Hi folks. Yesterday I stopped by my local ag extension agents office for something else, but we started talking fruit trees. I was telling him about my battle with peach Brown Rot. He happened to know the University of Tennessee professor who is the peach guru and he just called him up, put him on speaker phone, and we all 3 chatted for 15-20 minutes. Basically, he said (and it is just 1 man’s opinion) that for my location, the best way to fight brown rot (aside from removing old fruits and cuttings, dead wood, etc) that he recommended the following in order of effectiveness and likelihood of success (so this is an "either/or list in case I can’t find the first 1 or 2 things recommended.
In a way, he said Indar has long been considered best, but that there is growing research that it is becoming less and less effective. So, he was a little ambiguous about whether Indar’s waning effectiveness made it no longer the best thing, or whether the other things he listed should be preferred in order AFTER indar. Either way, these are things he recommended and was quite strong on: I copied the part in parenthesis from each product’s web site.
Luna Sensation ( Luna Sensation is a unique combination of the active ingredient fluopyram, a novel chemical within the ‘SDHI’ family, and trifloxystrobin)
Merivon (Merivon is a pre-mix fungicide containing two systemic active ingredients: fluxapyroxad (succinate dehydrogenase inhibitors or SDHI, FRAC group 7) and pyraclostrobin (quinone outside inhibitors or QoI or strobilurins, FRAC Group 11).
Gem ( Trifloxystrobin. Gem™ is a broad spectrum fungicide for the control of certain diseases in almonds, citrus, pistachios, potatoes, rice, root vegetables (except radishes), stone fruit, sugar beets, and tree nuts. Gem™ works by interfering with respiration in plant pathogenic fungi. Gem™ is a potent inhibitor of spore germination and mycelial growth.
ALso, for all the above he was pretty strong in saying that captan should be mixed with each and all of the things listed above. He sort of explained why but I didn’t quite follow.
I’d really like to hear what you all think. I also want you to know that he was far from the academic know-it-all type. He admited that a lot of this was based on research done by other people and universities and that several colleges in southeast had formed a committee and put together these things. He also readily admitted that not everyone agrees and lots of people and professions have different favorites or at least different orders of preference for these.
Anyway, I’d love to hear your thoughts. I should also add that all of these are available at my local co-op in pints, but holy cow are they expensive (maybe not on a per gallon basis, but pints are from $270-$375. but for this discussion I’d like to hear thoughts on effectiveness more than value/cost.
I’ve heard some good things about these relatively new fungicides. I pretty much agree with the professor’s comments. Indar is still considered powerful, but these new compounds are supposed to be improvements in places where Indar has met some resistance.
I haven’t tried any of these because they are so expensive. I know you didn’t want to talk cost, but in my experience Indar mixed with Captan prevents most brown rot, even when the weather never dries, and is much cheaper.
In general mixing fungicides of different modes of action, increases effectiveness, which is why that appears to be the new trend for ag chemical manufacturers. One could think of it like this, if a person ingested a good quantity of arsenic, there’s a fair chance the person would die. But if the someone ingested a good quantity of arsenic plus strychnine, it would most certainly cause death. Hence the added (and sometimes synergistic) power of poisons with different modes of action.
The problem with some of these premixes is that the chemical companies charge significantly for the service of mixing the fungicides. They also preserve the effectiveness of their pre-mixes by reducing resistance buildup (which interestingly also adds to their long term bottom line). From my perspective, I don’t need to pay a premium for someone to premix.
Adding Captan adds another kick to the fungicide because unlike most ingredients of pre-mixes in which the two active ingredients of the pre-mix have a single mode of action each, some compounds like captan, chlorothalonil, etc. have multi site activity, which further increases lethality and lessens resistance.
Just thought I’d point out that 5 peach trees sprayed with Indar and Captan will probably take decades longer for the Indar part of it to become ineffective than at a commercial site with sometimes hundreds of acres in a peach monoculture.
There is no research on the relative math of resistance development I’m aware of because just about ALL the research is about commercial production and everything the university gurus know is based on research pertaining to commercial production.
My hunch, which is supported by quite a bit of anecdotal observation, is that home orchardists don’t really have to be that concerned about their little orchards developing resistance problems. You can probably wait for the patents to run out before using newer formulas than Indar.
I hope your right and Immunox and Indar will continue to work in my small orchard for many years to come. The risk of resistance should be much lower than in a commercial orchard.
But I am still worried about resistance. I purchased stock from three nurseries this year and from one nursery last year. I have no way to check if any of that stock is contaminated with resistant strains of fungi. It wouldn’t be something I could visibly see. I doubt most of the nurseries I deal with have the means to test if the resistant strains are present in their nurseries either. So I take precautions and tank mix with Captan as well as alternate FRAC codes as much as I can. But I can see why people would want to look at Elevate and Luna Sensation to give them more options to keep resistance at bay.
