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Atrazine vs. Simazine for pre-emergent us on Bermuda grass

44K views 15 replies 11 participants last post by  SOONER GREEN 
#1 ·
I am trying trying to figure out the pro's and con's between Atazine and Simazine for usage as a pre-emergent on Bermuda. What is big difference between the two as far as effectiveness and weeds controlled? I know that Atrazine has some post-emergent weed control while Simazine does not but what are the other big differences? Also, how does Atrazine and/or Simazine compare to Pendamethalin as far as a pre-emergent is concerned? Does Atrazine/Simazine cover some weeds that Pendamethalin doesn't control?
 
#2 ·
Neither one are true pre-emergent. Yes, they will fry the hair roots on germinating seed for a short period of time but they go quickly into the ground. They are meant for post-emergent weeds. They have got to be respected as to temperature, especially Simazine. Read the label. For a real pre-em use Gallery or Dimension; gallery being the least harmful to the root system. Roy
 
#3 ·
Neither one are true pre-emergent. Yes, they will fry the hair roots on germinating seed for a short period of time but they go quickly into the ground. They are meant for post-emergent weeds. They have got to be respected as to temperature, especially Simazine. Read the label. For a real pre-em use Gallery or Dimension; gallery being the least harmful to the root system. Roy
I would have to disagree.

I'm not an expert on the differences between the two, but simazine used properly in the fall is a great solution for preventing annual bluegrass/henbit, etc., for me in my area.

Want proof of how it can be used properly, take a look at my lawns right now. My fall application is straight Simazine, applied at 1.5 qts. per acre. Then, I follow in the spring with Barricade/Simazine mix. Timing for me is Nov/Feb. Simazine has plenty of longevity for that type of timing.
 
#5 ·
Simazine is a spring and early summer application for me. Even on hybrid bermuda. That has to be qualified with the fact that I do not spray lawns that are without an irrigation system or are not fertilized by me. The height of cut is also important. Too high or too short and the grass is weak. Atrazine, on the other hand, is entirely different. Because of its different properties once it is applied, I do not use it on bermuda. Simazine is one of the options I use for goosegrass, smutgrass, paspalums, and various broadleaf weeds. It is a tool that I use to clean up lawns that have become mostly weeds.
 
#6 ·
I would have to disagree.

I'm not an expert on the differences between the two, but simazine used properly in the fall is a great solution for preventing annual bluegrass/henbit, etc., for me in my area.

Want proof of how it can be used properly, take a look at my lawns right now. My fall application is straight Simazine, applied at 1.5 qts. per acre. Then, I follow in the spring with Barricade/Simazine mix. Timing for me is Nov/Feb. Simazine has plenty of longevity for that type of timing.
Exactly what I do with mine Turfdoc with identical results. Ples Spradley (Arkansas State Plant Board)recommended that to a few of us that asked him in a small group having conversation. Watch that maximum annual use rate specified on the label! Other than that... excellent, affordable results.
 
#7 ·
Simazine is a spring and early summer application for me. Even on hybrid bermuda. That has to be qualified with the fact that I do not spray lawns that are without an irrigation system or are not fertilized by me. The height of cut is also important. Too high or too short and the grass is weak. Atrazine, on the other hand, is entirely different. Because of its different properties once it is applied, I do not use it on bermuda. Simazine is one of the options I use for goosegrass, smutgrass, paspalums, and various broadleaf weeds. It is a tool that I use to clean up lawns that have become mostly weeds.
Funny... I've seen entire lawns that were dead as a hammer except for a 1 inch strip around every sidewalk and driveway because TGCL used Atrazine to late in the Spring. Their local branch manager from one of the northern states didn't know any better. He just saw it on the fill sheets for Round 1 and filled the trucks with it. Killed whole routes of bermuda. That's why I've stressed in the past that the person in charge needs to know what they are doing... Atrazine...It can be BAD NEWS!
 
#8 ·
As far as I am concerned, atrazine on bermuda is a no go in my area period. Bermuda is never truly dormant here. It can be stressed from lack of sun or nights dropping to 60, but that is the exact time you will never apply a hot herbicide to bermuda if you know what you are doing. This is also why the idea of filling up a 500 gallon tank and hosing down everything with the same mix is not part of my practice. I can be visiting a bermuda, centipede, st augustine seashore paspalum, and zoysia lawn all in one day. A load containing atrazine would mean I owe people with bermuda or paspalum a new lawn, negating any time I saved by mixing a single tank.
 
#9 ·
Exactly what I do with mine Turfdoc with identical results. Ples Spradley (Arkansas State Plant Board)recommended that to a few of us that asked him in a small group having conversation. Watch that maximum annual use rate specified on the label! Other than that... excellent, affordable results.
that maximum annual use rate is tricky, Ted, I agree.

