PDA

View Full Version : Hot temperatures and herbicide


RigglePLC
08-01-2011, 02:48 PM
I have heard several people comment that they do not spray weed at high temperatures for fear of turf damage and fear that the weeds would not be killed. Our neighbors to the south seem to think 90 degrees is fine. Therefore...
I decided to test the theory on my vacant lot--I mean at the Micro Turfgrass Research Center. But then it got slight cooler so it was only a humid 93 degrees temperature at the time of the test and it has been about 90 to 92 as a high in the last few days. 33 degrees Celsius. Heavy rain a few days ago--soil was moist. Rye, blue and fine fescue.
I sprayed a circle 13.5 inches in diameter, (equals one square foot). I sprayed spots for one second, 3 seconds and 5 seconds. Simulating about 1 times label rate, 3 times, and 5 times label rate. One second is about a third of an ounce of spray solution.

I sprayed:
Lesco Eliminate
Gordon's T-Zone
BASF Drive

Thus far at 36 hours, no injury to the grass. Slight effects on the few weeds in the spots.

I also treated poison ivy, and a few spots of weedy trees and brush nearby with Drive. Killed a few inches of a wild grapevine. Injured a bit of black locust. No visible effect on poison ivy, nor mulberry, nor box elder.

Stay tuned.

Laner
08-01-2011, 04:11 PM
I can confirm slight turf damage from applying Trimec 992 at 82 degrees at time of app with full sun and no rain for 6 days. This was checked 5 days after app. Grass displayed yellowing. Should come back fine with rain but still raised concern.
Posted via Mobile Device

lawn king
08-01-2011, 04:44 PM
This time of year (for the most part) we go to a full rate quinclorac, 1/3 rate eliminate, & wetting agent. Its very hot here in july & august & this combo is very stable in the hotter temps. This combo is good for a strong knockdown on clover, spurge, and crabgrass. When things cool down after labor day we will change up our formulation.

grassman177
08-01-2011, 05:57 PM
waiting fo the temps to drop here. 102-106 today and just as or hotter tomorrow. not too shabby huh

DA Quality Lawn & YS
08-01-2011, 06:40 PM
Full sun does seem to have an effect on apps in hot weather, no?

Smallaxe
08-01-2011, 07:14 PM
Drought plus heat on sandy soil, full sun... MN, WI, and MI really haven't had drought during July... Just oppressive heat and humidity, from the midwestern POV anyways...
How's IL anyway...? :)

vencops
08-01-2011, 07:33 PM
Question:

We have cool season grasses, for the most part, here. Since my spray career is in its' infancy, I admit to being gun-shy on risking turf damage, this time of year.

But, I also have to think.....

Let's say I'm successful in killing out the undesirables in my customer's lawns.

What now? Over-seed?

I could be completely naive...or, just plain ignorant. But, I'm not going to kill anything, until I can replace it with something better. And, I'm not thinking August in NC is the time to sew grass.

RigglePLC
08-01-2011, 10:23 PM
I have never had to seed where the weeds were killed. Its gradual and the grass fills-in--usually. Anyway the customers will call if there are weeds in the grass.
I hate spurge.

vencops
08-01-2011, 10:36 PM
Crabgrass - I agree. I'm tempted to spot-spray these, now, also.

Bermuda grass? It's a PITA, here. If I killed out bermuda patches, now.....I'd have bare spots. I'm seriously wondering if total control of this scourge is possible (here).

I don't really have any other weeds to speak of in my high-end (the ones where I spray) lawns. I'm not saying there's NO other weeds. There's just not anything to get upset over.

cgaengineer
08-01-2011, 10:49 PM
Your southern friends have dead fescue at this time of the season anyway...if its not dead its damn near it! Anything alive right now is bermuda and you can just about spray it with RU and not kill it...it may stunt it, but it likely will come back.

That being said, I do not use 3 way on bermuda in the heat, but I'll spray celcius all day long in the 90's...even on some non-irrigated lawns. Depends on the lawns health.
Posted via Mobile Device

Smallaxe
08-01-2011, 10:58 PM
If Bermuda and/or St. Augustine were lawn grasses... I'd agree with you guys... :)

vencops
08-01-2011, 11:18 PM
I've been looking at the Drive XLR8 label. It looks like a great product for my purpose (spot-treating CG). Like I said, earlier, though.....the temps sppok me a little.

