST ANSWER: Alligare Imazapyr 4 SL provides postemergence control and some residual control of the following
target weed species. The degree of control is both species and rate dependent. Use
Alligare Imazapyr 4 SL only in accordance with the directions on this label.

Yes, it does list Japanese Knotweed on the label as a weed controlled.
will this kill Matgrass
butch on Jun 4, 2017
BEST ANSWER: Matgrass is not listed as a controlled weed on the Imazapyr label, you can spot treat with Glyphodsate.

Impacts: Matgrass is an uncommon non-native grass with the potential to
out-compete desirable grasses and forbs Because it is a species of low
palatability it is not favored by grazing livestock or wildlife giving matgrass
a competitive edge. Impacts to coastal habitats are less well known, but
early surveys reveal an aggressive invader that pushes out native
flora. One of the challenges in controlling matgrass is identifying it amongst
other native or desirable forage species. Untreated plants develop seeds
and perpetuate infestations for decades
If used as a spot treatment, is it as likely to affect trees nearby thru root transmission? We have limited amounts of Japanese knotweed on a berm area we'd like to sod. There are larger plants on the back of the berm which will require more intense treatment.
Jan K on Aug 12, 2018
BEST ANSWER: Careful spot treatment should minimize the chances that nearby trees are affected. Please check the label for more details on preventing desired trees and plants from being damaged.
Will Imazapyr kill phragmites?
A shopper on Jul 20, 2018
BEST ANSWER: The species of annual and perennial grasses controlled by Alligare Imazapyr 4 SL include
the following:
Annual bluegrass (Poa annua)
Bahiagrass (Paspalum notatum)
Barnyardgrass (Echinochloa crus-galli)
Beardgrass (Andropogon spp.)
Bermudagrass (Cynodon dactylon)
Big bluestem (Andropogon gerardii)
Broadleaf signalgrass (Brachiaria platyphylla)
Canada bluegrass (Poa compressa)
Cattail (Typha spp.)
Cheat (Bromus secalinus)
Cogongrass (Imperata cylindrica)
Crabgrass (Digitaria spp.)
Crowfootgrass (Dactyloctenium aegyptium)
Dallisgrass (Paspalum dilatatum)
Downy brome (Bromus tectorum)
Fall panicum (Panicum dichotomiflorum)
Feathertop (Pennisetum villosum)
Fescue (Festuca spp.)
Foxtail (Setaria spp.)
Giant reed (Arundo donax)
Goosegrass (Eleusine indica)
Guineagrass (Panicum maximum)
Italian ryegrass (Lolium multiflorum)
Itchgrass (Rottboellia exaltata)
Johnsongrass (Sorghum halepense)
Junglerice (Echinochloa colonum)
Kentucky bluegrass (Poa pratensis)
Lovegrass (Eragrostis spp.)
Orchardgrass (Dactylis glomerata)
Panicum spp.
Paragrass (Brachiaria mutica)
Phragmites (Phragmites australis)
Prairie cordgrass (Spartina pectinata)
Prairie threeawn (Aristida oligantha)
Quackgrass (Agropyron repens)
Reed canarygrass (Phalaris arundinacea)
Will this kill tomatoes?
Nicole R on Jul 20, 2018
BEST ANSWER: Yes, Imazapyr 4 SL will kill tomato plants.
What is the recommended mixing ratio for small tank sprayer (16 gal) when this is used for bare ground applications?
Ampped on Jan 7, 2018
This product is an effective herbicide for preemergence or postemergence control of many annual
and perennial broadleaf and grass weeds where bare ground is desired. This product is
particularly effective on hard-to-control perennial grasses. This product at 0.75 to 3 pints per acre
can be used alone or in tank mix with Diuron, Simazine, Vanquish®, or other registered herbicides
labeled for this use. The degree and duration of control are dependent on the rate of this product
used, tank-mix partner, the volume of carrier, soil texture, rainfall and other conditions.

About 1.11 ounce at the high rate per 1,000 square feet, you would want to apply with 2 gallons of water.

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