Some formulations more than others, in my experience. Captan Gold 80 doesn’t leave much, even at full strength for me.
Hmm, I’m not used the specific Adama forumulation. I do use an 80% active ingredient vs. a 50% formulation more commonly sold.
Maybe I’ll give Captan Gold 80 a try.
You can try it out with a small bag- not too much investment.
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I guess its just crazy to me that people do not know what ph they are spraying these chemicals at and i also assumed in whatever pesticide registration class or whatever you took they would have taught you about ORP and potential hydrogen.
Maybe pesticides that require specific ph should come pre mixed or you should go to your chemical supplier for refills. Its hard for me to find a chemical they dont want you spraying with reverse osmosis water or distilled also and i feel very few people do that on here. Maybe you should have to pass a questionaire before you go spray these things into peoples backyards OR maybe we are doing things the smartest and best way possible currently.
I’ve not ever seen that as a requirement on a label of any pesticide I’ve used. I’ve not even seen a label recommending that.
University fruit specialists sometimes even discuss the use of pond water as a source for spray water. With more water conditioning requirements of course.
Well Dow Syngenta and Bayer only test their products with reverse osmosis water and only make their effectiveness claims when you use that and surfactant they pair with it. This is a standard industry practice.
It would probably discourage you from buying more pesticides to tell you that.
I know a Bayer scientist in charge of their of a team in pesticide development. They used to have a test farm about 5 miles from my house. We talked quite a lot about testing and registrations of pesticides, since it was both an interest of his and mine.
Of course when testing scientists are going to try to isolate as many variables as they can. Otherwise test results are meaningless. But that has no bearing on the expectation of how it’s used in the field.
All these companies know that no farmer is going to use reverse osmosis water or distilled water for a spray solution.
There would have to be an enormous conspiracy for all these companies, their sales force, along with the EPA, to sell products to 2 million farmers farming hundreds of millions of acres producing all the food for our nation, secretly keeping from everyone that we should all be using distilled or reverse osmosis water in our spray tanks.
This line of discussion is going in the direction which is more or less fruitless for me, so I will politely and respectfully remove myself from it.
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Great im glad you agree they use RO water when testing these chemicals and like these chemical companies i honestly do not care about the applicator.
What i do care about is pesticides mixed with regular water supplies are likely to be less effective (thinking calcium carbonate here) and possibly some of the compounds in the water will make the pesticides not degrade at the same rate. As well as the ph of the water you spray has a huge influence on almost all these chemicals and spraying with the correct ph is important in keeping disease low.
A ph meter is a tool i would think everyone spraying chemicals would have similar to PPEs
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I spent yesterday afternoon in a recertification class for my pesticide applicators license where water PH and pesticide effectiveness was discussed. My well water is slightly acid and I don’t mix the chemicals until I get ready to apply them so I don’t have a problem. It’s my understanding that the water PH only effects the half life of the chemical before it gets sprayed, so if Captan has a half life of 8 hours at a PH of 7 and it gets sprayed in 2 hours, it does not deteriorate more once it reaches the tree.
No mention of distilled or RO water in the spray tank but using pond water was discouraged for many reasons.
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I ran field studies doing testing of agrichemicals for many years. Lived all over the country testing various different chemicals in all sorts of crops. Apples in Michigan, corn in Illinois, lettuce in Florida, rice in Arkansas and Louisiana. I was responsible for calibrating sprayers and witnessing (and sampling) the mixes of whatever chemical we were studying. These were tests the chemical manufacturers needed to do for their chemical re-registrations. No applicator that I worked with ever used anything but well water. I was there, watched it myself.
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Hello There,
I am an OP. I posted this thread because I’ve found the info to be helpful for peach growers, commercial and backyard.
I hope people are considerate and stay on topic. Please refrain from creating a controversial issue (i.e. organic vs non organic or the like) that could side-rail the thread or result in the thread being closed. Thank you.
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The problem with Captan is the label makes no mention of the fact it is pH sensitive. It would be nice if the information was on the label. It’s not like I don’t know what a base catalyst is or what hydrolysis is… I do.
I suspect the reason it omits this information is Captan is a very old fungicide and the label was originally approved in era when it was not considered necessary to include that information. Just as drugs at one time just had to prove that they were safe but did not have to prove that they were effective. Plus manufacturers are hesitant to change labels since a revision has to go thru an approval process. A similar situation can occur with drugs.
Captan is available for home use and is not a restricted fungicide so why would you expect your average home owner to know there is a need for pH adjustment if it doesn’t say so on the label? I wouldn’t expect that. That would be like me expecting your average man off the street to know what a silanol, a silane ,or a silazane is which I don’t.
ORP is not a very common test why would you expect a home owner or a licensed chemical applicator to know anything about it? It’s not very useful unless you’re trying to qualify certain waste streams and if you aren’t doing this you don’t need to know anything about it. People make pH adjustments without ORP data all the time.
As far as using distilled or reverse osmosis this is standard laboratory practice for any kind of lab scale testing or evaluation. So the initial testing on a lab scale would of used distilled or reverse osmosis water. That maybe is where you got the idea that all testing is done with this type of water. But as testing is scaled up or moved to the field you’re going to switch to cheaper water sources that are more representative of real world conditions, again this is standard practice. Also don’t assume the Syngenta and Bayer do all of their testing. There are companies that specialize in running trials for fungicide/insecticide residue.
You seem to like to question the competency of people that are well…competent.