I don't see any recommendations on the label. I did read not to irrigate for 24hrs. after application. That's not a problem.

If you were me, and you were gonna try this......would you do your spraying in the evening hours? Would the fact it's reaching 90's in the daytime and low 70's at night bother you? Humidity is high, all the time, currently.

If I go this route, I'm naturally going to do some test spots.

Thanks for your help. I did do a search. I think Diamond's in a similar "boat". Would love to hear how it's going for him (hint).

ted putnam
08-02-2011, 12:48 AM
If Bermuda and/or St. Augustine were lawn grasses... I'd agree with you guys... :)

They are......In God's Country:laugh::drinkup:

waiting fo the temps to drop here. 102-106 today and just as or hotter tomorrow. not too shabby huh

Same here, It was 109 in Ft. Smith today. They will not give us a set temp for the next 4 days, only a range. Somewhere between 101 and 105 with Heat indexes of 115+. I will be out but have given my help(part time) the rest of the week off. The wife's not very happy about me being out in it though.

Smallaxe
08-02-2011, 09:36 AM
They are......In God's Country:laugh::drinkup:



Same here, It was 109 in Ft. Smith today. They will not give us a set temp for the next 4 days, only a range. Somewhere between 101 and 105 with Heat indexes of 115+. I will be out but have given my help(part time) the rest of the week off. The wife's not very happy about me being out in it though.

Just stay alive Ted... we are in the mid-high 80's with the humdity and no breeze and IF I go out I'll be quitting at noon...
Every episode of heat stroke weakens the body to a point it will never fully recover... they've added up over the years and now I play it safe...

grassman177
08-02-2011, 02:01 PM
yikes, be careful with yourself.

i dont see an end yet so i may start treating well irrigated lawns only soon, but i am giving it another week to cool off a bit. one can hope

RigglePLC
08-02-2011, 04:01 PM
The label for "Surge" herbicide says do not boadcast apply at temps over 90, and" some injury can be expected when spot spraying at temperatures over 90."

Horsepower herbicide (similar to Lesco Eliminate), says on the label do not apply at temperature over 90.
Redzone: "do not broadcast at temps over 85.
Eliminate "Avoid excessively hot"
Eliminate LO: limit 90

RigglePLC
08-02-2011, 04:35 PM
Lesco Three-way Selective: spray limit is 90 degrees.
Gordon's Trimec: "Schedule applications when temperatures are between 60 and 90 and there is good soil moisture."

americanlawn
08-02-2011, 05:30 PM
I was there over Independence Day weekend, then in Fayetteville. Spoke with my Fort Smith cousin a bit ago (Howard Hill Road). Today is even hotter than yesterday. Lawns are brown unless they get water or grow in shade (bermuda) Heat indexes here in Iowa are +/- 110. Yikes.

We see no turf damage here (cool season turf) when we use "Chaser" BWC during hot weather. It's an ester formulation of 2,4-D and triclopyr.

Amine 3-ways are much more likely to cause turf damage during hot temps.

Chaser costs more than double, but it's less stressful to cool season turf during hot weather compared to common 3-ways. IMO



They are......In God's Country:laugh::drinkup:



Same here, It was 109 in Ft. Smith today. They will not give us a set temp for the next 4 days, only a range. Somewhere between 101 and 105 with Heat indexes of 115+. I will be out but have given my help(part time) the rest of the week off. The wife's not very happy about me being out in it though.

grassman177
08-02-2011, 07:27 PM
i have used chaser before, it was good, but we used it in cool weather, and amine in wamer due to volitization of esters is more prone in hot weather.

am i wrong on that?

RigglePLC
08-02-2011, 09:42 PM
Chaser according to this comes in two forms--the ester and the acid. The acid is probably neutralized out by being in the water-soluble salt form.

http://www.cdms.net/ldat/ld5CR000.pdf

So you are correct.

greendoctor
08-03-2011, 03:33 AM
I was there over Independence Day weekend, then in Fayetteville. Spoke with my Fort Smith cousin a bit ago (Howard Hill Road). Today is even hotter than yesterday. Lawns are brown unless they get water or grow in shade (bermuda) Heat indexes here in Iowa are +/- 110. Yikes.