Tippy, try the product below; I rotate it with Infuse and I believe it has different mode of action fungicides. One of its two fungicides is pyraclostrobin, which is common with the secondl product that Kevin mentioned in his original post.
I honestly forgot about this myself. Never ended up trying any of those but I’ve had good control of brown rot the last few years. Some places suggest captan isn’t very good for brown rot, but I just saw a University of TN professor on a local PBS gardening show saying it is one of the best things for brown rot!! So who knows. I alternate Captan and Myclobutinyl and pretty much have ended my brown rot problems. But that’s just me.
I didn’t see the Lunar Sensation split offer either. Also, I’ve never even seen the pricing. But what I’m doing is working, so right now I have no reason to change. But before I cracked the code I’ve certainly seen entire trees full of peaches destroyed in just a few days from brown rot. So to everyone, I say BR is nothing to mess around with. Many of our enemies will do some damage but still leave us with at least some fruit with perhaps some problems, but BR can destroy every peach on a tree. What hurts (in my experience) is that you really don’t know you have a big Brown Rot problem until right when the peaches start to ripen. By then you’ve put months of work into the fruit, only to see it all go bad in a few days. ;(
Resistance would likely only develop on fruit so it is very unlikely it would happen in a nursery which would probably only use captan as a fungicide if they used one anyway. Are you purchasing 1-year trees or something larger bare root? So many things to worry about when growing fruit. I think it is helpful to prioritize based on relative risk.
All my trees are standard bareroot trees or benchgrafts or trees I grafted myself. The largest would be like a Cummins nursery grade 1 tree.
There is fungicide resistance on lettuce so I don’t think you need fruit to be present to have resistance develop on fruit trees. It looks like any time you have a large population of fungus being exposed to a single mechanism of action fungicide you have a risk of developing resistance. If you expose the fungus to low levels of the fungicide either thru low rates or poor spray coverage the risk goes up.
A nursery is really a farm only it raises trees as a crop instead of fruit. So for fungicides cost per acre or cost per acre for a certain level of effectiveness probably drives choices in buying fungicides as much as anything else. Oplea posted about costs per acre here.
It looks like single MOA fungicides are cheaper than Captan at least in some cases. So I would expect nurseries to use them to lower their costs.
The nurseries are not isolated either. Budwood and rootstocks come into the nurseries from the outside. Now some nurseries probably grow all of their own budwood but few grow their own rootstocks. The rootstock producers are large specialized nurseries themselves and they need to spray their crops as cheaply as possible. In many cases you will have large numbers of small trees planted at high densities which are being sprayed with single MOA fungicides and I think resistance developing there is a distinct possibility.
Now in practice I don’t know how high the risk is and I don’t know what steps the nurseries are taking to prevent resistance from occurring. I also don’t know if they have a testing program looking at resistance in their fields. I know many nurseries have programs to prevent latent viruses from getting into their stocks but for fungicide resistant fungus I have no idea.
I used to think of my small orchard in an area where apples are not grown commercially as being rather isolated. And that coupled with the small size of my orchard shielded me to a large degree. But I am starting to realize that I am connected to the nurseries and rootstock growers and that means I am not as well protected from the issue as I would like.
You ask an interesting question about buying trees that arrive with certain diseases
I understand that some strains of fireblight have developed resistance to Strep in the northeast so I expect it’s possible for some trees or rootstocks sold by these nurseries to have the Strep resistant FB version when you receive them. Strep lost it’s effectiveness against FB in the PNW a long time ago and they use other chemicals to manage it. Lots of large rootstock nurseries are located in the PNW but I have no idea if importing FB bacteria that is resistant to Strep from that area is possible.
Don’t believe that importing Brown Rot on purchased peach trees is a concern but there is lot of discussion about the importance of rotating MOA to help reduce resistance buildup at every grower meeting that I attend.
I believe the current label for Indar allows for up to 8 applications as long as the maximum amount applied does not exceed a certain amount. 8 applications is lot!
Unfortunately like Olpea posted the newer chemicals are a lot more expensive than the old ones especially the ones with multiple MOA like Luna Sensation, Merivon or Pristine. Fortunately many are labeled for lots of fruit crops which makes it easier to justify the high cost of buying another expensive jug. Also, I noticed that most of the DMI fungicides (MOA 3) chemicals are listed with a threat of resistance - even the newer ones.
Nothing beats Merivon for bitter rot on Apples in my climate. The high price of this fungicide is not a problem for Apples and Bitter Rot, since it is so effective and nothing else seems to work as well. It also has the advantage of not leaving a white residue on the Apples like Captan.
I have not found it necessary to use Merivon on Peaches since Indar is so effective in my climate and very reasonable price wise. Been using Indar for over 12 years and no resistance to Brown Rot so far.