Phal bacterial infection

[lauraeli]

Second year in a row I had to cut two leaves off one of my mini phals due to a bacterial infection. This is actually the 3rd time this particular phal has had this issue but none of my other phals have had it. Any reason why a single phal might be prone to it, and anything I can do to help prevent it in the future?

All of my phals are in the north window. Last year when it got infected, it was in the east window. The roots are very healthy, it's potted in sphagnum. I water it on an as-needed basis which lately is about every 3 days. I have a fan on in that room constantly.

Here are some pictures of the leaves I removed

[jkofferdahl]

That looks more fungal than bacterial! Typically, such issues are caused by an excess of water. A Phal being grown in sphagnum, and in a north window, which is being watered every three days would seem to me to be getting too much water. Sphagnum works like a water magnet, and plants I have in it (I repot quickly to get rid of it) seem to hold water for 10 days to 2 weeks. I'm not saying you're overwatering because I can't see the sphagnum, but every three days really worries me.

[lauraeli]

This is the plant in question. It is in a 3 inch slatted pot. It is in a room with a running fan all day and I only give it about an ounce of water. I watered it the day before yesterday and it is crispy dry.

[lauraeli]

Or maybe I watered it 3 days ago. Its hard to say since I dont go by the number of days when I water, and I never remember when the last day was that something was watered. I just look at it and say, 'does it seem to need water and do I feel like watering it' which lends itself, not surprisingly, to underwatering.

Edit: I have been watering it more than usual lately so perhaps this particular phal actually appreciated the prior neglect.

It does have a particularly healthy root system compared to most of my other phals and has never showed signs of water stress so, may be on to something here...

[jkofferdahl]

That looks pretty dry, so I suppose my first stab was off. Is it possible that cool water has gotten onto the leaves at night, and especially on cooler nights?

[Roberta]

Originally Posted by lauraeli

This is the plant in question. It is in a 3 inch slatted pot. It is in a room with a running fan all day and I only give it about an ounce of water. I watered it the day before yesterday and it is crispy dry.

Cold water on the leaves (or condensation, perhaps a drip from the window?) could cause the damage. It may be that this plant is more susceptible to infection than the others. But as far as watering... rather than a small amount of water often, the plant would prefer a good drenching (which will wet the media thoroughly) less often. Water until it runs out of the pot (under the faucet is even better). That washes salts out of the media, and pull air into the root zone. Then, neglect until the media is barely damp, and repeat. If you water in the morning, the occasional stray drop or spray will have plenty of time to dry before it gets cold in the evening.

[lauraeli]

I feel I should be more specific about the leaf spots. There is previous leaf damage on the first leaf, with unknown cause, but that aren't in question. So I circled the areas of concern. Note that there are two pictures for two leaf- one with light shining on it, and the other how it looks with light shining through it.

The outer leaf surface is smooth and dry. The spots are brown and slightly sunken, with a watery outline most visible from the underside of the leaf. The areas surrounding the brown area are yellowed and allow light through. While I did not leave these leaves on long enough to say for sure what they would do, previous experience is that the area spreads if not removed.

[lauraeli]

I tend to water in the mornings, occasionally I do water at the end of the day. Usually when I do this I will put them on the stove with the vent fan on. They dry very quickly in that spot and it also keeps them away from any cold drafts from the window.

I cant specifically rule out water on the leaves but I don't believe this is merely cold water spotting.

Whatever it is, the cold temperatures are a risk factor, as i dont recall it happening during the summertime

---------- Post added at 04:08 PM ---------- Previous post was at 03:59 PM ----------

I forgot to mention that the older damage (the damage not circled) may be cell collapse from temporary exposure to cold.

[Orchid Whisperer]

Bacterial brown rot or brown spot (Erwinia or Acidovorax). You can get the yellow halos around the rot areas with either disease.

Cutting, as you did, is the right treatment.

I see this most often when a Phal gets too cold. Not every Phal will be affected the same way, even at identical temperatures. Bacteria coming from the lesions may keep re-infecting your plant.

If you have cut enough that you are seeing no new spots, you should repot. I recommend a medium, like bark, that dries faster, and a terracotta pot. Before repotting, remove all medium from the plant. Don't rinse, except possibly the roots. Wipe every leaf, top and bottom, with a paper towel and hydrogen peroxide. Change the paper towel frequently, repeat until you have gone over all leaf surfaces 2 or 3 times and the paper towel comes away clean. Allow the plant to dry bare root for a day (this won't hurt it). Repot into DRY bark. Don't water for a few days keep eyes open for new spots. When you are seeing no new symptoms, resume watering, roots only.

Long term, you should consider providing supplemental calcium to your fertilizer regimen. It helps with disease prevention (I use gypsum, 1 teaspoon per gallon of water; I also add the same Amount of Epsom Salts.

Good luck!

[lauraeli]

I didnt know that about calcium and i should definitely add it to my regimen.

As far as potting medium goes...I individualize it to the plant. I grow some in sphag, some in bark, and some in a 50/50 mix. But Im an under-waterer. My phals tend to dehydrate in bark. Out of 10 phals, only three are in a bark mix without sphag. The first one because it is P. schilleriana (tough little guy) and it was in orchiata when I bought it. And the other two because they are in large pots.

I wouldn't switch this one to bark because the roots are happy in sphag.