Combatting brown rot


#101

Commercial growers around here did fine with captan controlling brown rot before these better materials were introduced- but they would respray after every heavy rain and I’m not sure how often they sprayed it when it didn’t. Before my orchard was supplying me with all the local fruit I need I would sometimes buy peaches from local orchards with captan still visible on the fruit. Yum. At least it washes off, but it is sticky.

Protectants require overkill in a way, if that’s all you are using, because you can’t afford the BR to start.


#102

Most IPM programs suggest just that. MFF and Indar have the same mode of action, so i would not use both of them. The Brown rot could adapt to that method of attack. I would use one of them with Bonide’s Fruit Tree and Plant Guard, as it is the only consumer option for Pyraclostrobin and Boscalid, which use a different mode of action against brown rot. It’s like if this were a battle, you would have forces on the eastern, and western fronts both coming in to attack the enemy. .
Another example of mode of action is one may rip proteins off the cell wall destroying the fungal cell, whereas the other enters the cell and shuts down the mitochondria from making sugar to feed the cell. Pyraclostrobin and Boscalid, are just as good, and maybe even better against brown rot than MFF. So I use both, and have zero brown rot in my orchard. Plant Guard contains an insecticide too, some object to that, I find it useful as when I spray for brown rot I spray for PC too. So I like it a lot. Lambda-cyhalothrin the insecticide has been extremely effective against PC for me. Although the product must stay cool. Heat breaks it down. I buy it in the winter from Amazon.


#103

I actually rotate between captan and topsin m mixed together, that is what I do the majority of my sprays with, then every few times I use either indar or pristine, so far this has been very effective


#104

I didn’t know that about the heat

I like the Bonide mix for prune plums, that always seem to get PC later than PC is supposed to be


#105

The thing is that if you have a hundred acres of a single species literally touching branches the math tells me that the odds of developing resistance are a hundred fold over a few trees in a mixed species home orchard. I don’t worry too much about resistance in this setting. Likely if and when resistance finally develops a replacement will have been invented.

On the other hand, if there are commercial orchards nearby, resistance may become a very real issue, but it will not be of your making.


#106

I’m wallowing in misery as I watch my entire peach crop be wiped out by brown rot. I’ve tried some last-minute sprays but apparently its just too late.

As someone who knows almost nothing about the biology of brown rot but has seen the effectiveness of bleach on lots of other types of fungus, I am wondering if anyone has ever tried a bleach solution on brown rot? My guess would be that I’m certainly not the first one to think of that, but I didn’t see anything on google searches about it. I also suppose there could be some health concerns, but I wouldn’t think a diluted solutuion of bleach would be dangerous once it dries since most of it would evaporate.

Anyway, does anyone know if there is any evidence of success or even any tests done with spraying bleach solution onto peaches to kill the brown rot spores?


#107

Why bleach? There are very effective fungicides. Get what is designed for the job.

I saw the weather data you posted recently. 80s day, 60s night, and rain every day. That’s ideal weather for BR. You need the best fungicide you can get not a household disinfectant.


#108

Even the readily available Immunox treats BR.

Mike


#109

Not very effectively. Cornell only recommends myclo for blossom blight. Monterrey Fungus Fighter at highest legal rate may prove useful- it is more specific to BR and has kick-back. I’ve stopped BR in its tracks after rot had started with the similar SI, Indar. Dried it up.


#110

@alan

Kevin sounded like he was on an emergency situation and I figured that Immunox was the most easily available emergency measure and better than bleach :grinning:

Mike


#111

Two inexpensive fungicides are topsin m and captan. They are what I use most of the time.


