I think you got lucky if it was undiluted 50â isopropyl. Seems to me I remember using alcohol in high school to extract the red/orange/yellow pigment from autumn leaves, idea being that the alcohol acted as a solvent breaking down cell wall tissue and releasing the pigment. Now let me say that this was a long time ago (probably 1984), so I very well may be remembering this wrong....maybe it was acetone or some other solvent.
In any case alcohol is a solvent albeit a weak one and has a drying/dessicating effect, so I would certainly be weary of it's use as a fungicide. I have however read of it's use in diluted form as a fungicide. I usually only come across these type of snake oil recipes when reading about some organic potion that will never work.

BTW...I too use alcohol on my shears, but if you're interested in a organic (I think it's considered organic) fungicide/miticide why not micronized sulfur? Long term it is way cheaper than even dish washing liquid, and unlike dish soap it will actually work very well and also has some insecticidal properties. I don't know of ANYTHING that treats mildews as well as sulfur...organic or otherwise.

There was another thread here which discussed alcohol (isopropol) as a pruning shear disinfectant. The point made there (by myself and others) is that alcohol is not a particularly good disinfectant, it is a good solvent.

That is why it is used to wipe skin prior to a shot. It doesn't kill the bacteria but loosens them and allows them to be wiped away. The amount of contact time for alcohol to kill many bacteria is quite long; you aren't going to do much just by a quick dip or spray on the cutters.

A soak in hydrogen peroxide would likely be much better at killing disease organisms. Although even that probably would need 20secs or so of contact to do it.

A diluted solution (1:3) is frequently recommended as a topical treatment for soft bodied pests such as aphids, mealybugs, even spider mites on houseplants. It can be applied with a hand sprayer on a frequent basis, without rinsing....no damage. Isopropyl is typically found as 70%.

I'd be cautious about using it outside in direct sun on deciduous plants without doing a leaf test first. (Spray and inspect after 24 hours.) I'm not so sure that I'd use it for powdery mildew.

As far as powdery mildew goes, if the spores haven't infiltrated into the cells of the plant, then plain water can wash them off. Neem oil has both preventive and curative qualities. Summer oils work great to prevent infection.

Hi Rhizo. I'm a little confused about what is considered a summer oil. It is my understanding that these oils can be applied year round. The one oil that I already have is Neem. Is this considered a summer oil and can it be applied year round? Thanks, and welcome to Alabama. Not a bama fan. Thanks

Many accomplished grafters just about brag at how easy and simple their 100% successful grafting is done, almost implying that they can use a broken chunk of bottle glass and a strip of old dried-up duct tape to successfully graft a pc. of unidentified driftwood to a tall palm tree on the oceanfront beach. And it produces tasty, beautiful fruit the next year.....I am the opposite. I take lots of steps, materials, etc. to attempt every graft. One of those is to systematically spray 91% alcohol on bark, fingers, tools...whatever comes in contact with the cut scion and rootstock. It does damage new, tender leaves if any overspray hits them. As the wet bark of the r/s twig/branch dries up, I start the cutting/shaving/slicing on it. I wipe the pruner and knife blades while they are dripping wet using facial tissue to clean off sap, dirt, pathogens, etc. The sweet sap is like glue and it gathers all kinds of bark particles, etc and gets them stuck to the pruner and knife blades.

Alcohols are excellent cleaning agents but poor disinfectants (except methanol, it will kill many microbes). I suspect your spray simply washed a good deal of the spores off; but I bet the hyphae are still present.

Champs, by summer oil, I mean one of the highly refined petroleum oils. They have a much broader temperature range than the usual oils. Neem oil is categorized as a horticultural oil, but more narrowly as a biopesticide. Its use year round is limited by sun and heat so be sure to read the label....as with any oil.

