Some people have advocated using 20% acetic acid as a herbicide, for spot treatment. So it can be used on dandelions growing in the lawn, for instance. I suspect that standard commercial food grade 5% white vinegar, poured directly onto a dandelion, would also work. We have hard water here in Madison, caused by underground limestone beds, where our city water supply comes from. When watering blueberry shrubs, I use 6 fluid ounces(volume) of 5% white vinegar per 4 gallons of tap water. However, if I am trying to lower soil pH to fix a problem, I have used 12 fluid ounces of 5% white vinegar per 4 gallons of tap water, without harming the blueberry shrub. Bear in mind that vinegar is taken up as a food source by bacteria living in the soil, so the pH will rise over time as the vinegar disappears. Lowering soil pH with diluted sulfuric acid will keep the pH down for a longer period of time.

"ericwi"
Thanks for the info, but I did see your original post and was looking for more.
Please see the original post.
Quote "My concern. In other forums there are reports of some using it as a total herbicide? Should it be kept off the leaves when watering? Could I use Urea at the same time, if so what strength?
Any other special concerns to be noted?" End Quote
Please if you can answer these questions I would be grateful.

beeman: I can categorically state that my raspberry leaves did NOT like being wetted with water that I had adjusted down to pH 5.5 with vinegar, it burned them and the damage could have been worse. After overhead watering the raspberries with the acidified water I hosed them off with straight tap water thinking the 5.5 water maybe could be a problem. In the locations I did a very complete job of rinsing the leaves everything looks fine, in the spots I didn't rinse very well the leaves are anywhere from partially to completely burned and dead. Lesson learned the hard way. Too bad it won't kill the bindweed that easily!

'michael357'
I would suggest there was more to your problem than meets the eye.
Today I did some .pH testing using a calibrated .pH meter on the stuff I use.
My water from a rain butt tested at .pH 6.2 adding 4 fluid ozs of 5% vinegar reduced the .pH to .pH 3.1. I used the same set up to water my blueberries a few days ago and they look better already.
I then used the same setup on my rasps and straws early today without incident.
Just out of interest I tested my well water which we use everyday and that came in at .pH 5.6.
Next test is to use well water and vinegar, should be even lower!

I'm a little like Eric. My well water is very hard. I just pour some vinegar in a bucket and add some water. No real measurements. This is for blueberries. I've noticed the bigger plants seem to handle well water just fine, at least so far this year. Rainwater is a heck of a lot easier if you can collect some.

Its a lot slower, but you can mulch with oak leaves. I would still do something to treat the initial chlorosis/iron absorption problems and soil pH.

Where I have been dumping bagged oak leaves for several seasons, my pink hydrangeas have all changed to blue this year. Which is pretty unheard of here, our soils are just not acidic enough to grow a good blue hydrangea without artificially manipulating them. So, its definitely lowering the pH.

It should work the same for blueberries over time.

beeman: I'm glad you haven't had any leaf scorching from acidified water. My water is acidified with a 2 point calibrated pH meter bracketing pH 5.5, I am very familiar with pH meters having been a lab rat for many years so I'm confident that the water is really pH 5.5. As to wether or not it scorched the leaves, I have 3 reasons to believe it did. 1) the leaves that were by far burned the most were down near the bottom of the plants on the inside of the (very densely foliated) bed, they likely were not rinsed off thoroughly with the tap water after the acid water. 2) the portion of the bed at the end that didn't get the acidified water shows none of the scorched look. 3) all of the foliage (up high and along the edges) that I know was definitely rinsed off with tap water shows no sign of scorching.

I am stumped as to why a pH 5.5 water would cause scorching but am not ruling out the possibility that raspberry is susceptible to it. Acid rain, if memory serves me correctly, was not injurious to all crops and plant life in the north east back in the days when it was at it's peak, some plant life was particularly susceptible.

For the remainder of this year I'll either make damned sure all the leaves get rinsed with tap water or put the acidified water in with a watering wand down below the leaves. Next year, I'll try the whole process again and leave a small sacrificial area that doesn't get rinsed to see what happens to it sans rinse.

BTW, the scorching showed up within 48 hrs. of the application of acidified water, everything was fine and dandy prior to that. When I use straight Wal-mart vinegar as an herbicide, it pretty much produces the same results on some weeds.

"michael357" The Plot thickens!
As you can see from a previous post I only used 4 ozs of 5% vinegar and that dropped the .pH to 3.1. This I have since used both on my rasps and tomatoes without any scorching and that has been 48 hours ago.
As I said the plot thickens, what caused your scorching I don't know, but I do know my stuff is looking better already, so I will continue to use it for the time being on a weekly basis.

Beeman: yes indeed, the plot thickens. The temp. was about 95 deg when I hosed down the berries, don't remember if the sun was out or if it was approaching sun down.

I e-mailed a friend who was in Mass. doing some acid rain research long ago and he confirmed that it stripped many trees of their leaves but certainly not all plant life. No doubt, the time of exposure, pH and other environmental conditions play a roll in severity of damage caused by acidified water. Maybe I just got them all wrong at the same time and the plants paid the price.

It is all interesting none the less.

I know you didn't ask for this, but ....

How about avoiding the possibility of leaf damage by scratching agricultural sulfur into the soil?