I push the envelope with it certainly. I use 1.5 qts/acre in the fall, and 0.5 in the spring, but probably put out a little heavy honestly.

I didn't notice any difference in 1.5 qts and 2.0 from the previous year, so, i'm going to back it down a little again next fall.
 
#10 ·
Atrazine does state on the label--"The label that I occupy" Use on Dormant Bermuda!
We used Simazine once as we were late in application due to heavy rains. The bermuda was semi-dormant and we treated for poa annua. The next week, it hit in the mid 80's in November, like it often does here and what do you know--------that Tifway 419 nearly died. It was sickly brown until the following spring. We had to apply 34-0-0 at 4 applications to bring it out of the root pruning it caused. Then we used 13-13-13, 16-16-16 and 32-3-7 on it to recover. This was at the lowest rate on the label.....
We never will use it again..............
Oh--The advice was from my supplier to use it and was not appreciated, however it was a lesson learned. It wasn't Lesco-- Northeast Arkansas sprayers know who I am talking about..
 
#11 ·
This table might help you out - http://msucares.com/lawn/lawn/table2a.pdf

If you are primarily concenced with crabgrass, choose a root inhibitor like pendimethalin, prodiamine, or dithiopyr.

Simazine does have some post emergent control. Simazine and Atrazine are photosynthetic inhibitors and can stunt tolerent grasses, but Atrazine seems to be more harsh.

Most people that I know use Simazine and metsulfuron or Simazine and a 3way product to take care of most winter annuals that are common in dormant bermuda.
 
#12 ·
Atrazine does state on the label--"The label that I occupy" Use on Dormant Bermuda!
We used Simazine once as we were late in application due to heavy rains. The bermuda was semi-dormant and we treated for poa annua. The next week, it hit in the mid 80's in November, like it often does here and what do you know--------that Tifway 419 nearly died. It was sickly brown until the following spring. We had to apply 34-0-0 at 4 applications to bring it out of the root pruning it caused. Then we used 13-13-13, 16-16-16 and 32-3-7 on it to recover. This was at the lowest rate on the label.....
We never will use it again..............
Oh--The advice was from my supplier to use it and was not appreciated, however it was a lesson learned. It wasn't Lesco-- Northeast Arkansas sprayers know who I am talking about..
The mistake was applying simazine to bermuda under stress from the weather not being able to make up its mind. Bermuda and other grasses labeled as tolerant metabolize simazine, breaking it down to nontoxic compounds. This process does not occur if the grass is almost dormant(slow metabolism), then a warm week, then cold again. If the grass were totally dormant with no chance of it waking back up until the simazine's life is over, that would have been ok. No uptake will occur in dormant grass. Simazine does not prune roots, it will kill off things completely. What you saw was grass plants totally killed and the surviving grass needing to grow back to fill in the lawn. Good thing you did not use Image under those circumstances.
 
#13 ·
Yo

Now that Atrazine is a RUP I have gotten away from it because of the paper work. My soil being sandy has never allowed Atrazine to stay around long enough to be a Pre Emerge. At one time it was not labelled for Bermuda or Bahia turf. However it is now and I seen Homeowners over apply it on both with no ill effects. If you apply it heavy enough to stunt Bermuda you also kill St Augustine. Atrazine IMHO is a Post emerge. BTW Oxisales and Beggar Weed think it is Fertilizer.
 
#14 ·
This table might help you out - http://msucares.com/lawn/lawn/table2a.pdf

If you are primarily concenced with crabgrass, choose a root inhibitor like pendimethalin, prodiamine, or dithiopyr.

Simazine does have some post emergent control. Simazine and Atrazine are photosynthetic inhibitors and can stunt tolerent grasses, but Atrazine seems to be more harsh.

Most people that I know use Simazine and metsulfuron or Simazine and a 3way product to take care of most winter annuals that are common in dormant bermuda.
I'm in zone 7 (Northern Alabama), would it be too late to apply simazine to kill out poa annua in a bermuda lawn.
 
#15 ·
In North MS, much of the poa on untreated properties is very mature. Simazine won't do a whole lot to seeded out poa. However, it will remove the young poa and weaken the older poa, thereby letting the warm season grass have a better chance at taking over. Simazine in the Fall and Winter is very beneficial to my lawns.
 
#16 ·
I guess we are fortunate here to be able to use simazine. I've sprayed it on bermuda every year since 1985 and it is one chemical that I can count on. The cost per acre is great.We mix it with a 3 way, apply both at 2 qt's / acre & the lawns are clean come spring. Never had a problem with it, you do need to lighten up on hybrids.
Atrazine isn't used much around here, but I know they do down in Texas, especially on St Augustine as a post. Dow has a new chemical called lockup that is an atrazine replacement.
 
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