Does Roundup / glyphosate cause rust?

[beppington]

My friend showed me 2 containers of glyphosate-based weed killer he has, both of which mentioned "salt" ... something like "contains glyphosate such-&-such salt".

I don't see salt or sodium mentioned in my generic glyphosate concentrate, thank goodness.

But, I was wondering if the mention of salt in his 2 products would cause metal such as fence wire to rust? That would seem ridiculous to offer a weed killer that would rust your fence, but salt is salt, isn't it? ... with the capability to rust metal.

 

[MMagis]

Yes, it can. Though I can’t remember if it’s a salt issue or an acid issue. Either way, its primary reason for development wasn’t for fence rows, so I highly doubt they worried too much about it causing some light rusting. .

 

[beppington]

Would 2,4-D be a better choice then?

There are very fast-growing weeds & vines that envelope the new fence within about 2 months of the fence being done.

I certainly don't want to rust my brand new wire fence ... ~$250 for 200' rolls of it ... & I installed 3,400' of it But the labor is/was the real killer

 

[whistlepig]

I'm not saying it won't rust fence but I have been spraying fence lines with it for many years and haven't seen any damage from it. I put 2,000 feet of new fence 4 years ago and have sprayed it with out any noticeable damage.

 

[MMagis]

It sounds like 2,4D may work better for what you have, the vines in particular. How well it would work would depend on just what vine it is. Some are more resilient than others. I know it works very well on honeysuckle.
Most fence has a good galvanized coating on it, so realistically I don’t think gly will cause many issues. I’ve never noticed any rust, buy I don’t spray often.

 

[beppington]

Another reason I asked this question is that, after my friend showed me the mention of "salt" in his weed killers, I noticed a short ~150' stretch of new fence that I completed about 5 months ago & that became incredibly enveloped 2-3 months later, so I sprayed it with regular Roundup, & I'd say it looks a little less shiny than when it was new. I know the shine wears off eventually, but this seemed pretty fast, & I thought maybe the Roundup not only caused it but maybe it was well on its way to rusting.

 

[whistlepig]

I googled this and from what I am reading Roundup does rust fence although I have never noticed it. My wife won't let me use 2,4D around the animals so its either Roundup or the weed eater for me. I have 900' of fence along the road that gets coated with slush and salt from snow plows every winter and it still looks good. New fence looks shiny until all the oil washes off of it.

 

[DeeDubya]

Roundup eats up the brass sprayer nozzles and valves pretty quick. And I rinse them after each use. Being brass you wouldn't think. I've gone to using total plastic ones on my Hudsons now and they seem to last. :confused2:

 

[Pilot]

Salt doesn't mean table salt. To oversimplify, salts are classes of chemical compounds like acids and bases, etc. 2,4-D also has salt formulations, specifically, 2,4-D amine.

You are likely applying a couple ounces per gallon. Your fence is probably galvanized and rain should wash off any Roundup as it has to be highly soluble in water to be able to mix it with water. I wouldn't worry.

 

[whistlepig]

2, 4D only kills broad leaf plants. It does not kill grass. So the bottom of the fence would be covered in grass. I do know that fence that sits a long time covered with grass corrodes quickly.