Get a soil test (from a Soil Lab), tell them what you want to grow, ask how much sulfur to add, and how often to repeat the treatment.

It's a reliable method rather than the home gardener vinegar "fix" which is exceedingly temporary and has certain risks, as has been noted.

"jean001a"
I agree with your suggestions, sulfur is a better fix, regretfully it is slow, as it takes up to a year to see results. Not much good for this seasons plants, whereas vinegar has almost instant results on this years foliage.
I did note in the first post a readout of .pH from a soil test of 7.8.

I'm with Jean. I mix in soil sulfur to my potting mix when I plant my blueberries, but I also top dress with aluminum sulfate. I get quick results, as well as long lasting results and don't have to worry about burning leaves. I do this for my blueberries which I have in pots that are in a mix of 1/2 compost and 1/2 azalea/camellia potting mix. Our soil out here in S. California is just too alkaline to plant directly in the ground without major work, so planting my blueberries in large pots with special soil that I add about a cup of soil sulfur to, which works very well. It's too hot here in my part of S. California, even as close to the ocean as I am to water with acidified water. My blueberries are rich green and very, very happy :-)

Patty S.

Patty,

How long have your plants been in pots? And, are you adding more sulfur periodically?

thx.

RM

For anyone attempting to grow blueberries in an area with alkaline soils, there is a practical need to do your own pH testing. If there are shrubs scattered around the yard, the pH will have to be tested at each location, so using a soil testing lab is out of the question. Testing should be done twice a year, because the pH will slowly rise, due to the alkaline nature of the surrounding soil. To keep the cost of repeated pH testing down, I am now using bromocresol green dye indicator, which covers the range 3.8 to 5.4, appropriate for blueberry shrubs. There are several ways to lower soil pH, and drenching with diluted vinegar is quick and easy, since 5% white vinegar is readily available at the grocery store. Commercial blueberry growers use diluted sulfuric acid for this purpose. Agricultural sulfur is the least expensive method of lowering soil pH, but only if you purchase it in 50 pound bags at a farmers supply co-op, where fertilizer is sold in bulk. For anyone who is struggling with soil pH issues, I would advise to hang in there and keep trying, the results are worth it. Just remember that too much acid is lethal to plants. It helps to use a notebook and record test results, as well as applications of sulfur and/or diluted acid.

I have been trying to dial in what's going on with my water. I just moved to this house last September so this is my first year dealing with the water here which is from two seperate wells. I will at times see a huge shift with my well water in just a weeks time. If I use a low pH mix of vinegar today, check the pH tomorrow and it will be 5-5.5. If I then water without vinegar for a week and check the same pot again, it will be 6.5 or higher. Of course everyone is different depending on high alkaline or how acid your water is. I am using a cheap poke in the dirt meter that I clean after each use with a bit of brillow pad but it seems to be consistent. I am starting to think that I will need to adjust my water for every watering.

About aluminum sulfate, anyone else using this product? I did a search on this forum and found where Fruitnut had some problems with it in 2009 dropping the pH too low. I like the fact that it drops the pH immediately unlike sulfur which can take up to a year.

RM

Hi Jean: I'm using the acetic acid in the irrigation water to deal with high bicarbonates in it, the transitory soil pH drop is just an added bonus. Spose I could use sulfuric acid to handle the bicarbonates and get a less transitory added bonus of the S in sulfuric acid but I've lost my desire to handle haz. mats. at this point in life. some days it feels like I'm pushing a rope with this strongly calcareous soil, even though the pH is 7.2 some plants come up short on Fe, especially maples as well as the fruit trees during the Spring flush of growth.

To others: Ammonium sulfate is a suitable source of N and S if one has the dual objective of lowering soil pH and adding N, it is found in a crystaline, water soluble form. Of course, it takes time for the sulfate to be converted to sulfuric acid in the soil which then drops the pH.

micheal: I could be wrong but think the acidifying effect of ammonium sulfate is immediate. The sulfate won't be converted to sulfuric acid but doesn't need to in order to lower pH. If a real chemist thinks otherwise, let me know.

I've found chelated iron effective against spring chlorosis. But it is best applied to the soil before symptoms show.

Fruitnut: My understanding of soil chemistry has oxidized a bit over the years but, I believe going from NH3 to NO3 involves the loss of a H+ molecule; in other words, a soil acidifying reaction occurs, same thing happens going from NH4 to NH3 to NO3, a H+ is lost at each step. Therefore, if nothing else, ammonium sulfate fert. will aide in dropping pH via the N conversion to NO3. I'll defer to the chemists on the sulfate but believe the same thing occurs there too over time given the proper soil environment. You may well be correct, the SO4 never goes to H2SO4, ok chemists, chime in and bail me out, please.

Ditto on the chelated iron provided the correct chelator is used for one's given soil, I.E. EDTA doesn't work well at all in calcareous soils like mine. One of these years I'll try that route when I get the desire to buy the smallest quantity I can get which will still likely be a lifetime supply.

BTW, I presume you are aware of the above and am writing it for the benefit of others.

OK. I give in my head is starting to ache.
All I wanted was to discuss vinegar treatment, which I think has been swamped.
Thanks to all who contributed, good information.