Questions not deserving of a whole thread


I find the university of California IPM site useful for that. Check the link below for Brown Rot; it lists various fungicides and their class/mode of action.


Thanks, that’s useful

Most of what I have here is Group 3 mode


Thanks very much for that bit of information, Tippy it was very helpful as always. I honestly just can’t ever be sure if a particular problem is being caused by OFM ir PC. I’m 100% sure that I have both since I’ve seen adult versions of each, but I have just an awful time telling them apart. I’ve looked at all the photos and gone through all the supposed tests (does it crawl or roll around (ie legs or not), does it have brown on its head, crescent shaped scar, and so on) but I still have a hard time being sure which is which.

BTW…in your post you mentioned CM (Codling Moth). I don’t have much problem with them on peaches. They do get in my apples but I find them to be easier to deal with by spraying than OFM is. If I spray Apples on a reasonable schedule, I can pretty much control them. With OFM I get at least a little damage no matter how often I spray, and if I wait just a few days too long or it rains a lot between sprays, they can devastate me . In that post you also mentioned CP…I assume this was just a typo and you meant PC, is that true or is there some other pest called CP?

@Olpea Can you (or anyone) please give me some idea of how much vinegar (or some other readily available acidifier) I should ad per gallon of water to make it sufficiently acidic to work well with Imidan?). I am already reading that some acidifing agent should be used but not once have I seen reference to an amount. I honestly don’t know if I should add a cup of vinegar or a teaspoon full. Even an educated guess from you would be very helpful. I’d also like to hear if you recommend things other than vinegar, but as I said, I’d like to use something I can find locally. I’ve even seen folks here (Drew) suggest battery acid but aside from being hard to find, it doesn’t seem like something I’d want to mess with. Seems like lemon juice might work, but that’s just a guess. What say you? Thanks, Mark


On a scale, I’d say the risk of developing resistance in your backyard goes:

Fireblight (with streptomycin) > rots > scab/rust > insects.

My general thinking there is that bacteria tend to develop resistance to synthetics quickly because of fast growth rates and more rolls of the genetic dice. Next would be rots, as they are active for longer periods, then scabs and rusts which have a defined, yearly lifecycle. Finally the risk is lowest for insects as the rolls of the genetic dice are lower than micro-organisms like fungi.


Thank you so much for that, Rick! I’m also impressed that you were wise enough to notice that I shouldn’t have used 5 pounds of Imidan in 1.5 growing seasons on 125 trees. I mix in the strength the label says, but do spray a little more often and I also end up wasting a pretty good amount while trying to be sure I get full coverage-more than just to the “drip point”, I spray the whole tree first, then I start from the bottom up making sure I get contact on the BOTTOM of all the leaves. I also spray the trunks and a few inches around it on the ground hoping it might at least deter peach tree borers. Anyway, the point is I know I use more than most. HOWEVER, your estimate is more accurate than either of us knew…just this past weekend I was pleasantly surprised to find one of those self-dissolving, 1 pound bags of Imidan that I had put in a cabinet in my garage and completely forgot about. So between my excessive use and the fact that I still had 20% of my 5 pound bag means you were dead-on with your statement! Pretty neat.

I don’t want to start a whole rabbit trail here, but do you mind if I asked you what you use to fight brown rot? Thank-you.


That’s because we all have different water sources, mine is from Detroit via the Great Lakes. So all have different amounts of carbonates and difference in pH. So it would be hard to tell you, without testing your water. I use 1 tablespoon of vinegar and my water tests at 5 pH. I use battery acid for blueberries or other acid loving plants only. Not for sprays. I use sulfuric acid for plants because it permanently eliminates calcium ions by binding them into gypsum (gypsum stays nuetral). Vinegar, or citric acid, would break down with time from bacteria, and release the calcium and once again raising the soil pH. So I would have to add more and more to my water as the soil pH would long term increase.(as the water I’m adding is very basic, only acidic for a couple weeks till the vinegar breaks down).
The current commercial/industrial pH strips I’m using only measure 4.0 to 7.0 so can’t tell you what exact pH of my tap water is? Last time I checked with other strips it was 8.2. I would use vinegar in just about everything, captan won’t work at all if not in acidic water. Also most insecticides, half life is increased if used in acidic water. I rarely use vinegar because I use rainwater for sprays. Mine is about 5.1 to 6.0.