#112

The reason I was looking for something as odd as bleach was that I’ve tried Immunox and it didn’t seem to help much and @mamuang said it didn’t work for her either. Now, to be fair I fully admit that the reason Immunox didn’t help was almost certainly because I applied it for the first time when my peaches were just a few days from ripening and undoubted had already sustained massive exposure to BR. I wouldn’t be looking so far “outside the box” if I had done the right thing and started using a fungicide from the start. But this is the first year I got hit by BR and I never sprayed for it in prior years either. Don’t get me wrong, I didn’t really think I was clever enough to come up with some innovative, ground shaking new tool against BR that researches and experts had never thought of. But I’m desperate, other things didn’t work (due to late application after exposure I’m sure) so I just thought I’d ask. Over the weekend I was using bleach to kill and remove the fungus from the north side of my house’s siding, and it worked so incredibly well that it just made me wonder if it might do the same thing on peaches. Also, there was the chance that bleach could be the kind of thing that the professionals and commercial folks and others wouldn’t recommend because of some hazards related to applying it, but if it would save my peaches I was willing to give it a try. That is why I threw it out there. I knew it was a long shot but there is always the chance someone would say “oh yea, it works great but no one talks about it because it would be an off label product/application.” If that had been the case I’d like to have known it and may well have used it (much to the objection of those like yourself who would never do anything not labeled/approved…but I’d have like to have the chance to make that decision for myself. That is why I asked the question and why I was wondering if Bleach might be an option. Sounds like its not, so now I know.


#113

When trees are small and young, brown rot often isn’t a factor in orchards around here. People then tend to assume that this will continue being the case until it isn’t, or at least I did. Once it is in your orchard it tends to continue to be a problem except on exceptionally dry years. The sterol inhibitor class of fungicide are the only form with kickback, I believe. On sites that sound like yours I usually get by with one or two apps of Indar about a month before fruit ripens. Actually the two apps are mostly to take care of earlier and later fruit, but the later fruit gets the early spray as well. Early peaches get only one- every year. I use Indar and Pristine, but the active ingredient in Monterrey Fungus Fighter is supposed to be nearly as good. Of course, home use formulations sometimes reduce legal highest rates of concentration- which totally sucks.

I should mention that I also use Indar in my second insecticide app about 2 weeks after petal fall, but have been successful without doing this.


#114

THank-you Alan. That was an especially helpful post. You also answered another question I had, which was whether I was looking at several additional rounds of spraying to apply Indar (or whatever I use) or whether I can just mix it in with one or more of my applications of insecticide (Imidan 70 WP in my case). Sounds like I can mix the two and spray together, right? Thanks.


#115

Yes, of course. Most pesticides are compatible. The only ones I use that are problematic are oil and captan.


#116

I used that homeowner formulation of Pristine with insecticide this year, and my cherries were both rot and PC-free. If this carries over to the other stone fruit later in the year, I’ll be very pleased.

Of course, beginning in June, we had abnormally hot and dry weather. Still is promising


#117

I’m mixing up some calcium chloride for some pluots on a branch that is morning shaded…last year they rotted bad so we’ll see if it makes any difference.

There is some research that backs up this method…

The problem is how much to mix and how often.


#118

I bought some a few years ago when I saw this or a similar study. It sat gathering dust but I finally remembered to start adding it this year. I also want it for my apples to prevent bitter pit (I don’t get much of it but occasionally I do). I should totally hammer brown rot this year, along with calcium I am using Indar and Regalia plus occasional sulphur and Serenade.

It could be that a combo of Regalia, calcium and alternating sulphur with Serenade could give a non-synthetic nail to brown rot, maybe I will try it sometime.


#119

Just a word of caution on fungicides gleaned from the scientific literature and not subject to widespread field studies: YMMV!

I am sure that an application of methionine - riboflavin and a relatively low dose of soluble copper (60 mg/L) caused significant fruit surface damage to some of my apples. I also tried it on peaches for BR and shot hole. But I think it magnified some leaf drop problems on my Redhaven tree. (After already heavy leaf drop from PLC.)


#120

Scott and @warmwxrules,
Do you have particular brand you bought or I can just buy calcium chloride crystal, ice melter?