I moved to Alabama about 13 years ago, but thanks for the welcome. Couldn't care less about either team. :-)

Why is it that people are always trying to find "home remedies" for issues that call for something more? Don't get me wrong, sometimes homebrewed things work quite well and are effective for certain things. Sadly, this is not the case with insecticides and fungicides when dealing with fruit trees. Sorry...it just isn't. I've tried any and all that have any reasonable science to them, and while it's true that some have "some" efficacy...they are in short, mostly ineffective wastes of time. Thing is, often times these products create a situation where more environmental harm is done with this stuff than would be if a more effective and correct product was used. Things like milk, garlic, chamomile tea, dish soap...blasting aphids with water and on and on...complete rubbish. Yes..I know, some of you have used them and seen some results...so have I, but it's minimal at best and you really have to strive to see those results. Sad reality is folks...they either don't work at all or their effectiveness is so limited as to make their results nearly negligible. I don't like that either...it's just the way it is. Sulfur is by far your best bet if organic control is what your after...in fact; it's the only one that makes environmental and financial sense and that's to say nothing of your time. Sulfur is devastating to nearly all non-engrained fungus like mildews...it will ERADICATE it..not just make a 5% improvement and it will have some staying power. It's cheap and has a low embodied energy content and it's been around and been used for this purpose as far back as history is recorded. They had alcohol then too, but guess what....they used sulfur. They did this because it worked. I guess if you have one tree in a pot on your deck or balcony, maybe, just maybe using some of this stuff may work if you like to fool with it everyday. Again...in the real world it's rubbish...don't waste your time and money chasing a pipe dream like I did.

I prune fruit trees all day about 6 and a half months of workdays a year and I don't generally use a disinfectant- even when cutting out fire blight strikes. When I actually see some research that shows it is worth the time I will change my practice. I just try to cut beyond any infected wood.

The one situation I would consider it worth the time is when fire blight has passed into big wood on a tree. In thousands of trees I've managed, this is the only situation where I've seen a return of fire blight on a subsequent year after removing diseased wood.

When I remove black knot from plums, I spray the wounds with chlorothalinal, work over a tarp to take away infected wood, but I don't disinfect my tools between cuts. I sometimes use three different tools when removing black knot and constantly disinfecting my shears, knife and pruning saw after each use would be highly time consuming. It is not practically possible to remove black knot without cutting into infected wood.

Of course, just because I do a lot of pruning doesn't mean I'm not a hack as a tree surgeon. You could argue that I over emphasize speed. If you have some research to reinforce that argument I'd be grateful for the education.

Appleseed: Would you take time to type out how you use sulfur in your fruit world? Thanks...On April 25th I completed a 6-graft topworking of a Wilson paw paw tree that itself was topworked 5 years ago. SMALL fruit. The 6 preferred-variety scions were cleft grafted after having soaked up Super Thrive in 3/4" deep water in a cup for a day after having been in a bag in the fridge for weeks, and got sprayed with a light coat of acrylic clear coat after the graft below was taped up. The clear coat is poisonous enough to kill pathogens big time, dries quickly before it can be absorbed through the super thin/tender paw paw scion skin, and seals in the internal moisture. The 91% alcohol was used on the tools, fingers, etc. to clean/sanitize. Five of the 6 scions grew out over time, and are growing very well, but one last scion remained dormant. It is pencil thick , 5-1/2" long, and has 2 good buds on it. A loose-fitting white plastic "tent" made from a strip of grocery bag sits on top of it to lessen the Sun blast, ward off flying bugs looking for a place to eat, ward off big birds looking for a perch, and ward off rodents here in squirrelsville as they crawl over almost every branch looking for something to eat. Even strips of tender bark. I have been peeking under the tent for many weeks looking to see if either bud would eventually bust out and start making a green shoot. On July 25th, I just noticed that one bud has a 1" long new shoot. After 90 days that have become very Sunny, dry, and mostly in the mid-nineties. For me, the occasional unexpected success makes the cheap, quick, simple extra steps worthwhile. ....On the other hand, the multitude of long-winded failure stories could potentially overwhelm the G/W server.

Copingwithclay...sure I'd be happy to type it out, but that's not what you meant is it? I'd also be happy to hear you describe what the super thrive does in your "fruitworld" since it's effectiveness has been debunked by a multitude of different groups. But hey...at $12 an ounce...why not?

Thanks Appleseed. I too am at war against bogus products supported by ringing anecdotal endorsements. Generally, if something really works in a way that would make growing fruit more profitable it is embraced by commercial growers who need every edge they can get. Because it is an international competition for market share BS mostly falls by the wayside. Different scene in residential landscape horticulture where products are pushed that only benefit the sellers and dreamers.

