# Controlling Grassy Weeds in Perennial Rye



## Movingshrub (Jun 12, 2017)

This is my first thread in the cool season side of the forum.

I have a mixed warm season lawn that I'm looking to renovate in 2019, which will be replaced with bermudagrass.

I intend to kill off the lawn this summer/fall and then seed with perennial rye to serve as a lawn from late September 2018 through May 2019. I'm looking forward to cutting my grass at 2"-3"+ for a change.

I need some help on cool season weed management. I am pretty sure very few of my herbicides are cool season grass friendly.

How do you guys control winter annuals, and most importantly, annual bluegrass, in a rye grass lawn? My plan is smoke out the rye in May 2019 with a combo of glyphosate and trifloxysulfuron (monument).

My existing herbicide collection includes: Three-way amine, Crossbow (2,4-d and triclopyr ester), Monument 75WG, Celsius, Princep 4L, glyphosate, fluazifop, and prodiamine. Aside from the prodiamine, I think the first two are the only viable contenders which will help with broadleaf control. Any options for grassy weed control? Thank you.


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## Green (Dec 24, 2017)

I'm not sure if you can use cool-season herbicides on a dormant warm-season lawn overseeded with cool-season grass. That's the first question that needs to be answered...


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## Turfguy93 (Aug 30, 2017)

As for controlling annual bluegrass in ryegrass your best bets post emergent are velocity and prograss, for winter annual weeds if you apply prodiamine and gallery 6-8 weeks after your ryegrass germinates you shouldn't have many annual weeds to deal with. I would say to use 4oz/A rate of tenacity when you seed the rye but I'm not sure what effect that will have on dormant Bermuda. Your 24D triclopyr ester should work for the winter annual weeds in late winter early spring if any make it through the PreM barrier.


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## g-man (Jun 15, 2017)

I think you timing is off. To kill the bermuda it will need round up when it is growing. Multiple rounds of round up and it will still be a challenge.

I'm assuming you will you rake/remove the bermuda to get the soil exposed and then seed with rye. If so, then tenacity at seed down should control the poa annua. Then do a light dose of preM (after 2 mows) to cover until march/april. A small bottle of weed b gon will be enough for any other weed. I would wait until almost october for seed down in your weather (below 80F).

@Iriasj2009 killed his bermuda last season. Check out his reno thread.


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## Movingshrub (Jun 12, 2017)

Green said:


> I'm not sure if you can use cool-season herbicides on a dormant warm-season lawn overseeded with cool-season grass. That's the first question that needs to be answered...


Understood, however, in this case, I don't expect the warm season grass to be dormant, I expect it to be dead.


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## Movingshrub (Jun 12, 2017)

Turfguy93 said:


> As for controlling annual bluegrass in ryegrass your best bets post emergent are velocity and prograss, for winter annual weeds if you apply prodiamine and gallery 6-8 weeks after your ryegrass germinates you shouldn't have many annual weeds to deal with. I would say to use 4oz/A rate of tenacity when you seed the rye but I'm not sure what effect that will have on dormant Bermuda. Your 24D triclopyr ester should work for the winter annual weeds in late winter early spring if any make it through the PreM barrier.


I'm looking for some guidance on when to apply the prodiamine. I've seen guidance from 8-10 weeks before seeding and 60 days after.

I understand isoxaben for the broadleaf weeds but I assume I can control those with the 2,4-D and Triclopyr mixture.


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## Movingshrub (Jun 12, 2017)

g-man said:


> I think you timing is off. To kill the bermuda it will need round up when it is growing. Multiple rounds of round up and it will still be a challenge.
> 
> I'm assuming you will you rake/remove the bermuda to get the soil exposed and then seed with rye. If so, then tenacity at seed down should control the poa annua. Then do a light dose of preM (after 2 mows) to cover until march/april. A small bottle of weed b gon will be enough for any other weed. I would wait until almost october for seed down in your weather (below 80F).
> 
> Iriasj2009 killed his bermuda last season. Check out his reno thread.


Ignoring the rye grass for a moment, my plan is to apply multiple apps of glyphosate and fluazifop to kill the bermuda grass this summer and then using a power rake in May to do the surface prep prior to the new grass going down.

My assumption is that I can apply rye seed into dead Bermuda grass debris, but I can't apply Bermuda sprigs onto dead rye grass, so the dead rye grass would have to go away in May.

The average first frost for Huntsville, AL is Oct 21st-31st. I assumed I needed to seed about 30 days before the expected frost date. However, the average temps start to tail off late Sep and early Oct so I may push it back a week or two.


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## Turfguy93 (Aug 30, 2017)

Movingshrub said:


> Turfguy93 said:
> 
> 
> > As for controlling annual bluegrass in ryegrass your best bets post emergent are velocity and prograss, for winter annual weeds if you apply prodiamine and gallery 6-8 weeks after your ryegrass germinates you shouldn't have many annual weeds to deal with. I would say to use 4oz/A rate of tenacity when you seed the rye but I'm not sure what effect that will have on dormant Bermuda. Your 24D triclopyr ester should work for the winter annual weeds in late winter early spring if any make it through the PreM barrier.
> ...


I've always went by the label which I believe is 60 days, but ryegrass establishes so fast and you plan on killing it anyways that you could apply it after you've mowed the grass 4-5 times.


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## Green (Dec 24, 2017)

Movingshrub said:


> Green said:
> 
> 
> > I'm not sure if you can use cool-season herbicides on a dormant warm-season lawn overseeded with cool-season grass. That's the first question that needs to be answered...
> ...


Ok. I see. In that case, Tenacity is a must-have. It gets things that 2.4-D or Triclopyr won't touch. With just those three, you can do a heck of a lot and have a weed-free lawn.

Still not totally clear on what you're doing, though. Killing Bermuda/mix and planting PR? And then killing the PR?? And replacing with...Bermuda?

If you're not going to have PR long, no point in buying Tenacity. It's not usable on Bermuda. St. Augustine would be a different story.


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## Movingshrub (Jun 12, 2017)

Green said:


> Still not totally clear on what you're doing, though. Killing Bermuda/mix and planting PR? And then killing the PR?? And replacing with...Bermuda?


I'm doing exactly what you listed.

My current front yard is a mixture of hybrid Bermuda, common Bermuda, and zoysia - the goal is to end up mono-strand with one type of hybrid Bermuda; the yard looks like a quilt sewn together with non-complementary patches.

To get a complete kill on Bermuda, I'll be spending this year trying to kill it so that I don't end up with a partial kill, resulting in a hybrid and common mixture. Generally speaking, the goal on warm season is one cultivar.

The rye grass is for erosion management and partially just for the fun of seeing how it looks, knowing full well that everything is going to be replaced in June 2019.

I think I've got a pretty good handle on broadleaf management. I just wasn't sure if there was any suggested approach for controlling grassy weeds. Considering the short time period for having a cool season lawn, I'm probably going to pass on the tenacity. Sounds like my option is basically just to live with any poa annua or poa triv that shows up.


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## Green (Dec 24, 2017)

Movingshrub said:


> Sounds like my option is basically just to live with any poa annua or poa triv that shows up.


And hopefully kill any that does show up before the heat makes it go dormant! Otherwise, it'll keep coming back in the cooler weather, each year.

I would strongly suggest getting a Poa-free turf-type perennial ryegrass blend to reduce the chance of that happening. The only one I know of is the "Champion GQ" blend by SRO, and available through Hogan. There may be others. But, just because a seed lot has 0.00 weed and other crop, does not mean it's definitely Poa free. You do reduce the chance even more in theory with a blend that states it is free of it.


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