rot on new growth (L. Purpurata var Carnea)

[greg_s]

Within the last few weeks the tip of the new growth on my L Purpurata var Carnea has been turning black. I took it to my local shop and they said that it was something fungal. They also said that it had to be cured systemically because the rotten bits were actually growing out of the new stalk. They sent me home with Phyton27 and told me to give it at least 2 good drenchings.

these pictures were taken right after my second treatment. Does anyone have any experience with either this kind of rot or the Phyton27? I have to admit that it looks worse from the first treatment to the second and it has me a bit nervous.

Also, the piece that is being damaged...is that the part that will become a leaf or is it the part that will become a bud sheath?

Any help/advice would be greatly appreciated.

Thanks,

Greg

[Daniel S. Barrett]

Hi, to answer your second question first, it's a new growth, for the plant to go to sheath, it has to be as mature as the growths next to it. You did the right thing in taking it to the shop for advice, they were right, it does look like a fungal problem, I'd use their advice & use the physan as recomended. You'll know it's been successful when the black disappears, & the affected part of the growth becomes a dried (to the touch) brown. When it grow out some, cut the dried brown tissue back 1/2" in to green healthy tissue & treat the cut with diluted physan on a Qtip. You might find it nessary to treat it a few more times to be completely successful, I keep a small spray bottle handy for such emergencys. Orchids don't do well in stagnant air & high humidity So, I'd suggest adding a fan in the growing area (if you don't already have one) to lightly keep the air moving. This will also help to keep bacteria & fungus from settling on your plants.

[greg_s]

Thanks very much for the advice Daniel. Do you have any suggestions about how often to spray it down with the Phyton27? I read the directions and it really focuses on amounts and not frequencies.

Thanks again,

Greg

[Cynthia, Prescott, AZ]

My preference would have been to cut the leaf off below the discoloration immediately. Cutting some of the outer bracs won't hurt anything. Use a sterilized cutter for any surgery and dust with sulfur or cinnamon. I like Phyton 27 for serious cases like this, but my experience is that Phyton 27 is on the expensive side for most people. I paid $53 for 8 oz. I hope you got a better deal than this. Definitely hang on to the stuff, and don't waste it on general fungal spotting. If you cut below where I see the damage in the picture, you will not really lose much of the leaf, as there is a lot of growing left to do.

I use the Phyton about once a week or a little longer, what ever is convenient. And since I have a lot of orchids and a lot of work keeping up after them, this dictates how often. I have no hard data on how often to do it. I have a few serious problems right now. They are at least a couple of months past their discovery time, and have now gotten 3 to 4 sprayings. They appear to have stabilized, so they probably wont get any more treatments. However, I spray thoroughly, I don't soak or drench, the material is just too expensive to use it liberally, and spraying seems to work.

As to why this happened, you may want to look at your culture. Weakened plants have these kinds of problems. Maybe not enough light, maybe too cool, or maybe shock from a chemical treatment the plant can't take. Well grown plants (the right conditions) don't get these serious problems, no matter how many spores are around.

[greg_s]

Cynthia,

Thanks very much for the advice. I actually got a really good deal on the Phyton 27 because the greenhouse sold it to me at cost (about $25). So far, I have only done the 2 treatments. I have been spraying the foliage and the medium until it begins to drain from the bottom. I am thinking that this would technically be a "drenching"? The part that makes me nervous is that it is continuing to get worse. I am not sure if the moisture from the spraying is just encouraging it or if I am just being impatient. Should I keep with my spraying or should I go straight for the cut?

Thanks very much!

Greg

[Cynthia, Prescott, AZ]

You need to do surgery and do it now. Use a sterilized tool, and be sure to give at least a 1/2 in clearence of good tissue where you cut, then spray the cut area if you have some of the Phyton made up. then dust with the cinnamon or sulfur. The cut edge will turn brown for an 1/8 inch or so, and that is no problem. But if you see one or two spots where the discoloration is clearly starting down the leaf again, cut a second time with more tissue as a buffer. Hopefully this wont happen. But, you must stop this from progressing, even if you loose the entire new growth. Keep us informed how this goes.

[greg_s]

Cynthia,

Again, thanks for the advice. I will perform the sergery when I get home tonight.

How should I go about sterilizing a tool to do the cutting? I have seen some people do it with a blowtorch but I do not own one. Would a candle/lighter produce enough heat to sterilize? or is there some other way I should do it (rubbing alcohol or something)?

Thanks,

Greg

[Cynthia, Prescott, AZ]

Don't use alcohol. Heat the blade until it is very much past the too hot to touch stage. Don't know if a candle would do it, but some of these propane lighters can put out a heck of a flame similar to a blow torch. Otherwise, soak the cutting tool in 10+% freshly made bleach solution, or a saturated solution of trisodium phosphate, not one of the substitutes, for about 20 minutes. Timing is not exact, but do it longer if you think the tool may not be particularly clean. Or, use a new unhandled razor blade.

[greg_s]

Sounds like picking up a fresh razor blade might be the easiest way to go. I'll give it a try and let you know how it goes. Thanks again!

Greg

[jerrymeola]

I have been warning about fungal rot all summer here in Florida and on this forum.

I would cut it off including the entire pseudobulb. It will not grow well and never flower so why take the risk of it spreading.

Spread of fungal rot is extremely fast. It can overtake the entire plant in less than a week. So that is the reason I take fast drastic action.

Prevention is the issue. Better air circulation is a big help. Watering at the base rather than on top will also help this species. The rot develops when water (rain in my case) gets in-between the leaves of the new growth and does not dry out fast enough.

Purpurata is also a species that likes its roots exposed. I no longer grow them in pots. They do excellent mounted.

Phystan 27 is a powerful fungicide. Be extremely careful with it. It is toxic to humans. It is systemic, it will entire your blood stream through your hands. It works best as a preventative in a commercial application. I do not recommend it for hobbyist. Weekly spraying during rainy season helps control the rot, but I have limited faith in its ability to stop rot once it starts. The rot grows faster than it is killed. Again cut it off.

[greg_s]

well, here it is post-sergery. I did not remove the new growth entirely, but I did cut it way back. I dabbed a little bit of the phyton 27 solution on it (since I had it made up anyway) and then sprinkled on some cinnamon.

How did I do?

Greg

[Cynthia, Prescott, AZ]

Looks good to me. Now just need to wait and see how it goes. I don't think you will need to spray with Phyton 27 again.

[Aniko]

Hi Greg, I crossed my fingers for the success of this surgery - I hope your patient will be fine!
Aniko.

[greg_s]

This morning I wake up and take a look at this one again and everything initially looks fine. Then, when the light catches it right, I notice that the outer layer looks fine but the inner layers have shrivled. I pinch a bit of the tip with between my fingernail and was able to pull out about a half inch of what looks like leaf going bad. Not black like before but brown and yellow at the base. Is this an indication that I didn't get it all? Should the entire bit of new growth go?

[Cynthia, Prescott, AZ]

Often times when a leaf has this kind of a problem, the rot travels down the leaf to the psuedobulb and ends there. If the section came out easily, it probably is repeating this pattern. I would wait a little longer to see if the problem continues into the new bulb, which it may not. You may want to cut the outer sheathing off further down to expose the good tissue of the bulb. Purpurata is monofoliate, so that was probably the entire and only leaf the new growth had, and now there is only a bulb inside the sheathing. But, the sheathing is living tissue, tho it will be short lived, so use a sterile tool again.