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Smooth and Downy Brome Identification and Control

April 25, 2014

In the early spring before Kentucky bluegrass breaks dormancy and after Kentucky bluegrass shut down for the season in the fall, smooth brome stands out as a course textured patch in your lawn, sod farm, golf course rough, or sports field. During the growing season, its color and texture are comparable to Kentucky bluegrass and is not as much of a nuisance.  

Both brome species (Smooth and Downy) can act as weeds in high quality turf areas. Smooth brome has many desirable characteristics to function as a useful turfgrass species; however, its poor density limits the use to low-maintenance areas. 

There are several identification traits distinguishing brome grass from many other weeds. The sheath is nearly closed, giving it a V-neck sweater appearance. Brome has a rolled vernation, hairy sheaths and blades as well as a distinctive “watermark” (or W-shaped) on its leaves as seen below in Photo 1.  Its spindly-natured leaves, small membranous ligule, and winter annual growth habit can usually identify Downy brome. Brome spreads rapidly by its extension rhizome system and its seeds are often carried by wind/birds from low maintenance areas to well-maintained turf. 

 

There is no guaranteed selective control for Smooth brome in Kentucky bluegrass, creeping bentgrass, or perennial ryegrass turf. Early research from Zac Reicher and Matt Sousek at the University of Nebraska has shown earlier year application (June) rather than (July) will aid in Tenacity control of smooth brome in Kentucky bluegrass. This study will be replicated in 2014 and further data will be passed along as available. Downy brome can be controlled with the preemergence herbicide Siduron and post-emergent Sethoxydim (only for use in established fine fescue stands; tall fescue slightly tolerant).

In most cases, a nonselective, systemic herbicide should be used and multiple applications may be needed to effectively control brome grass. 

Photo 1: Smooth bromegrass’s v-neck sheath and “w-shaped” watermark at midway point of leaf blade. Photo courtesy of Stephen K. Barnhart, Iowa State Press (1997). 

Photo 2. Picture of Downy brome taken this week at the ISU research station. You can see the v-neck sheath as well as fine hairs.

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WILL TENACITY (MESOTRIONE) KILL QUACKGRASS?

May 27, 2014

Quackgrass (Elymus repens) is the hardest turf weed to control that I know of.  You can identify it by the long clasping auricles on its collar (Fig. 1) and by its extensive rhizome system (Fig. 2).  I get the question occasionally whether the new herbicide Tenacity (mesotrione) will selectively control this species.  The answer is “no”.

Figure 1. Auricles

 Figure 2.  Rhizomes

We just treated the Kentucky bluegrass (Poa pratensis) turf at the research station shown in Figure 3.  The result is that the quackgrass turns white, as can be seen in the picture.  That always gets peoples hopes up, including mine when I first started working with this product.  Unfortunately, the quackgrass always recovers and comes back as bad as ever.  Repeat applications do not work either.  I tried for 4 seasons to kill patches in my own lawn, hoping that my tenacious applications of Tenacity would kill it.  I lost, and the quackgrass was not even reduced in severity by my repeated applications.

Figure 3. Quackgrass turned white by Tenacity.

The only way to control it remains non-selective applications of Roundup (glyphosate).  The rhizomes are very hard to kill and repeated applications of Roundup will be necessary.  If you have this problem and want to get rid of the quackgrass, start now in May by killing the infested areas.  Then repeat apply every time the quackgrass comes back from rhizomes.  You should set a goal of reseeding in mid-August.  

Even a better solution would be to sod over the dead areas.  The rhizomes have a harder time emerging through sod than they do into a newly seeded area.

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