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greentoe357

what are these leaf tissue depressions?

greentoe357
9 years ago

I gave some cuttings I received recently an alcohol spray, then a shower, then an overnight soap water soak (6.5 tbsp of Dr. Bronner's unscented soap per gal), and then another thorough shower before planting them in the mix. Four days later, I noticed leaf tissue sort of collapse and get depressed / thinned out in many spots, often over the whole leaf surface, on some of those cuttings. The damaged parts of leaves feel very dry and sandpapery in some cases, wilty in others, always very thin and different in color.

Here is how this looks. Hoya aldrichii (the color change from healthy green to sickly bronze/copper color is also visible):

Lacunosa 'Splash':

Macrophylla (the depression / thinning out of the tissue is particularly visible here):

Macrophylla variegated (not only the lead damage visible in the lower part of the pic, but even the petiole thinned out in the middle):

Mindorensis has different damage on a few leaves. The spots are also depressed / thinned-out, but they are brown and less spread-out over the surface of the leaves:

Other species affected are australis 'Mrs G' and macgillivrayi.

I've done undiluted rubbing alcohol sprays and soap baths before, and there were never any damage. But there were some differences this time:

1) the soap soaks were never such long ones, previously an hour or two at most, I think;

2) the soap baths and alcohol sprays were never done consecutively - only one at a time before.

What do you think happened here and what should I do differently as prophylactic/treatment of pests for incoming cuttings? Those damaged leaves are goners, I understand - but what can I do to stop the damage? I think it's happening very fast - just 4 days have passed. The last few days were a bit cold, so half-way through these 4 rooting days I put them on top of a heating pad. It may not be necessary any more now. Humidity has also increased a bit, at 40% now, which I think is about the lowest I'd want it for rooting - otherwise I can enclose them all into a humidity container. Should I cut off all the affected leaves, or let them fall off on their own? Any advice is appreciated!

Comments (12)

  • greedygh0st
    9 years ago
    last modified: 9 years ago

    Aw. You must be feeling so devastated looking at that damage. I'm sorry.

    I've had the exact same experience before, but I'm not sure what all the relevant variables are, because, as in your scenario, I'd done components of the treatment previously without incident.

    The first time it happened to me, it was with an Aleya order, and I had created a crazy bath with VF-11, vodka, a little soap… and left them in it for a few hours. Such a dramatic transformation in such a short time. It has also happened to me on another occasion with just soapy R/O water, but a longer than average soak.

    So, here are my very rough conclusions:

    1. Be careful what you add to the water.
    2. Don't soak the cuttings for longer than they need.

    Helpful, huh?

    I think when cuttings are stressed, they are more vulnerable to reacting badly. I don't really know what is going on on a physiological level, but I'd like to. It does seem like sometimes they'd be better off with a shorter soak and then placed in a high humidity environment, rather than being submerged for too long.

    To me your soap dosage seems quite strong. I don't use an exact measurement, but I just give my tub a squirt - it can't be more than 1/2-1 tsp per gallon - just enough to suds up the water. When I use a hand mister, I just put a drop or two in per liter and I do see results. I know you were following commonly prescribed 1T/liter scale, but I'd be curious to hear what dosages other people around here typically use. It seems to me that, given the way it works on the insect, people are overestimating how much is required.

    At least one person I know of has reported using Dr. Bronners on Hoyas without problems, but I have always been too scared to use it since Mike reported experiencing a bad reaction from the surfactants used in a natural soap he tried. I stick with the favored original formula Palmolive now.

    As you say it might have been the one-two punch of alcohol, then soapy water. You'll note that my Aleya cuttings failure also involved those two components.

    I'm sorry I can't be more helpful - just know you aren't alone.

    As far as going forward, go ahead and trim off all of the leaves that are in very bad condition, and leave those that seem like they still have a shot. It is my experience that more leaves than you expect will end up dying off, and I like to trim the goners off just to get them out of the way of the leaves that are still functional. Plus, you're about to put the cuttings in a humid environment so we don't want a bunch of dead matter on them.

