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Discussion Starter · #1 ·
Can you have "too much" overlap?

If you park my sprayer on flat level surface, measure boom height, it is spot - on spec for the nozzles according to the book.

The reality is different though. Lots of rolling land, side hills, sometimes a dead furrow or something, and the booms are rarely equadistant from the ground from end to end. I've got a field with a disaster of pigweeds that my alfalfa didn't come up in. The plan is to spray it out and replant, but that's kind of beside the point. In the taller weeds/ grass especially, the spray kill is "striped" like it didn't overlap good. I see evidence of this in my most rolling corn field also. What will it hurt to raise it up a few inches?

*edit* Not just raise it up, but raise it up and leave it there. I don't want to go up and down, will it hurt anything back when it's on more level ground?
 

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Not too much overlap, just higher drift risk as booms raise.
I've also ran my boom a touch low this spray season but it didn't affect over 1/100 of 1% of the total spray area.
 

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You have probly factored this in already. Just remember the spray height should be from the top of your target not the ground.
 

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Discussion Starter · #7 ·
Yes, between nozzles, not between passes.

I guess my question comes down to what I have this year. There is quite an area toward the south of my field that the "target" was very tall, the rest of the field not so bad. If I have it at close to proper height over the tall targets, is there any detrimental effect, "too much overlap", where the targets are shorter? We aren't talking a hydraulic auto height here, we're talking bolts and clamps etc. . .

The taller stuff is green and brown atriped!
 

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The only detrimental affects of having the boom to high /too much overlap would be lack of penetration and in some circumstances another would be evaporation another would be drift if in windy conditions. You are better to have it slightly high rather than to low. to low will give you stripes.
 

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Discussion Starter · #9 ·
Thanks Nitro, and all. Stripes is right. I try not to spray in much wind anyway! Thanks all, I was thinking what could be bad about it, and seemed like a good idea, but wanted to run it by y'all.
 

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check tips are they 110 or 80 degree, often we see more trouble with the boom to high (more than 20 inch above target) resulting in drift no penetration . Most booms will not go lower then 20"
 

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I've dealt with some aussies who are spraying soil treatment in high stubble areas, who experience a lot of wasted chemical from the high stubble getting in the way, so there is no real overlap. The solution is generally to raise the boom and even if it means using an 80 degree tip to get a more 'steep' angle so the chemical doesn't necessarily get stopped by the sideways motion of the spray pattern.

Again, makes a big difference in how big the pigweed is before getting it sprayed. Just keep in mind that the spray will generally hit the 'terminal velocity' after so far after leaving the tip, so you want it to reach the point where it begins to slow down just a little above the weeds.
 

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I've dealt with some aussies who are spraying soil treatment in high stubble areas, who experience a lot of wasted chemical from the high stubble getting in the way, so there is no real overlap. The solution is generally to raise the boom and even if it means using an 80 degree tip to get a more 'steep' angle so the chemical doesn't necessarily get stopped by the sideways motion of the spray pattern.

Again, makes a big difference in how big the pigweed is before getting it sprayed. Just keep in mind that the spray will generally hit the 'terminal velocity' after so far after leaving the tip, so you want it to reach the point where it begins to slow down just a little above the weeds.
Just like a bullet starts to slow down immediately upon leaving the barrel, I would think that spray droplets would be the same. The moment they leave the nozzle, they start to slow as there is no longer a force behind them.
 

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Just like a bullet starts to slow down immediately upon leaving the barrel, I would think that spray droplets would be the same. The moment they leave the nozzle, they start to slow as there is no longer a force behind them.
Exactly right. I saw an article somewhere that had a little picture showing what these guys testing the speeds said.

I think it was something like with a 110 degree tip @ 60PSI, terminal velocity is at like 12-14" or something. Something tells me like 2/3 of the distance to the ground is picking up speed, and the last 1/3 of the distance is done with the spray slowing down to like 7KPH when the spray hit the ground.

I'm going to try and find that picture.
 

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Discussion Starter · #15 ·
Wilger, yeah, that is nasty stuff. And my pigweeds sure as heck got way out of control here while I was waiting to make arrangements with the seed guy for replant. But, the glyphosate is killing them, so not palmer ameranth.. ..yet. I wish I would have gotten them with my tips higher for a better kill, but they are going to see some steel too pretty soon.
 
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