Herbicide for St. Augustine during summer

nolo · Aug 22, 2017

I was reading some guidelines University of Florida for St. Augustine. It states that Atrazine or other herbicides shouldn't be used when air temperatures are over 85 degrees. It is 85 degrees or hotter all summer long here. Do you guys apply any herbicides in the summer months? What are you supposed to do as a post emergent?

RAlmaroad · Aug 22, 2017

nolo said:
I was reading some guidelines University of Florida for St. Augustine. It states that Atrazine or other herbicides shouldn't be used when air temperatures are over 85 degrees. It is 85 degrees or hotter all summer long here. Do you guys apply any herbicides in the summer months? What are you supposed to do as a post emergent?

St Augustine is a beautiful grass but loves nitrogen. Be careful there as it is also prone to many fungi. Make sure you get your pre-em out early enough to take care of weeds. Also pre-em (Gallery) can be used again in June. If you irrigate then the Gallery will not last as long and you will have to manage the Gallery according to your irrigation. Spring application will give you 6-8 weeks of good control but will start to decline. This may be all that you need. If somewhere in between applications of Gallery then check into using Celsius--a good choice. I've also had great success with Image--but it must be used when grass is growing well. Use both on the medium rate. Another good choice is Dismiss. Check out the label. Then around December is a great time to use Atrazine for winter weeds. Now remember that all of these are spray applied and good equipment must be used.

grassmasterswilson · Aug 22, 2017

RAlmaroad said:
St Augustine is a beautiful grass but loves nitrogen. Be careful there as it is also prone to many fungi. Make sure you get your pre-em out early enough to take care of weeds. Also pre-em (Gallery) can be used again in June. If you irrigate then the Gallery will not last as long and you will have to manage the Gallery according to your irrigation. Spring application will give you 6-8 weeks of good control but will start to decline. This may be all that you need. If somewhere in between applications of Gallery then check into using Celsius--a good choice. I've also had great success with Image--but it must be used when grass is growing well. Use both on the medium rate. Another good choice is Dismiss. Check out the label. Then around December is a great time to use Atrazine for winter weeds. Now remember that all of these are spray applied and good equipment must be used.

Are you using 1 lb of gallery and only getting 6-8 weeks out of it? I was gonna run it onncentipede at 1 lb gallery in march/April with a possible booster app of 1/2 lb 10 weeks later. It all depends on program pricing.

RAlmaroad · Aug 23, 2017

Can't remember my numbers but vaguely .03oz/K, however whatever was recommended on the label is what I used. Wouldn't run it too strong because of root pruning in the summer. Because of so irrigation on sandy soil or plain sand on the coast, any pre-em will quickly decline through leaching. Just have to look and keep a good log.

JustinFL · Aug 25, 2017

nolo said:
I was reading some guidelines University of Florida for St. Augustine. It states that Atrazine or other herbicides shouldn't be used when air temperatures are over 85 degrees. It is 85 degrees or hotter all summer long here. Do you guys apply any herbicides in the summer months? What are you supposed to do as a post emergent?

I'm in South Florida where it's 85+ like 10 months out of the year if not longer lol. And yes I do and treat St. Augustine. I don't use Atrazine though. I use Celcius and Blindside mainly and do get some stunting and burning of the tips sometimes, but nothing major. The mower takes off the burnt tips and normal growth resumes after a week or two.

FLpestandlawn · Nov 12, 2017

JustinFL said:
I'm in South Florida where it's 85+ like 10 months out of the year if not longer lol. And yes I do and treat St. Augustine. I don't use Atrazine though. I use Celcius and Blindside mainly and do get some stunting and burning of the tips sometimes, but nothing major. The mower takes off the burnt tips and normal growth resumes after a week or two.

What rate are you using Celcius for St augustine during the summer? I live in southwest florida and stunted some lawns I was trying to turn around using the medium rate in the July. From my experience it kills weeds (especially if you get a second application),but also slows down st augustine which the allows new weeds to grow in bare spots. Got any suggestions on a turn around program for weed filled yards down here?

BParsons · Dec 27, 2017

I am in the same boat . In Fl the 85 degree temp is a constant worry for me. I am always concerned about burning. I have used Manor (MSM) mixed with Octane and Basagran for my summer weed treatments for several years now. No burn issues to speak of. I have had an issue or two during late spring when its very dry out , but I also feel that was due to my addition of a surfactant. I no longer use it and have no problems. I use Manor at 1 line per 1000 sq ft on measure device , Octane at 1 dropper per 1000 sq ft and Basagran at .75 oz per 1000 Sq Ft I have purchased several Bottles of Blindside to use this summer to change it up a bit , but I am still worried about burning.

greendoctor · Dec 27, 2017

Blindside is going to burn a lot. Especially when used in a way that the Metsulfuron component will be effective. I avoid Dismiss on St Augustine unless scorching is acceptable. It is not like the other grasses where I can mow off the damage. The equivalent to Blindside is MSM+Dismiss. I would never buy Blindside because there are times when I want to leave out Sulfentrazone. Then there are times when I want to leave out MSM.