We see no turf damage here (cool season turf) when we use "Chaser" BWC during hot weather. It's an ester formulation of 2,4-D and triclopyr.

Amine 3-ways are much more likely to cause turf damage during hot temps.

Chaser costs more than double, but it's less stressful to cool season turf during hot weather compared to common 3-ways. IMO

It is interesting that you discovered that. I deal with highly maintained warm season grasses. The kind you are only supposed to use low 2.4-D sensitive turf formula Three Ways such as Trimec Southern. I get better weed control and minimal turf injury if I use a moderate rate of 2,4-D ester and a low rate of dicamba or else the ready to go Speedzone Southern which is 2,4-D ester based. The low 2,4-D sensitive grass formulas are really high in MCPP amine, which does little to the usual warm season weeds such as oxalis and spurge, but it sure hits the turf hard. Regular Three Way is no better because I find that I need more amine to kill the same weed vs the ester. The only time I ever had the 2,4-D ester volatilize and damage off target vegetation is when I sprayed on a day where temperature was almost equal to humidity and there was no wind as in 90F/80% RH. I consider a week of constant 5-10 MPH winds, low humidity and moderate temperatures a better time to use ester.

cgaengineer
08-03-2011, 06:52 PM
Crabgrass - I agree. I'm tempted to spot-spray these, now, also.

Bermuda grass? It's a PITA, here. If I killed out bermuda patches, now.....I'd have bare spots. I'm seriously wondering if total control of this scourge is possible (here).

I don't really have any other weeds to speak of in my high-end (the ones where I spray) lawns. I'm not saying there's NO other weeds. There's just not anything to get upset over.

Scourge...LOL....that's funny to a southern guy...how dare you insult my grass!
Posted via Mobile Device

vencops
08-03-2011, 07:35 PM
Hey....lol...I said (here)!

americanlawn
08-03-2011, 07:35 PM
Here's what I cannot figure out...folks say to avoid 'esters' when it's warm. Problem is, that's when the hard-to-kill weeds appear. (Good luck with weed control using amines then). This never made sense to me. :confused:

Nuther thing is: LD50 of Chaser ester is "extremely low". (oral = >5000) which is safer compared to 3-way amines according to manufacturer labels.

We actually STOPPED using amine 3-ways during hot weather decades ago due to tip burn and other turf damage.....yet most say to use "amines" during hot weather. To me this is back a$$wards.

It is interesting that you discovered that. I deal with highly maintained warm season grasses. The kind you are only supposed to use low 2.4-D sensitive turf formula Three Ways such as Trimec Southern. I get better weed control and minimal turf injury if I use a moderate rate of 2,4-D ester and a low rate of dicamba or else the ready to go Speedzone Southern which is 2,4-D ester based. The low 2,4-D sensitive grass formulas are really high in MCPP amine, which does little to the usual warm season weeds such as oxalis and spurge, but it sure hits the turf hard. Regular Three Way is no better because I find that I need more amine to kill the same weed vs the ester. The only time I ever had the 2,4-D ester volatilize and damage off target vegetation is when I sprayed on a day where temperature was almost equal to humidity and there was no wind as in 90F/80% RH. I consider a week of constant 5-10 MPH winds, low humidity and moderate temperatures a better time to use ester.

ted putnam
08-03-2011, 10:00 PM
Official temps have been recorded each day in Little Rock since 1870. Today was the all time RECORD. 114 degrees with a heat index of about 125. I drank 2 gals of ice water, soaked my head and hat at customers homes every other stop, sweated like a *****(HORR) and still had a heat headache by 3PM. Couldn't take any more and stopped work at 3:30

Hogjaw
08-03-2011, 10:39 PM
Ted,

You better sit down and think about weather seriously instead of haphazardly(sp?)!!!!!!!!!!!!

It ain't worth it.

Worked Monday morn from 6 to 9:30 am and quit for day, off yesterday, sprayed MSMA on one this morning and quit........kinda nice sitting instead of running for a change.

Take care.

According to NWS no relief in sight for us for days to come. Those west of us are really hurting.

ted putnam
08-03-2011, 11:04 PM
Ted,

You better sit down and think about weather seriously instead of haphazardly(sp?)!!!!!!!!!!!!