    It is going to be a fight to get the cuttings rooted now, so put on your nurse's outfit and roll up your sleeves. What happened with my cuttings is the majority just ended up dropping all their leaves and shriveling up before they even got close to rooting. Some, however, pulled through. You are probably going to have a much better success ratio than I did, since your cuttings don't have the kind of travel stress mine did, and most of them look like they are nice succulent species that still have a lot of fight left in them. I would absolutely put them in high humidity. Make sure the leaves don't lean up against a wet surface and don't let the humidity get too too high. This is a good time to root in your grow stones.

  • vermonthoyas
    9 years ago
    last modified: 9 years ago

    I think it is possible to go a little overboard on these prophylactic measures on new cuttings. I look mine over well and rinse them off, and sometimes I don't even do that. As far as hitting them with an alcohol spray after soaking that is overkill. I still think that all of your cuttings will still root and be fine. You will eventually be able to cut off the damaged leaves and know one will be the wiser.

  • greentoe357
    Original Author
    9 years ago
    last modified: 9 years ago

    Thanks, GG and Doug. I also posted essentially the same post here (https://www.facebook.com/groups/214525878704580/314169012073599/?notif_t=group_comment#!/groups/214525878704580/permalink/314169012073599/), and there is a rather active conversation happening there as well.

    > So, here are my very rough conclusions:
    > 1. Be careful what you add to the water.
    > 2. Don't soak the cuttings for longer than they need.
    > Helpful, huh?

    Hehe. I can appreciate some comedy in the middle of a tragedy. And I get it that there are no exact recipes.

    > I don't really know what is going on on a physiological level, but I'd like to.

    Yeah, me too! Carol Noel asked me if she could send those pics to a pathologist friend of hers. I'll gladly share what her friend says about this, so we all can learn.

    > To me your soap dosage seems quite strong.

    I took it from here: http://www.ext.colostate.edu/pubs/insect/05547.html. I knew that many people use lower concentrations, but many of those same people are very imprecise. The university source and the more precise dosage won me over. Although it's SOAP, not some fancy chemical, so approximate dosage may be ok, of course.

    Meanwhile, I cut off all the affected leaves or leaf parts and will keep watching and hope for the best.

  • greentoe357
    Original Author
    9 years ago
    last modified: 9 years ago

    CN said this:
    "I talked to the plant pathologist at the University Extension Service here in Hilo - quite a bright fellow and explained what happened. He said it is the soap which was taken in thru the stomates into the interior tissue of the leaf and did what soap is supposed to do: broke down cellular tension/integrity = mush. My suspicion is that soaking them in the solution is what did them in. Whenever I have used a soapy solution to wash leaves it has been an in/out dunk certainly no longer than a minute or two and then a rinse off. I have only done this with H. compacta to get rid of the mealybugs inside the curled leaves and it did the trick. "

    Lesson learned. Hopefully it'll help some of you reading this before you make the mistake as well. WEAK soap, SHORT soaks!

  • greedygh0st
    9 years ago
    last modified: 9 years ago

    Thanks for sharing that explanation. It's quite scary to see what soap can do once it's absorbed into the body of a plant.

    I agree with your "weak soap short soaks" summary. It doesn't take that long for soap to do what it needs to do to the bugs as long as it makes direct contact. So there is no need to expose the plants to more of it than necessary.

    I guess the reason I felt the way I did about using the lowest effective concentration of soap is because that's the way I treat my own skin. We know soap is an enemy to human skin. It strips away the natural barrier of fatty acids, which keep skin moisturized and help prevent infection. There is also some research that shows that it interferes with our skin's ability to absorb vitamin D from sunlight. And it decimates populations of good microbes along with the bad ones. There have been studies that showed that these good microbe populations are correlated with lower levels of inflammation on minor everyday injuries. So, they are probably just as important to our skin as they are to our digestive system.

    Now, I'm embarrassed to say I don't know enough about the composition of a leaf to know how all this impacts them, but I think there's every reason to err on the side of caution. Especially after what you've learned, I'm going to be even more judicious about when I use soap.

    Of course that's not to say that it is more harsh than other insect preventatives. Who knows what negative impact systemics or neem oil or alcohol might have too. Keeping our plants strong and healthy in the first place is always going to be preferable to any invasive treatments - same as with us.

