Control-Suppression of Bermuda Grass in Tall Fescue - Ask Extension
For sure this is a difficult problem. I have been using a very low concentration of Fusilade II (less than 50% label) in late summer to suppress the B...
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Control-Suppression of Bermuda Grass in Tall Fescue #855059
Asked November 10, 2023, 10:52 AM EST
For sure this is a difficult problem. I have been using a very low concentration of Fusilade II (less than 50% label) in late summer to suppress the Bermuda grass in Fescue lawn, then 2-3 weeks later as the Bermuda grass is "bleaching", I'll then mechanically remove what appears to be unhealthy Bermuda grass from my Fescue lawn using a tow behind dethatcher. And it picks up a lot of the bermuda grass, usually 2-3 55 gallon drums in volume. I burn it. (out of spite LOL) The dethatcher is pretty rough on the fescue, and I'll aerate and re-seed Fescue in those areas... and by mid-November all looks great. But it seems to be a losing battle, and every mid-summer the Bermuda grass returns and seems even stronger. Would it be helpful to use a light concentration Fusilade in early spring? I don't want to damage the Fescue in spring. Any other ideas? I looked at Pylex bu tit is really really costly. I wish my Fescue lawn would look like to does now, mid-November: all year long.....Thanks.
Calvert County Maryland
Expert Response
We looked-up a Fusilade II label to check its requirements and recommendations, though the label physically attached to your product's bottle takes precedence in case there are several different versions or formulations of it. On the label we consulted, the manufacturer states: "not for use on home lawns" under the Weed Control in Desirable Turfgrasses section. The General Precautions section above it states: "For use only by commercial or licensed applicators when applications are to be made in or around homes." The Maryland Department of Agriculture, which regulates pesticides and which certifies pesticide applicators, does not appear to list Fusilade II as restricted-use, so you might need to clarify with them if this product can be used by the general public in Maryland. (We sent our own message to ask, but might not hear back for a few days.) Generally, the product label information is the primary reference as it must be EPA-approved and therefore carries federal legal weight.
Aside from that potential issue, the use of Fusilade II for Bermudagrass treatment will require the proper dosage (the full label rate, not more dilute unless the label specifically suggests it to spare the fescue from damage) plus the addition of a surfactant, as instructed by the label directions we consulted. Surfactants aid pesticide function by (in this case) improving how easily the spray is absorbed by the foliage and can also resist dilution by rain or irrigation. They are added to the pesticide solution just before application and the usage instructions for the surfactant will be included on its own label, though guidance for dilution is also included in the Fusilade II label. Surfactants are sold alongside pesticides at garden centers.
We understand your catharsis from burning the weeds, but never burn any plants treated with a pesticide (herbicides included), or you may be volatilizing its active or inert ingredients, risking inhalation exposure and environmental contamination.
The active ingredient glyphosate might be more effective than the ingredient in Fusilade II, which is fluazifop. Granted, any turfgrass contact with glyphosate can result in dieback, but since surviving Bermudagrass may eventually out-compete the fescue anyway, this amount of collateral damage is probably not that great a detriment. If there do happen to be usage restrictions for Fusilade II in Maryland by non-certified applicators, then a glyphosate-containing product might be the most practical alternative.
It would be much simpler and likely cheaper over the long term to just strip Bermudagrass-infested areas of sod and reseed or re-sod them. Using Maryland Certified Sod will essentially give you a weed-free start to the lawn for at least a couple years. The ideal time of year to establish fescue from seed or sod is late summer into early autumn, though there is a more limited window of opportunity in spring. Living fragments of Bermudagrass stolons not removed by the sod stripping might infiltrate the new turf, but either you could let them resprout after sod removal first to treat them with glyphosate, or spot-treat them once the sod is established.
A Virginia Tech publication on Selective Bermudagrass Control for Lawns points-out that cultural control methods (physically changing growing conditions for the weed or which improve turfgrass vigor) are necessary to aid in the efficacy of any chemical control. Mowing lawns high, which helps the turf shade the Bermudagrass, could drastically reduce the amount of herbicide needed and the frequency of re-applying it. Pylex is included in its assessment of chemical suppression options; note that it too requires the addition of an adjuvant. (Adjuvant is another term for these additives that aid in pesticide function, and surfactants are one type of adjuvant.)
In summary, the worst-case scenario is that you will continue to battle Bermudagrass in the fescue in perpetuity, or that a complete overhaul to redo the lawn would be needed to finally get rid of the infestation. Areas you don't need to maintain as lawn for the sake of foot traffic tolerance or any HOA regulations could be gradually converted to alternative plantings, which may be easier to keep weed-free and which should not need as much upkeep as long as the plants chosen suit the site conditions.
Miri
Aside from that potential issue, the use of Fusilade II for Bermudagrass treatment will require the proper dosage (the full label rate, not more dilute unless the label specifically suggests it to spare the fescue from damage) plus the addition of a surfactant, as instructed by the label directions we consulted. Surfactants aid pesticide function by (in this case) improving how easily the spray is absorbed by the foliage and can also resist dilution by rain or irrigation. They are added to the pesticide solution just before application and the usage instructions for the surfactant will be included on its own label, though guidance for dilution is also included in the Fusilade II label. Surfactants are sold alongside pesticides at garden centers.
We understand your catharsis from burning the weeds, but never burn any plants treated with a pesticide (herbicides included), or you may be volatilizing its active or inert ingredients, risking inhalation exposure and environmental contamination.
The active ingredient glyphosate might be more effective than the ingredient in Fusilade II, which is fluazifop. Granted, any turfgrass contact with glyphosate can result in dieback, but since surviving Bermudagrass may eventually out-compete the fescue anyway, this amount of collateral damage is probably not that great a detriment. If there do happen to be usage restrictions for Fusilade II in Maryland by non-certified applicators, then a glyphosate-containing product might be the most practical alternative.
It would be much simpler and likely cheaper over the long term to just strip Bermudagrass-infested areas of sod and reseed or re-sod them. Using Maryland Certified Sod will essentially give you a weed-free start to the lawn for at least a couple years. The ideal time of year to establish fescue from seed or sod is late summer into early autumn, though there is a more limited window of opportunity in spring. Living fragments of Bermudagrass stolons not removed by the sod stripping might infiltrate the new turf, but either you could let them resprout after sod removal first to treat them with glyphosate, or spot-treat them once the sod is established.
A Virginia Tech publication on Selective Bermudagrass Control for Lawns points-out that cultural control methods (physically changing growing conditions for the weed or which improve turfgrass vigor) are necessary to aid in the efficacy of any chemical control. Mowing lawns high, which helps the turf shade the Bermudagrass, could drastically reduce the amount of herbicide needed and the frequency of re-applying it. Pylex is included in its assessment of chemical suppression options; note that it too requires the addition of an adjuvant. (Adjuvant is another term for these additives that aid in pesticide function, and surfactants are one type of adjuvant.)
In summary, the worst-case scenario is that you will continue to battle Bermudagrass in the fescue in perpetuity, or that a complete overhaul to redo the lawn would be needed to finally get rid of the infestation. Areas you don't need to maintain as lawn for the sake of foot traffic tolerance or any HOA regulations could be gradually converted to alternative plantings, which may be easier to keep weed-free and which should not need as much upkeep as long as the plants chosen suit the site conditions.
Miri
