Fescue Control Trial

There are over a dozen invasive plant species that are on the priority list for control at Blue Jay Barrens.  For some, I’ve found effective control techniques and those species are slowly being removed from the landscape.  For others, I’m still trying to discover effective control techniques.  One group that I am currently working on is made up of introduced cool season grasses commonly used for pasture, hay or landscape purposes.  The most visible members of that group are Tall Fescue, Orchard Grass, Timothy and Kentucky Bluegrass.  They all begin growth early in the season, slow down or enter dormancy during the heat of summer and revive to grow into late fall.  They are most easily detected in late spring when they overtop slower growing vegetation and send up their flower stalks.

Varieties of all of these grasses have been developed to be super vigorous and highly competitive.  Many native plants cannot survive the competition and disappear.  The challenge is to find a way to remove the invasive grasses from the stand without harming the natives.  I have some ideas and decided to try one out on the grass along the trails.  This is what a typical untreated trail edge looks like.  A secondary reason for conducting my trials along the trail edges was the fact that the mature fescue seed stalks lean out into the trail at the precise time that chigger activity peaks.  Brushing the stalks while walking invariably results in chigger bites, so no grass also means fewer chigger bites.

This point, formed by a fork in the trails, was last year thick with Tall Fescue.  Tall Fescue is the most aggressive of the four grasses mentioned.  Having been used for years for pasture, hay and erosion control, Tall Fescue is present on probably every farm in southern Ohio.  Kentucky 31 Tall Fescue was considered the farmer’s friend and because of its ability to survive on the poorest of soils, is probably responsible for much of the farmland soil remaining on the hillsides.  It’s a tough grass, but it has been eliminated from this small spot and the natives remain.

Last December 2, I used the brush mower to trim down dead stalks along the trail and expose the still green fescue beneath. I then applied a 2% solution of glyphosate to the cut grass.  Since most of the native species were dormant with top growth dead, there was no danger of their being damaged by the herbicide.

The effect of the herbicide is clear to see.  In the treated area the non-native grasses have been eliminated.  The untreated area farther from the trail still has a thick stand of grass.

In a very few areas, the treatment was not successful.  Even though the forecast was for dry conditions throughout the day of treatment, a rain shower hit the area about three hours after the herbicide application.  The spray should have had time to dry and adhere to the grass leaves, but since it was cool and I had just mowed off a large part of the leaf, it’s possible that the chemical was diluted enough to render it ineffective.  It could also be that a clump of cut vegetation covered this patch of grass and intercepted the spray or, even though highly unlikely, the guy wielding the backpack sprayer may have just missed this spot.

I noticed just one native species that did not survive the herbicide treatment.  Golden Ragwort, notorious for maintaining green leaves through the winter, went the way of the exotic grasses.  In this case it was just an area about three feet long that contained the ragworts, but it does illustrate a potential problem with this treatment method.  Any green plant still actively growing will fall victim to the glyphosate.  Before using this method of grass control it is essential that you know what other plants might be susceptible to the spray.  Then a decision can be made as to whether those plants should be sacrificed in order to remove the grass.  In this case, Golden Ragworts are quite common here and will quickly move back into their former haunt.

Other species are taking full advantage of their life without competition.  These Wingstem plants are out to set an all time height record.

The area along this trail used to contain a great stand of Monarda fistulosa.  The Monarda suddenly disappeared a few years ago.  It’s been slowly recovering and shows no damage from the glyphosate treatment.  I’m hoping that a few more years will find it back in its glory.

I’ve tried the December applied glyphosate treatment in the past on small, nine or twelve square foot plots.  One potential problem is leaving bare ground into which invasive plants can get a foothold. This is especially true with extremely thick stands of grass.  If native species cover less than half of the treated area, there is a high likelihood that colonizing weed species will appear on the site.  Teasel, Johnson Grass and Canada Thistle are some that are problems in this area.  Native annuals, such as the Giant Ragweed shown here, also take advantage of the exposed ground.  Giant Ragweed has always been a part of the flora along this section of trail and doesn’t cause me much concern.  It may be a bit more prevalent for a couple of years, but will soon return to its normal scattering of plants.

The native prairie grasses suffer no damage.  Their top growth has already died back by the time the glyphosate is sprayed.

This section of trail shows a healthy Indian Grass border.  The grass will be leaning in and just about closing the trail by September, but it doesn’t bother me as long as it’s native.

The next step in controlling the invasive grasses will be to move away from the trail and into the field.  I’ll monitor the area along the trail through the summer and if things seem to go well, I’ll treat some larger sections of the field this winter.