Good eyes. Yes, I meant PC (plum curculio). Not sure what I was thinking ( or not!!). I have PC and OFM bad every year.



I use citric acid as an acidifying agent. Most commercial growers use it because it’s cheap. Food grade citric acid is available in 50 lb. bags, from chemical suppliers.

For a backyard grower, it’s also available in some grocery stores. Even if you can’t find it in grocery stores, it’s easily available on online in places like Ebay, Amazon.

As Drew mentions, I would not use strong acids like battery/sulfuric acid for sprays. Those kinds of strong acids can have unpredictable effects on the foliage.

In terms of rate, it does depend on the pH you start with and the buffer strength of the water, so it can differ.

However, I get, and appreciate, your question, that you want a ball park. I can tell you I’ve measured my water carefully, multiple times and can say that one teaspoon of citric acid per 16 gallons of water will lower the pH of my water to 5.9. One teaspoon per 24 gallons of water will bring the water to a neutral pH (7.0)

I’ve read general guidelines for farmers to acidify water. They ask the very same questions you are. Here is one from MSU. They posit that two ounces of citric acid per 100 gal of water will lower pH from 8.3 to 5.4.

Interestingly, the rate I use of one teaspoon per 16 gal of water to produce a pH of 5.9, equates to roughly one ounce per 100 gal of water. It figures to a small handful per 400 gal. tank of water, lol.

Seriously though, these numbers should give you at least a ballpark of how to acidify your water. Incidentally citric acid is a much stronger acidifying agent by weight than vinegar.


also more delicious on homemade boozy gummy bears :crazy_face:


Yes, it does appear that way! You can buy it in the canning section, vinegar is cheaper though. They rob you in the canning section!
Nice builtin about pH thanks for posting that. It really illustrates how much pH matters, also has many products I use. Like Malathion. If I used rain water I would get at least 8 days protection, but if I used tap i would get 19 hours!! pH 6 = 8 days; pH 7 = 3 days; pH 8 = 19 hrs; pH 9 = 5 hrs

It’s not a bad idea to have reliable pH strips and figure out how much you need. You just need to write it down. Doubtful you need to test water more than once a season. You can get very relaible pH strips (plastic not paper) here. I like the 4.0-7.0 strips. Expensive, but these are very accurate. A box lasts years.


That Citric acid sounds stronger than the 33% Sulfuric that I use. Brady


I have not found anything that works as well as Imidan at Petal Fall on Apples or Peaches. The product label concerns me, so I only use it once per year at Petal Fall and I wear a full face respirator.

Indar works well on Brown Rot in my area. Good sanitation is also important - be sure to remove old leaves and prunings. I rake everything from around the trees into the row middles and mow it several times.

Its pretty hard to guestimate how much Imidan is required for each tree. I use 3# per acre on both Apples and Peaches. Three pounds covers 800 apples trees but only 125 peach trees.

I understand what you said about the cost of chemicals. The cost can get out of control quickly.

You have a lot of trees which should translate into a lot of fruit at some point. Have you considered selling any of it? Perhaps at a Farmer’s Market or directly from the farm? You can net the farm loss against your other income which will help with the chemical cost. It’s also helpful when you need to buy farm equipment to make the work easier.



That’s one of the reasons I’ve never used Imidan. As I recall the cost is close to $50/acre, which compares unfavorably (cost wise) to something like generic Warrior, which costs $2.75/acre (Although I know you can’t use pyrethroids because of your apple trees.)

Imidan has it’s limitations here because stink bug is such a problem and moves into the orchard about the same time as PC. Imidan doesn’t have much control for stinkers, but I hear it’s a cracker jack on PC.

Drew, I just read that article. Although the lady is a plant pathologist, she’s not a fruit tree specialist and she’s just passing on info. she’s read. From the article I can tell she has little experience with real life application of her knowledge toward fruit. Notice she advises dipping pruning tools in antiseptic between each pruning cut. While that may be an ideal, practically it’s unnecessary. Commercial growers all over the world not only don’t disinfect between cuts, but not even between trees with no adverse effects (a few commercial growers might disinfect for fireblight, but the article refers to brown rot).

