# Gallons per acre for effective broadleaf control



## Edd in KY (Jul 16, 2009)

I am setting up a new ( to me) 20 ft boom sprayer for pastures and grass hay fields. When I calibrated it at 20psi, and a reasonable spraying ground speed, it was putting out 11 gallons per acre. This is great for minimizing refills and with fan jets it should get decent coverage. But what have you learned in your experience? I will be using Grazon Next HL on pastures and Crossbow on Hay, both with surfactants. Will 11 gallons get the needed leaf coverage? I am using 20psi to minimize drift.


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## Vol (Jul 5, 2009)

Edd, I used to use 20-25 gallons per acre, but changed to 10 gallons per acre when I noticed on most herbicide labels that their minimum gpa for application was 10 gallons. I cannot tell any difference on the effectiveness of the herbicides I used doing both gpa's. For pastures and hayfields you should not have any problem. 30 psi and under is recommended for low drift requirements.....20 seems a little low but a good indicator of your coverage is by observing the effectiveness of your coverage when using glyphosate. The resulting coverage will be very obvious.

Regards, Mike


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## rjmoses (Apr 4, 2010)

I run 20 gpa at 40 PSI and 5.5MPH.

Drift is a function of droplet size, spray height and wind. A smaller droplet size will give better coverage at the risk of more drift.

Some weeds require the herbicide to spread more over the leaf surface to be effective. Adding MSO, non-ionic surfactant or ammonium sulfate is always a good idea unless contra-indicated.

Hope this helps....

Ralph


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## swall01 (Jun 10, 2018)

I use the TeeJet brand nozzles and have different sets for different applications. You need to stay within the PSI range for the nozzles you have. 20 PSI is not reccomended on the chart for any of the tips i use even though the data (gpm) is published for them. I would suggest 30 PSI as minimum and 40 PSI as ideal for most applications without getting into a droplet size that is too small. If your grass is more than about 10 inches deep you will likely not touch any weeds or insects at ground level with 20 PSI. The weeds that have just sprouted are just as important to kill as those above the grass canopy. Also, some dont realize worm defense is to fall to the ground when threat (tractor vibration) is percieved. So either way you want enough pressure to punch all the way through.


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