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Question about spraying and ambient air temperature

1K views 7 replies 5 participants last post by  takervader 
#1 ·
If the label of a herbicide says, for example 'do not spray above 90F', does that mean do not spray if the current air temperature is 90+, or if the air temperature is expected to reach 90F that day? I usually only spot spray so it isn't as critical, but two of my neighbors want me to broadcast their yards this fall and I don't want to burn their lawns. Our 3 day forecast is highs between 85-88 and night time lows in the low 60s. There will also be 4 days with chances of rain to finish the week (same temps). On one yard I'm planning to spray (generic) T-zone and the other I will spray a 3-way with quinclorac mixed in.

Another basic question I have that I have been seeing conflicting information on is how to actually mix the chemical in your sprayer/tank. Say I'm mixing 1 gallon (128oz) of water and 3oz of herbicide. Should I end up with a final volume of 128oz (so, I mix 125oz of water and 3oz of herbicide) or should I have a final volume of 131oz (128oz + 3oz). This question bothers me because it is so basic but I have seen answers confirming both.

Thanks again for all the help!
 
#2 ·
Another question I have and forgot to include is in regards to aerating. Should I broadcast before or after aeration? I'm assuming it's before but I want to be sure. The herbicide labels say to way 2 weeks after application to overseed but makes no mention to aeration. Thanks again!
 
#3 ·
Yes, your final solution should equal 128 ounces. Not critical.
However 3 ounces does not seem like much. A typical hand sprayer applies about 1 to 2 quarts per thousand sqft.
I think you are Ok to spray as long as there are a few hours before it gets over 90 degrees F. But its cool in Omaha, right?
And should you broadcast before or after aeration? Broadcast herbicide? Pre-emergent?
Or broadcast seed?
I do not think it would make any difference if the seed went down first--before aeration. However, opinions vary. Very difficult to prove one way or the other. If anyone has proof--or data from university research--they would have published it or let us know in an online source, such as "Lawnsite.com".
 
#4 ·
Thank you for your quick response and helping me sort this out - I was just using the 3oz of herbicide as a rough number for the example but you answered my question perfectly. I use a 5g backpack to broadcast spray so it was easier for me to use a single gallon as an example.

As far as my question about aerating I was referring to broadcast spraying herbicide, sorry, I meant to include that information.

So, my question is about whether or not it is OK to broadcast herbicide before or after aerating and if there are any timing intervals I should be aware of. eg. spray then aerate 2 days later, aerate then spray a week later, etc. (I may still not be making sense...can I broadcast spray at the same time I aerate, the day, before, the day after?)

The product labels on the herbicides say to wait 2 weeks after application to spread seed but makes no mention of whether or not aeration can have an impact on the herbicide application.

We're having a bit of a warm spell in Omaha at the moment but our night time temps are high 50s and low 60s. But, if you were asking about our grass varieties it is almost entirely cool season grasses with the occasional zoysia lawns here and there.



Thank you again!
 
#5 ·
I do not know--my guess is that aeration would have no effect on herbicide effectiveness.
Maybe someone else has experience with this idea.
I picture holes punched in dandelions. Maybe in clumps of clover. Picture a spurge or creeping charlie stem cut in half. No problem.

Temp is 62 F here.
 
#6 ·
Older thread I know. My best hypothesis would be depends on what mode the herbicide works. If it is leaf only np soil action it shouldn't I guess theoretically matter. If it is soil active, maybe like your sulfosufurons you might get 'better" soil action but the primary mode of op is still through leaf uptake. Overall I don't think and can't figure that it matters.
 
#8 ·
If it says not to apply over 90F, I definitely will not apply in the morning or midday if its expected to hit 90 at all that day. I have risked it in the early evenings, say 5-6pm.

Generally if it says not to apply at 90, i will not apply at all on a day that reaches 90 at any time during the day. I will switch 3-way herbicides in summer here to Celsius for that reason. Once we get close to those temps i dial back certain rates of things I know will damage the turf, before I switch.

If its 80 today and supposed to be 90 tomorrow, i would also dial back if I knew there was no rain or irrigation between then.
 
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