Although disease organisms can build resistance to compounds faster, it’s still not necessary to rotate fungicides every spray to avoid resistance for the home orchardist. Even single mode fungicides take years to develop resistance, and that spraying millions of acres repeatedly. Resistance isn’t going to happen on a 10-20 tree backyard orchard, unless the pathogen introduced was already resistant to start with.


Yes, but we have the same problem as with vinegar, a least for blueberries, the acid will breakdown with time. It will keep long enough to work as a spray though.

Well that’s good to know too. Although I’m surprised even cancer is spread by instruments in surgery. And it’s a huge cell compared to bacteria or fungal spores. If you must disinfect a quick and easy way is to spray tools with Lysol spray disinfectant. I must admit I have never done it. I do hear experts saying you should. I just heard it the other day on a garden podcast. Also saw it on grafting videos this week too.

I do also sort of disagree with you about resistance. I think you’re greatly underestimating the ability for fungi and bacteria to adapt, and I am an expert when it comes to these organisms. At least human pathogens, it isn’t mass use that brings on resistance, it’s improper use by as little as one person in the use of antibiotics. It only happens in one person, and a resistant strain is born, I guess because you’re treating so many cells in an orchard it is more likely to occur, but occurs on one tree, not a mass conversion of all the cells. So all you need is one tree for it to happen. I would agree odds are low it will, the more trees the higher the odds it will occur. So I think you are correct, but some risk of resistance. And considering home growers are amateurs they are more likely to say not acidify their sprays weakening them and giving the organism a chance to adapt to the weakened spray. That should greatly increase odds of resistance. Most of my expertise with these organisms concerns isolation, growing them, and identification of human pathogens. I used to grow HIV and TB, now I grow plums and peaches. TB is so cool looking in cultures, it looks like a mushroom. Not in shape, but appearance. It looks nothing like other bacteria. It is beautiful to me. Sparrow hospital in Lansing when i worked there had 800 different strains. One of the best labs in the country.


Well, we are closer to agreeing. I would say while it’s possible for a backyard grower to develop a resistant strain, the odds are so remote so as not to merit any worry over it. I definitely wouldn’t advise a new backyard grower to go out and buy different classes of fungicides so he/she could avoid developing a resistant strain.

Also you should know that commercial growers can be plenty sloppy with pesticide resistance too. I know a guy with an 80 acre orchard and he sprayed nothing but Proaxis every season all season long for insect control. I know another guy who just sprayed Imidan for insect control. He had over 100 acres of apples/peaches. I don’t know what fungicides they used, but my guess would be they handled it the same way (That is, find something which works and stick with it.)

I’m not endorsing that policy, just saying it happens.



I understand what you mean about high pesticide cost.

I’m still learning how to grow apples and peaches and since I just grow a few acres I’m more focused on using stuff I know will work and safety rather than the cost per acre. My primary concern over Imidan is more about safety than price.


@blueberrythrill and @Olpea I’ll not drag you through another one of my long winded posts, so just let me tell you both that your posts above in response to my original question and follow up were both incredibly helpful- as usual. Thank you very much for taking the time to share your wisdom and experience with this inexperienced grower. Thank you both!


What are good beneficial insect and/or hummingbird attractor plants? I’ve got a lot of chives from my mostly-useless try at planting a pest repelling border to my berry bed, and a fair amount of space where all the lavender and marigolds died. The internet is full of info, but I’d prefer advice from experience.

I’d prefer perennials.


Bees love cilantro flowers. Cilantro bolts easily in the summer heat. I let them be because their flowers attract a lot of bees. Never have to plant them again, they reseed heavily.

Also cardinal flowers supposed to attract humming birds. I’ve never seen them around my cardinal flowers though.


I have cilantro popping up everywhere, even in the middle of my lawn! I’ve always loved the smell and taste, unfortunately my wife does not so most of my cilantro goes to waste. My daughter and i did make a lovely salsa with the cilantro, fresh tomatos, and some chives. Very good, but maybe a little too sweet. My daughter isn’t much into hot spicy foods, so no peppers to cut the sweet.