FLpestandlawn · Dec 29, 2017

FLpestandlawn said:
What rate are you using Celcius for St augustine during the summer? I live in southwest florida and stunted some lawns I was trying to turn around using the medium rate in the July. From my experience it kills weeds (especially if you get a second application),but also slows down st augustine which the allows new weeds to grow in bare spots. Got any suggestions on a turn around program for weed filled yards down here?

I have the same exact experience with Celsius. How the heck do you turn around a yard with lots of weeds, without stunting the St. Augustine, and allowing weeds to just grow back? I've also noticed Celsius gives the st augustine grey leaf spot .
I'm trying to figure out a good plan of Attack for turnaround yards - maybe more frequent visits with spot spraying ? Any suggestion for us south Florida guys would be great !

FLpestandlawn · Dec 29, 2017

greendoctor said:
Blindside is going to burn a lot. Especially when used in a way that the Metsulfuron component will be effective. I avoid Dismiss on St Augustine unless scorching is acceptable. It is not like the other grasses where I can mow off the damage. The equivalent to Blindside is MSM+Dismiss. I would never buy Blindside because there are times when I want to leave out Sulfentrazone. Then there are times when I want to leave out MSM.

Could you elaborate on the times you would leave out MSM and Sulfentrazone? I have just started using Blindside this winter in south Florida and would not try it outside of cool temperatures. Will let you know how it went when I go back.Thanks by the way for the wealth of information you have posted.

greendoctor · Dec 29, 2017

MSM works better in warm weather. If I need foliar burndown with the MSM, I add moderate rates of Quicksilver. Sulfentrazone is specifically directed at Nutsedge and Kyllinga during cooler weather when Certainty or Monument are less effective. For the amount of potential burn it can cause, I do not think it is worth applying it in warm weather mixed with MSM. Furthermore, in the case of sedge infested lawns, they are on a program where 4 oz of Dismiss is applied at 30 days intervals. I do not want to ever apply that much MSM in one year. Even with my 12 month growing season. I cap applications at a total of 1 oz every 12 months.

jds912 · Dec 30, 2017

I wouldn't plan on spot spraying until you have the lawns pretty cleaned up. Blindside is harsh on St Augustine. I would never attempt to use it on centipede. I have applied the high rate to a weed infested St Augustine yard. It meltled most broad leaf weeds into mush. It turned the grass a shade of grey, then purple.Yard pulled through, except at overlapped areas. You should be able to clear up most weeds with a good pre emergent and a post mix of msm, Celsius and Quicksilver. Avenue South at just below application ratesat should be ok. Educating your customers will be paramount in cleaning up the lawn. Notify them it may get worse before it gets better. Cool thing about living in S. Florida, you can fertilizer the turf more than most places. You should be able to grow out any phytotoxicity that occurs. Fertilize before and after herbicide apps. Doveweed and crabgrass may be the only weeds you may need to roundup. Msm and Celsius, at the correct rates, mixed together, will kill annual crab in St Augustine. I have seen a superintendent pull it off. Phytoed the St Augustine, but didn't kill it. I need to ask what rates he used. Good luck.

greendoctor · Dec 30, 2017

jds912 said:
I wouldn't plan on spot spraying until you have the lawns pretty cleaned up. Blindside is harsh on St Augustine. I would never attempt to use it on centipede. I have applied the high rate to a weed infested St Augustine yard. It meltled most broad leaf weeds into mush. It turned the grass a shade of grey, then purple.Yard pulled through, except at overlapped areas. You should be able to clear up most weeds with a good pre emergent and a post mix of msm, Celsius and Quicksilver. Avenue South at just below application ratesat should be ok. Educating your customers will be paramount in cleaning up the lawn. Notify them it may get worse before it gets better. Cool thing about living in S. Florida, you can fertilizer the turf more than most places. You should be able to grow out any phytotoxicity that occurs. Fertilize before and after herbicide apps. Doveweed and crabgrass may be the only weeds you may need to roundup. Msm and Celsius, at the correct rates, mixed together, will kill annual crab in St Augustine. I have seen a superintendent pull it off. Phytoed the St Augustine, but didn't kill it. I need to ask what rates he used. Good luck.

I have applied MSM and Dismiss on Centipede. However, the MSM is limited to no more than 1/2 oz per acre and 4 oz per acre for the Dismiss. Quicksilver is a much safer burndown additive and as I said above, there is a specific circumstance when I would use Dismiss. I do not use it for general broadleaf weed control.

MSM actually affects a lot of grassy weeds. Does not surprise me that it would do something to Crabgrass. Legal, but not recommended because of how damaging it can be to the desirable turf is 1 oz MSM per acre. Think about soil texture/type, as well as nearby trees and shrubs that may have their root system in the sprayed area. Above 0.5 oz per acre, I know MSM as what is used to kill everything except the Bermuda in pastures and as a bare ground herbicide. If I had to guess, that golf super put down 1 oz MSM and 3 oz Celsius. Don't imagine anything but Bermuda or St Augustine surviving that.

Herbicide for St. Augustine during summer

nolo

RAlmaroad

grassmasterswilson

RAlmaroad

JustinFL

FLpestandlawn

BParsons

greendoctor

FLpestandlawn

FLpestandlawn

greendoctor

jds912

greendoctor

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