At what temp do you stop spraying ?

[shakerator]

21 degrees I've been told ?

Would you go at 25 if just strob as chlorthalonil (drop out triazole for later)

 

[principal skinner]

Light intensity more important than temperature imo. 25 degrees and cloudy-no problem. 22 degrees and unbroken sunshine then may stop.

 

[Sandy]

There going around here 27degrees and a howling wind madness!

 

[Brisel]

Epoxiconazole is known for causing tipping if applied on hot sunny days.

 

[Zippy768]

+1 for the sun over temp. 23/24 degrees here without a cloud in the sky. I wouldn't be spraying. People with more experience might know better though.

 

[Kidds]

There going around here 27 degrees and a howling wind madness!

Same here. Nuts!

For me, depends what I am spraying and what crop. Won't put anything on apples above 21°C and even have a thermometer in my cab to keep an eye on it.
Bright sunshine is the killer mind, cloudy and higher temps is OK but I know damned well if I took a chance the clouds would clear immediately.

 

[Chae1]

There going around here 27degrees and a howling wind madness!

Great hay making weather!

 

[Breakthru]

24-25C crop shuts down. That may be more or less whether its strong sunlight or overcast. What is the point of applying a systemic chemical if there is no chance of it being absorbed. I would be using 20-21C in direct sunlight as my top end.

 

[Chalky]

Agree about temperature-but assuming it does not rain, it will cool down & the chemical is still there-and will be taken in-will it not?

 

[Brisel]

Wouldn't that depend on the solvent still being there to help penetrate the cuticle? I'm sure the formulation boffins have thought of this.

 

[Breakthru]

Wouldn't that depend on the solvent still being there to help penetrate the cuticle? I'm sure the formulation boffins have thought of this.

Some of the labels stipulate 20C

 

[Hindsight]

Some of the labels stipulate 20C

Yes, but labels are also written by lawyers with an eye to litigious farmers grumbling and complaining about anything that might affect their crop.

 

[Breakthru]

Yes, but labels are also written by lawyers with an eye to litigious farmers grumbling and complaining about anything that might affect their crop.

Just possibly they may have found that the effectiveness of their active has reduced above 23-24C so to be safe are quoting 20-21C so that if you complain about ineffectiveness they will ask you what day and time you sprayed and say you were outside label parameters. It would have to be fairly obvious that if the science says crops shut down above a certain temp then systemics are unlikely to work as well as in ideal conditions. If you are not going to spray when its raining then why spray when the surface temperature of the leaf is in the high 30's.

 

[Farmer Miggins]

I recall Tom Robinson advocating laying a good old fashioned thermometer in the flag and checking the actual radiant temperature, as opposed to air temp. I would stop if radiant temp was 30 degrees and there is apocryphal evidence that water alone can scorch wheat at that temperature

 

[PSQ]

Quite a lot of yellowing in evidence on a few farms today, bright custard yellow on overlaps.

But I did see a few sprayers going about on Friday when temperatures were hitting 27 / 28 degrees. Wheat leaves were looking rolled and waxy, almost blue from a distance.

 

[Drillman]

Aircon is bust on sprayer tractor here so no spraying when it's hot.

 

[MrNoo]

Next door went last week and scorched the hell out their wheat, looks a right mess, not sure what they were applying, maybe a late dose of liquid fert or a T3, dont know but all the leaves are yellow. In that hot weather, I just did a load first thing in the morning then stopped, one late in the evening, rightly or wrongly.