Help with fast moving fungus? on bellina leaf
 

Last night I noticed a translucent stretch on the edge of my bellina's leaf. Today both sides of the leaf are affected by whatever it is. I sprayed with Physan, but don't know exactly what I'm dealing with and would appreciate some help. Whatever it is, it seems to move pretty fast.

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Physan won't work on it.

I would cut the infected area and brush the wounds with cinammon first. Then I would use something like a systemic fungicide such as Phyton 27.

Give the plants some air circulation above the leaves with a fan.

I've got 2 fans, so lots of air circulation. Bellina leaves are so soft--I don't want to damage healthy tissue any more than necessary. What would you suggest cutting with?

That is a bacterial infection, not a fungus. A type of brown rot, likely Erwinia.

With a flame-sterilized and cooled knife, cut a wide margin around the infection into healthy tissue. You can do the cinnamon thing on the cuts, or not.

Keep drier than usual for a few weeks until yo are sure it is not coming back.

I provide extra calcium (gypsum, 1 teaspoon/gallon) to my plants, it seems to help prevent diseases.

I would use a sharp knife(razor) to cut the rot out. The knife would need to be soaked in bleach and I would use a lighter to sterilize the knife.

I grow bellina with a day temperature of 28C and at night the temperature is 20C with humidity of 75-85%. They grow under a single T5HO 24Watt light that is 12 inches above them.

If I see a black spot on the edge I just use a q tip and brush some diluted Phyton 27 and the spot drys out the next day. Rot usually tell me that I need to get air circulation up!

---------- Post added at 04:41 PM ---------- Previous post was at 04:37 PM ----------

The use of calcium is a good idea or you could get a Cal-Mag from a hydroponic shop that has the right amount of Calcium to Magnesium ratio.

I agree, it looks more like a bacterial infection and not a fungus. I also think you need to cut that section of the leaf. That kind of thing can spread quickly. Unfortunately phals are susceptible to bacterial problems. Good luck.

Sorry to hear about your orchid. Having dealt with both 'Black Rot' and 'Brown Rot' in the past, I understand how you must feel. If it is either of these, they can both be contagious so you want to move the orchid away from the others. You will also have to examine the other orchids for the next few weeks to make certain it hasn't spread.
Isopropyl alcohol is really good at stopping bacterial infections and the spread of fungus as it dries and disinfects. If this is spreading very fast, you might as well remove the leaf, then swab everything but the roots very well with a cotton ball swabbed in the alcohol (I use a new cotton ball for each leaf). Keep the orchid dry and where there is good airflow for a few days. You will have to keep examining the leaves to make certain more little spots do not form (indicating that it has spread).
Milk, at one time, was used as a fungicide/bactericide by some gardeners before the advent of chemicals. It only works as a preventative, however. Black Rot is often an indication of calcium deficiency (I learned this the difficult way) but I'm not so sure about Brown Rot.
Good luck on saving it!

---------- Post added at 10:11 PM ---------- Previous post was at 10:08 PM ----------

I think you could get by with only cutting the infected part with some of the healthy leaf surrounding, then treating everything with alcohol. The infection doesn't look too bad. I had entire leaves turning brown...within a few hours. :(

I'm wondering if a recent late in the day watering is behind this. The bellina hangs just 3 feet or so from an oscillating tower fan, so I think it gets good circulation. But I may have left leaves wet later than I should have a couple of days ago.

I do supplement with calcium, but am not very disciplined about how often. Good to know that attention to that can help.

Hate to cut this previously perfect gorgeous leaf, but sounds like that's the only way to safeguard the plant.

thanks to all of you for the fast feedback. You guys make a great pit crew :)