Black rot on emerging Cattleya pseudobulb

[sand_tiger86]

A while back, I posted about this very same issue with the very same Catt. The first growth had black rot that started at the leaf tip as the leaf began to peak through the sheath (still a very young growth with only the tip of the leaf emerging). I ended up having to cut the whole growth off because it just kept spreading lower through the emerging leaf as it grew. It then started to put out two new growths, and one of them looks okay (for now) but the main one it put out is having an identical problem. Black rot that only starts at the tip of the new leaf. I have yet to see what the other new growth will be like, because the leaf tip has not emerged just yet. I haven't let water stand in them, and have a fan on at all times, as well as them being outside in pretty hot conditions, so I'm not sure what's causing this to happen. I guess I'll have to cut this one off as well, but in the meantime (since I caught it earlier than last time) I've been using alcohol and antifungal daily in hopes the it may cease the spread and I'll be able to salvage it. Has anyone else has this issue? It just seems to happen for no good reason. Maybe it's just a bad egg and it'd be best to throw it out?

[tucker85]

It happens to me every summer. I try to spray with dithane 45 and thiomyl every month but I still lose a psuedobulb here and there. Cattleyas are the worst and certain cattleyas seem to be more susceptible than others.

[leafmite]

I read that it might be a calcium problem. I am using crushed oyster shell now and all the new growths look good. I have a few older growths that survived because of the isopropyl alcohol treatments. I know how frustrating this is. It attacked the new growths of my seedling catts, spread to other growths and I lost many of my catts and a few others. I started treating with alcohol a little too late.
Good luck!
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[sand_tiger86]

Interesting...I wonder what Calcium would have to do with black rot, though?

[cdayinflorida]

As Jeff noted: dithane 45 and thiomyl...but I add in Banrot and Cleary's 3336. I spray once a week on rotation. Many people will bulk at the ides of spending money on fungicides and try using cinnamon and other concoctions. If you have ever seen blackrot run through a collection it is worth the investment.

[Dazed]

I have read some about the whole calcium thing and I think there is some merit to it. I was having a similar problem with an oncidium and calcium or magnesium deficiency was mentioned. I crushed some egg shells and put it in the mix and gave it a dose of epsom salts. That was a few months ago and so far I haven't seen it come back. Never hurts to try it I guess.

[poetiscariot]

Calcium is actually pretty chemically active; I wouldn't be too surprised if it makes an environment that's inhospitable to molds. I had recurring root rot problems a while ago, but I just stepped my watering down a bit and it sounds like you've got that under control. Epsom salts are a magnesium compound, and my understanding is that that's why they're effective for a lot of gardening problems -- not so much that plants need magnesium, but that fungi can't tolerate it.

[BValdes]

Hey Kelly same thing its been happening to a couple of my Catts I noticed it last week due to all the rain we've been having here in FL first thing I did take them out of my Gazebo and put them in my screen porch so no more rain and check with my local orchid supplier here and besides doing surgery to the rot part he prescribed (Dithane M-45 & Thiomyl) 2 tea spoons of each in a galon of water and apply via spray once a week for three weeks and after once a month basically same treatment that Tucker and Cathy have mentioned above, lets hope I got it in time.
My supplier did mention something to see if the black started at the ends or tips of the growth and run down then it could be a deficiency like (Calcium) but if it started at the crown, roots or bottom of the growth and come up then it would be a lot more serous like black rot.

[sand_tiger86]

Well, I don't want to speak too soon but my alochol/fungicide treatment seems to be working. The black crap seems to have halted, and the new portion that's growing it is healthy and green. Maybe I caught it just early enough! I suppose when it grows out enough, I'll just snip the black tip off?