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The testing continues long after a pesticide is licensed and Cornell recs are often partially based on field observations and not controlled studies. Once a pesticide is out in use on thousands of acres practical lessons are learned. Agriculture isn’t run by as stringent rules as medicine so the fruit gurus are happy to share the experiences of commercial growers if they find out, for example, that myclobutanil isn’t all that effective for brown rot control on stone fruit and that fabuconazole (Indar) works a whole lot better. However, the myclo label still states that it helps control brown rot and you can’t tell just by reading their labels that one is much, much better than the other- you have to dig deeper.
One thing I feel sure of all the experts I’ve gone to for advice, whether they worked for my chemical supplier or Cornell, is that their primary concern is for the growers to get good results and that it be within IPM standards.
Thank you for chiming in here and this will be my last statement on ro and distilled water.
Does calcium carbonate or other minerals and contaminants commonly found in potable water increase or decrease effectiveness of pesticides or fungicides?
Honestly I would like to just get to best practices as I believe that could help us use less pesticides and fungicides per year.
@mroot I was trying to explain why one person who has 9.4ph water and uses say a tablespoon to reduce 25 gallons to 6.0 is not applicable to then say another person with 7.4ph water could not say they should only use half a teaspoon.
I felt ORP high = more ph adjuster needed and ORP low = less ph adjuster needed was a good simplified way to explain why there is not a formula on ph adjusters to use x per gallon to drop to 6.0.
Many times a person with a real high or low ph has an extremely low ORP and will need minuscule amounts of ph adjusters to jump where as people in the stable zone 6.5 to 7.5 usually have a very high ORP related to hardness and require more ph adjustment to move at all.
This is why ph meters or drops are so important.
I won’t worry about even adding into the conversation on ph and sprays as you guys seem to feel that labels are infallible and yet incorrect all at the same time. What I will say is the ph matters for most everything you spray on plants
I’m not sure if this has been talked about,but is there a designated pH that should be a goal,when using Captan,or is it anything under 7?
I’m using it for the first time this year and have some battery acid,that is for Blueberry irrigation.A small amount,maybe a teaspoon was added to a gallon of tap water.The acidity wasn’t measured,so hopefully it’s okay.
For Captan a pH of 5 is considered ideal and gives a half life of 32hrs. At a pH of 7 the half life is 8hrs. You want to measure the pH and adjust it if needed before adding the Captan. See the links in the post below for more details. For backyard use a range of 5-7 would be acceptable in most cases since you will spray right after mixing. It is possible to adjust the pH to be too low which can damage plant tissue. See the links in the post below for more details.
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If you’re small backyard grower, just use rain water.
I’ll offer a few more suggestions, as we seem to be back to discussing practical application. As mroot points out 5 is a good goal for Captan. I actually shoot for 6 pH because, as Rick points out, once the product dries, it no longer degrades from hydrolysis.
I’ve not used battery acid (sulfuric acid) to acidify water, but I imagine it would be fine. I would not use muratic (hydrochloric acid) as the foliage probably wouldn’t like all the extra chlorine. It probably goes without saying that strong acids like sulfuric and hydrochloric are dangerous to handle and wouldn’t take nearly as much to alter the pH.
As I mentioned earlier, everyone will have a different results with the amount of acid needed to reduce the pH. I previously used the term alkalinity, which is easy to confuse with alkaline, but alkalinity (aka buffering capacity) is the ability of the water to refused to be acidified. It has nothing to do with pH (or potential hydrogen).
Until one gets a baseline on their water, it’s best to either use test strips or a pH meter, if you want to be exact. If you use a pH meter, make sure the bulb doesn’t dry out, which can alter the accuracy. I also bought some test packets with verified pH values to make sure my meter was calibrated correctly.
One doesn’t need to be that OCD about it though. University extension specialists have general recommendations for adding citric acid without ever testing the water or spray solution. That’s because the foliage of most the temperate fruits grown commercially here are fairly forgiving of acidified water. I’ve “eyeballed” the citric acid I add to the tank before, and added extra to make sure I have enough in the tank. I’ve never seen any negative effect on the foliage. As long as you aren’t using something like Copper (which should never be acidified) it would take some pretty acidified water to hurt the foliage or fruit. You can google the recommendations for the amount of citric acid per hundred gallons of water. Just remember, if using vinegar, it’s going to take about 24 times as much vinegar as citric acid measured by volume.
Most pest control chemicals are not affected by calcium carbonate (i.e. dissolved limestone). It will bind some herbicides rendering them less effective. Most people add AMS (ammonium sulfate) to the water before adding a herbicide like glyphosate to bind up the cations before the glyphosate is added. This year I’m using a Helena product called Request in place of AMS. But this issue really isn’t a consideration, unless you are using herbicides.
If one enjoys reading about the effects of water quality on pesticide performance, here is a pretty good slideshow presentation from Purdue. I scanned it. It looks pretty good. It discusses even the use of pond water and well water as a spray carriers (i.e. water used in the spray tank).
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I like to use rainwater for as much as possible. I use a lot of water! It helps a lot.
It does both. Depends what you are using.
On this forum pH to use for pesticides has been well covered since inception and before that we covered it on Garden Web. Links to best pH for each major pesticide are posted in this forum. I lost most of my links when I switched computers, I know I posted at least three sites on specific pesticides and best pH for them.
One reason I can think of best pH is not mentioned is because the label is seen as the law. So if you’re not using the suggested pH you would be breaking the law. I guess stating use at all pH’s is allowed would solve that. It does point out how careful with wording you have to be on these labels.
I think it’s a good idea, but I don’t write the labels.
