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Thumb of Michigan | I'm going to try to explain what and why we do some things "here" spraying without confusing myself and everyone else. Bet I fail at that, though.
Surfactants- explained very well already. They don't affect the cuticle of the leaf as far as "burning through it". For me, when in doubt, I use a surfactant when posting. That is, unless the label forbids it.
Oils- There are at least 3 kinds I know of, and probably more than that, readily available. MSO (already talked about), your regular run of the mill petroleum based stuff, and ESO (ethylated seed oil). At one time, I was using a lot of ESO, I liked that real well for some applications. Of all the oils, I have had real good luck with ESO and glyphosate in cool temps. I don't like it when it gets above 70 drgrees, and haven't used it in a few years anyway.
Our first foray with crop oil was back when you could buy the "real deal", whatever that was. My dad still complains that we can't buy the old stuff, again whatever it was. Because of our pH and rotations, we can't use more than about 3/4# of atrazine per year. Before glyphosate was available, that was about the only thing that would hold quack back a little. We use to use 3/4# of atrazine and something like a gallon/acre of the old crop oil post. Sort of made 3/4# act like a pound and a half. Maybe the oil was some nasty by product from somewhere, I have no clue. But it worked great. Local dealers all had 20,000 gal tanks full of it.
MSO's really puzzle me. Many custom applicators here use them. The sugar companies promote them in the post sprays. Burns the hell out of everything almost immediatley. Lots of crop response in the wrong conditions, and in my experiance, I've ended up with very mad weeds that are really hard to kill the next time. If conditions are right, it burns the top growth of the weed so quickly that theres not much chem intake into the target. If you have weather extremes - too cold or too hot- it may be OK. With the chems I use, the crop response can be pretty bad under the same conditions. Some chems just won't work w/o MSO, and since I don't have any experiance with your crops, I'd talk to someone else about that sort of thing.
ESO's tend to not burn the weed or the crop. I had some unpredictable things happen a couple of times, so I just use regular stuff now if it calls for oil. I may have gotten a bad batch of ESO, in fact I'm pretty sure I did, so I quit them. I think the concept of how they work is just fine, though. Giving your weeds (or your crop) a flash burn isn't always a good thing, ESO's tend to not do that.
As a rule of thumb, any of the oils combined with any growth regulator will just make you puke when you check your crop out a day or so after spraying. I have had people tell me that it doesn't ultimately hurt the crop. Can't believe it adds yield, either.
AMS- I wouldn't dream of going out and spraying glyphosate w/o AMS. Of course, we have very hard water with lots of bad stuff in it. AMS grabs right onto the nasty stuff before it gets a chance to grab right onto your glyphosate. If you have a way to handle rain water, then you don't need AMS. Don't ever, under any circumstances, get your H2O out of a ditch, stream, pond, etc. Use well water only. Glyphosate is de-activated by soil particles. If you dump glyphosate into a tank with soil particles in it all ready, you're just out sight seeing when you're spraying. Your glyphosate is tied up before you start.
Temp inversions were explained very well already, but heres the rule of thumb I use when spraying. If the temp plus humidity adds up to 150, better park the sprayer. First thing is, you probably have a situation where chems may move off target. Obviously depends on the chem. Second thing is, your target weed is probably shut down for the day. Sort of kind of the way GDU's are calculated- no accumulation above somewhere between 85 and 90 degrees. I don't remember now. Anyway, your weed gets defensive just like your crop. Pores all shut down and its not interested in doing anything but hanging out until it cools down. But keep in mind, my temps and humidity is almost identical during spraying season. I can honestly say that I've never sprayed at anything below 30% humidity, so the rule of 150 may have zero bearing on your results. Just throwing it out there to consider. Spraying at night usually avoids this, except some weeds go to sleep at night just like we're supposed to. We have had some pretty nasty crop responce depending on the crop and the chem spraying too close to dark. If it works in your situation, I'd go for it, though. I know lots of areas of the country doesn't get calm winds till the sun sets.
I heard Ron from Illinois at a No-till conference a few years ago. He gave an excellant talk on herbs, additives and such, hope he weighs in here. He's probably forgotten more than I'll ever know. In fact, I'm sure him and most others here have. | |
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Spraying question.........bear with me........crop oil and surfactant.