  • greentoe357
    Original Author
    9 years ago
    last modified: 9 years ago

    Re soap dosage, I saw very vague advice. People in articles and forums were saying things like "a few drops into your spray bottle", or my favorite, "a bit of soap into your spraying water" which seems utterly imprecise and so so useless. The research article I linked above seemed serious enough to trust, so I went with that dosage. Apparently, that was a mistake (or maybe overnighting the soak was, or both - I might need to re-read the article after this). If anyone has good references to soap dosages and times to soak plants, I am all ears. The soap I use is not a detergent, not scented, "gentle", and was recommended by some orchid growers I know: http://www.drbronner.com/DBMS/category/BABYMILD.html.

    I personally am starting to look at soap as a DRUG - again, as evidenced by my experience. They don't tell you to "pop a few antibiotics pills when you can remember", and for very good reasons.

    Re "lowest effective dose" - sounds great, and if we could find that dose, even greater (the key word is "effective"). I am afraid it's just as easy to slip into "homeopathy" territory and arrive at a placebo treatment that will not even rise to the effectiveness level of placebo, because the bugs that may still be there did not get the memo, like human patients do.

  • pirate_girl
    9 years ago
    last modified: 9 years ago

    Maybe just don't soak it. A quick swish, swish & rinse & then just take it out.

  • greedygh0st
    9 years ago
    last modified: 9 years ago

    Well, I think the thing about soap is that you need enough to form that surfactant effect on the surface of the water, but it's not like a chemical which distributes evenly through the water and needs to be diluted to a specific level. That's why people's measurements are so vague.

    I do love Dr. Bronners - I use it myself in the shower and for home cleaning. But even the gentlest soap is still a mixed blessing.

    I agree with the conclusion that you can probably make it extra soapy, so long as you just leave it in there for a short time and then rinse it afterward.

    It's been interesting to hear how many people on FB take the "less is more" approach with cuttings. My experiences do bear out this thinking.

  • pirate_girl
    9 years ago
    last modified: 9 years ago

    Hi GG,

    "It's been interesting to hear how many people on FB take the "less is more" approach with cuttings. "

    I don't do Facebook, could you pls. elaborate a bit what you mean by the above? TIA

  • Denise
    9 years ago
    last modified: 9 years ago

    I'm with Doug. The maximum I do is swish my cuttings about in a sink of tepid water with just a squirt of dish washing soap. I've never used alcohol on fresh cuttings, and I never soak my cuttings, unless they are dehydrated, and if I soak, it's only in some plain water with a bit of SuperThrive in it. If your worry is about mealy bugs or scale, you should probably just understand that sooner or later (if it hasn't happened yet), you will get them. Anyone with a large plant collection learns to deal with them because we do not live in sterile environments. I remember years ago, I bought some bananas at the grocery store and a couple days later, I went to eat one and on the flat end, there was a little cluster of mealy bugs!

    I find the best defense to bugs is my eyeballs (though it DOES get harder to see them as I get older, LOL!) When I water my plants, I also spray them with VF-11, and in the process of that, I lift vines to spray under leaves and look for buggers. Looking at your plants regularly is important, and if you find a bug, treat the plant. And then look closely at the plants that were close to it.

    I wouldn't expose a new cutting to anything that I didn't absolutely have to...

    Denise in Omaha

  • Denise
    9 years ago
    last modified: 9 years ago

    I meant to make one other comment... Several years ago, I read an article about the "toxic" things we use everyday without hesitation. It suggested that the increase in cancer is due to our "need to be clean." Soap, shampoo, antiperspirants/deodorants, hairspray, air fresheners - all of these things are polluting our bodies and our environment. We are literally poisoning ourselves, because our skin absorbs these things. But, as the article said, no one would ever advocate going back to the days when you took a bath once a month, and everyone walked around smelling like a barnyard.

    This comes to mind only because our plants, like us, absorb what we put on them. Just as I wouldn't soak in a tub of soapy water, I wouldn't do that to my plants. Wash and rinse, just like you would your body. Swish-swish!

    Denise in Omaha

  • greentoe357
    Original Author
    9 years ago
    last modified: 9 years ago

    Thanks, you guys, for commenting. I just looked at the cuts again, and the damage seems to have stopped at the cut leaves, except for 6 or so lacunosa 'Splash' leaves dropped. We'll see what happens.

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