It ain't worth it.

Worked Monday morn from 6 to 9:30 am and quit for day, off yesterday, sprayed MSMA on one this morning and quit........kinda nice sitting instead of running for a change.

Take care.

According to NWS no relief in sight for us for days to come. Those west of us are really hurting.

Thanks Jimmy. I took Monday and Tuesday off. Temps were 102-104. Problem is, I'm a workaholic and sitting around drives me nuts. They were expecting around 106 today so 114 was a surprise for everyone. My truck said 112 at 1:30PM but I can never trust it for being accurate. I didn't know the official temp until I heard it on the radio on the way home about 4PM. I'm sure it was hotter in Ft. Smith than here in Central part of state. Texas is suffering badly. They are buying round bales from local growers for $78/bale just to keep their cattle alive. My brother-in-law sold all 70 head of cattle he had the other day because his pasture is burned up. No grazing now and no hay for the winter. If we don't get rain soon, we'll be in the same boat... Thanks for your concern. I promise, tomorrow will be a slower, shorter day. Take care.

greendoctor
08-04-2011, 03:12 AM
Here's what I cannot figure out...folks say to avoid 'esters' when it's warm. Problem is, that's when the hard-to-kill weeds appear. (Good luck with weed control using amines then). This never made sense to me. :confused:

Nuther thing is: LD50 of Chaser ester is "extremely low". (oral = >5000) which is safer compared to 3-way amines according to manufacturer labels.

We actually STOPPED using amine 3-ways during hot weather decades ago due to tip burn and other turf damage.....yet most say to use "amines" during hot weather. To me this is back a$$wards.

I will not forget when I turned 1/4 acre of centipede grass fluorescent yellow, then shades of brown 20 years ago because I applied sensitive grass formula Three Way amine to it. I was new to the industry and did not know that a low rate of 2,4-D ester + a trace of dicamba would be less harmful. Worst part of the whole experience was how the spurge and clover was less damaged than the turf. This was applied according to label rates using calibrated equipment.

I am sure you also understand when the risk of vapor damage is greatest. Now I do something pretty brave considering that it is seldom the textbook less than 80 and no wind. I broadcast. No spot spraying. This has never caused me problems. On the other hand, If I picked a day with zero wind, chances are it is going to be pushing the mid 90s and humidity will be astronomical. Perfect conditions for the ester to distil off the treated areas and give surrounding trees a 2,4-D fumigation. The flip side of this is when it has been cool, cloudy and raining for the past month. Amines do not penetrate fast enough and they seem to need sun in order to work. Ester will still work even if the sun will not be out for the rest of the month and it rains an hour after application.

You should be so thankful that your hard to kill weeds are annual and just came up that year. I get spurge and oxalis that might have been growing in the heat and humidity for over 12 months. Nothing but esters will even begin to phase those weeds. I also have to spike the ester with some sulfonylurea herbicides or the weeds tend to regrow from the roots.

I have to love the labeling on regular Three Way, especially when it comes time to convince a client or concerned bystander that what I am doing is safe for them. "Danger, causes irreversible eye damage". It is not the 2,4-D that is the hazard. It is the dimethylamine or monoethanolamine or diethanolamine or other amine used as the solvent for the phenoxy herbicide. I think I mentioned previously that monoethanolamine is frequently used as floor wax stripper, oven cleaner or the kind of degreasers that are restricted to industrial use only. The labeling on Speedzone is much less ominous. No danger label or warnings about irreversible damage to anything.

RigglePLC
08-04-2011, 10:16 AM
I tested three herbicides in the heat. (94 degreess was the best I could do around here-next 3 days were 90).
I tested Lesco Eliminate, Gordon's T-Zone and Drive. I applied with hand sprayers for one second, 3 seconds and 5 seconds. About label rate, 3 times and 5 times label rate.

After 4 days there was no visible injury or phytotoxicity to grass. (Cool season grass.)

T-Zone killed clover as did Eliminate. Drive killed clover and crabgrass.

Good questions about esters and amines. Green is right; the inert ingredients in the amines are very dangerous to the eyes, therefore the "Danger Warning" label. And the esters are relatively less dangerous.

And good questions guys. Regarding grass and vapor drift, can esters be safely applied in hot weather (how hot).