The sulfur use methodology and effectiveness in your fruit world could be helpful to those of us who are looking for a "better mouse trap" in dealing with some of the MANY foes in growing fruit at home. Anecdotal or not. Sincerely. It is what I meant. How do you apply it? When do you apply it? Where do you apply it? Details are informative. Thanks.

I was referring to the Superthrive not sulfur, BTW, I am a dirty grafter, though, and think the antiseptic approach is possibly based on research in the field of human medicine and the somewhat perilous logical leap of faith that it applies to plants in the same way, although their defense mechanisms have almost nothing in common with animals.

I would like to see the endorsers of careful sanitation do about 50 grafts- half sterile and half not, hopefully, with the same care in all other respects. I might do it, but I'm well on the Oscar side of the personality equation and feel this should be left to a Felix.

Clay...first, I wasn't referring to anything you did or were doing, but rather to the persistence among members to use less than effective methods based on homebrew recipes thought to be more environmentally sensitive. Allow me to state that there are FEW people more concerned about the environment than myself. Some might say I'm a clean energy guru, I drive a Prius, always recycle and am ALWAYS considering my every move and it's related impacts on our environment.
EVERYTHING we use has embodied energy and affects the environment. Dish soap for example...pollutants were released in it's raw material acquisition, manufacture and up until very recently nearly all contained phosphates...phosphates known around the world to be VERY serious pollutants...their impacts very long lived. Knowing these things we must consider a products effectiveness (or lack thereof) weighed against it's environmental impact.
I've tried nearly ALL these homebrew (supposedly "green" recipes and sadly they either don't work at all or barely work. I got sucked into this stuff a long time ago....just trying to save some others the hassle and eventual disappointment that is sure to follow. Harvestman stated his position very well and it is shared by me.
I'm certainly not trying to bust on anyone. If some homebrew recipe ever comes along that is effective, inexpensive and is better for the environment I'll be all over it. Until then careful application of the chemicals available while following manufacturer/gov't guidelines and only when needed is our best bet...both for success and the environment.
Sorry if I sound preachy and for getting somewhat off topic.

I think alcohol is great in the garden.

If you bring a bottle of wine and sit in the orchard, by the time you are done you just don't care about that fireblight etc

:)

" and think the antiseptic approach is possibly based on research in the field of human medicine and the somewhat perilous logical leap of faith that it applies to plants in the same way, although their defense mechanisms have almost nothing in common with animals."

Harvestman...I suspect you are spot on about this or at least mostly so. I too have always had a hunch this was the case.
I am sure however that viruses and bacterial infections could be spread by dirty pruners. I say this because I've seen open wounds in trees I've had become infected. We know the viruses etc exist because we can see them under high power magnification. We also know for a fact that these "bad guys" can be killed with disinfectants because we can see that too. There is an apple breeding video on YT (12 part Lubera in Switzerland / Germany) in which they describe how fireblight resistance is quantified. The trees are simply inoculated with the viral strain and then they see what the results are.
Videos and literature always prescribe pruning shear/tool disinfecting.
Having said all that, when watching production professionals pruning/grafting I rarely see them disinfecting their tools. My take on the whole thing is this: I think disinfecting pruners almost certainly lessens the likelihood of cross infection whether bacterial, fungal or viral, but in high speed production pruning it's benefits are probably not great enough to warrant the significant amount of extra time required to carry it out. Professionals (like yourself) have recognized this through a lot of experience and so dispense with this time consuming step.
I, like copingwithclay, also disinfect everything (hands, fingers, knife, shears, levering tools etc) and act as though I'm doing open heart surgery on a human in my every move. All the while in doing this though, I know I'm probably just wasting time. Thing is...it's time I have usually so I don't mind.
Like you, I too would like to see data on this and I have to think somebody somewhere probably have done such tests, but I've never seen or read anything about it.

Kippy I sometimes apply alcohol use in the orchard in this way too. :)
It's always effective when used in this manner..lol

FYI, I have a pruner, lopper and tree blade marked for fire blight use only. I still dip in rubbing alcohol when done, but that is more for my sanity than the trees health.