Cogongrass (Imperata cylindrica) is just one of the greatest invasive plant dangers in Alabama and also in the southeastern unified States. Although it has actually been right here for more than a century, the problem has considerably increased in the critical 20 years. Numerous land managers proactively and aggressively regulate cogongrass and Auburn university researchers have been functioning on remedies for cogongrass for plenty of years. This publication gives a an overview of many years of research and also is in the type of answers to the most typical questions concerning cogongrass management.

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Q: Can i hand pull cogongrass? 

Cogongrass has actually sharp leaf edges and also razor-sharp sprouts at ground level make hand pulling fairly hazardous. Furthermore, the is extremely difficult to traction cogongrass there is no leaving behind rhizomes (underground stems), make this technique largely ineffective, even for very tiny patches. 

Q: Will tillage alone regulate cogongrass? 

In areas that deserve to be accessed with machinery, repetitive tillage that breaks up the entire rhizome great will at some point exhaust the power reserves of cogongrass rhizomes. Tillage pieces the rhizome network, result in boost in brand-new shoot emergence. Once repeated after new shoot emergence, tillage will more disrupt growth and decrease stored energy reserves. This method of repetitive tillage deserve to work well over time. If tillage is no repeated, the cogongrass job may finish up thicker than it to be to start with. Likewise, shallow, infrequent tillage will usually not control cogongrass. Care must additionally be taken to clean tillage equipment to avoid spreading rhizomes. 

Q: Will prescribed fire regulate cogongrass? 

NO. Prescribed fire at any type of timing disclosure cogongrass to the hinderance of nearly all various other species. Cogongrass deserve to burn hot enough to kill fire tolerant species, also young loblolly and also longleaf pine. Burning dense patches that cogongrass when trees space at danger is no recommended. Cogongrass can additionally be spread by fire-plows that can drag rhizome piece to uninfested areas.

Q: Will grazing control cogongrass? 

Cogongrass was tested as a potential forage crop in Mississippi and also Florida an ext than 80 years earlier and was discovered to be essentially useless. Cattle will graze very young cogongrass shoots, however they often tend to protect against it as it matures. Cogongrass is high in silica and also low in forage quality. Some livestock producers have used mowing to stimulate new growth for livestock grazing, yet this is no an effective regulate strategy. 

Fig. 1. Cogongrass fires burn incredibly hot.
Fig. 2. Cogongrass rhizomes account for about 60 percent of tree biomass.
What is the finest herbicide to treat cogongrass?

Two herbicides, glyphosate and also imazapyr, are effective versus cogongrass. However, lock are usually situation specific and need multiple treatments for complete control. Glyphosate is the the safest option as soon as treating cogongrass about desirable trees, shrubs, or various other vegetation yet is typically less effective than imazapyr. Imazapyr is very effective but cannot it is in used close to most desirable vegetation, unless major injury or death of the vegetation can be tolerated. Some pines, including loblolly pine, space tolerant come imazapyr. Longleaf pine, however, is not tolerant that high rates of imazapyr.

Q: What price of this herbicides need to I use?

For any herbicide, usage rates need to be in accordance v label rates for the particular product you select. Because that glyphosate formulations that contain 41 percent energetic ingredient (4.0 lb./gal.), a 4 to 7 percent systems is recommended for spot treatments, and broadcast treatment rates should generally be in between 3 and also 5 quarts per acre. For glyphosate formulations the contain 54 percent energetic ingredient (5.4 lb./gal.), a 3.5 come 6 percent equipment is recommended for spot treatments, and broadcast treatment prices should usually be at 7 pt./acre. For imazapyr formulations that contain 22.6 percent active ingredient (2 lb./gal.), a 2 percent solution is recommended because that spot treatments, and broadcast treatment prices should typically be between 48 and 64 oz./acre. For imazapyr formulations that contain 43.3 percent energetic ingredient (4 lb./gal.), a 1 percent solution is recommended because that spot treatments, and also broadcast treatment rates should usually be in between 24 and also 32 oz./acre.

Q: Should ns tank mix glyphosate and imazapyr?

There is no antagonism in between glyphosate and also imazapyr, and also they can be tank mixed. There might be some benefit to mix the two herbicides if reduced imazapyr rates are used. However, at the high rates recommended here, research has not shown a strong benefit in mix the two herbicides. Tank mixing herbicides such together these with various modes of action may be beneficial to avoid herbicide resistance. Cogongrass, however, has not been found to it is in resistant to either glyphosate or imazapyr in any case.

Q: What is the finest herbicide applications timing?

A single application of either glyphosate or imazapyr will rarely, if ever, totally eliminate the whole rhizome great at any kind of timing. However, the optimal treatment home window for both herbicides is late summer through at an early stage fall. If spraying in the fall, that is necessary to spray beforehand enough to offer the therapy time to occupational (approximately 4 weeks) before a death frost. 

Q: Can ns treat in the at an early stage spring to protect against cogongrass flowering and also seed production?

Early spring treatment of the an initial green cogongrass shoots usually provides inconsistent palliation of flowering. However, loss treatment has actually worked an extremely well to protect against flowering the complying with spring.

Q: Should I include surfactant to the tank?

For glyphosate, part products already contain a integrated surfactant and do no need any extra. If the brand recommends it, include a nonionic surfactant in ~ 0.25 to 0.5 percent v/v. If water hardness is an issue, the addition of ammonium sulfate come the spray tank is recommended once using glyphosate. Because that imazapyr, add a nonionic surfactant at 0.25 percent v/v or methylated seed oil at 1 percent v/v relying on the herbicide formulation used.

Q: Should I add a dye or spray indicator?

A blue spray indicator is beneficial when clues spraying small cogongrass patches and is generally easier to view on the cure foliage 보다 are various other colors, such together red. Spray indications are not usually necessary for broadcast applications. Spray indications are easy to job-related with and do no stain the way some true dyes stain.

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Q: Should i mow or burn to eliminate the thatch layer before treatment?

For summer or fall treatments, the answer is no. For spring treatments, remove the old growth may stimulate brand-new cogongrass expansion and result in more leaf area at the moment of treatment. However, as previously discussed, burning cogongrass at any time may injure or kill numerous trees. Over there is additionally some proof that mowing or burning in the winter may stimulate flower in the spring. 

Q: How lot regrowth carry out I require if I arrangement to spray after ~ mowing or burning?

It is usually great to allow at the very least 12 come 18 inch of regrowth prior to treating. If you treat with less regrowth, regulate may it is in poor. That is likewise fine to allow more than 18 inches of regrowth. 

Q: Should ns spray past the sheet of the patch?

Cogongrass spreads laterally by rise rhizomes. You have the right to often discover a couple of small shoots creeping out past the patch sheet into plenty of vegetation types. Part applicators have actually reported the formation of cogongrass halos approximately patches in the farming season after treatment. This has prompted some applicators come spray a band around 10 feet broad beyond the patch edge. This is not recommended if you are using glyphosate, because it has no floor activity. This is a useful option if you are using imazapyr, since it may administer several month of soil activity. Quickly digging out past the patch sheet will aid you identify the pervasiveness of rhizomes beyond the job edge.