Spraying hard water with Round-up

Asked October 21, 2020, 8:07 AM EDT

A test of my well water shows a hardness of 496 PPM. How much AMS would I need to use to spray Round-up on some phagmites I have trying to control ????
I invested considerable time and money trying to spray about thirty acres this summer only to discover my hard water messed me up.
Your help would be much appreciated.


5 Responses

Usually the recommendation for adding AMS for glyphosate applications is 17 pounds per 100 gallons of spray solution. If you want to email me with more details about your tank capacity and the exact product you're using I might be able to help you narrow it down a little better (hiller12@msu.edu).

I am using a mist sprayer, recently purchased, with a 65 gal tank. My rope wick applicator carries about 5.5 gallons. My third sprayer, conventional type carries 55 gallon.
I have declared war on phragmites covering about 45 acres. Any suggestions will be appreciated.

My inquiry of 10/23 has not had an answer. Your help would be much appreciated.

Based on your tanks that would mean you need to add the following AMS (assuming a full tank load is mixed). Note the AMS should be added to the water and agitated before the glyphosate is added.
65 gal tank- 11.05 lbs AMS
5.5. gal rope wick tank- 0.93 lbs AMS
55 gal conventional tank- 9.35 lbs AMS

All that being said, glyphosate applications to phragmites will not be effective if the plant is not actively growing (ie temps are above 50F consistently). So in most of Michigan, now is not the ideal time. The most effective timing is usually in August/early-September for herbaceous perennials as they are more effectively moving the herbicide to the root system along with the natural flow of carborhydrates to prepare for winter.

If you haven't already it might be helpful to contact your local CISMA (MI Cooperative Invasive Species Management Area) contact to see if they can offer any resources or guidance in your quest to eradicate your phragmites. You can check out who to contact at https://msugis.maps.arcgis.com/apps/MapJournal/index.html?appid=6b7f263e19a046d5b48da223bc4db99b

There is also "A Guide to the Control and Management of Invasive Phragmites" from the MI Dept of EGLE that may be useful if you haven't already seen it.

Thanks for your response. Very helpful. I did a considerable spray during Aug and Sept, so maybe I will see something next year, but knowing it would have worked better with the water spiked with AMS as outlined in your note.

Thanks again.