Phal. equestris - spotty leaves
 

Hi Orchid People,
I have made good progress with organising my numerous plants and have got some idea of what I have and how to look after them. I have a Phal. equestris (possibly) with what looks like a viral disease on one leaf, the rest of the plant looks healthy. This plant flowered for six months continuously this year so it would be a shame to loose it. See photos. What do you recommend that do? I would guess that I should chop off the leaf and burn it, then provide some kind of prophylactic treatment to rest of plant.

It looks like it has been munched by a pest, like a snail of slug, and black mold is starting in the damages spots. Personally I’d leave it alone until it naturally fell off, unless it really bothers you. The plant looks healthy!

I’d treat it for fungal infection anyway.

It looks like a typical case of an acidovorax (pseudomonas) infection. A copper-based bactericide should stop it from progressing.

Never seen that this far North. Nasty!

Hi Ray,
Thanks for your diagnosis - Psudomonas. You recommend a copper based bactericide, I have copper sulphate, what strength should I use? More than a month has passed and the spotting hasn’t spread. Other advice was to do nothing, easy to follow, and cheap too! :)
The plant looks healthy and is about to flower again. (Pic) I could of course, using sterile methods, cut the leaf off. I look forward to your wisdom.

As long as it isn't spreading, I'd just leave the leaf... it is still photosynthesizing and benefiting the plant. The new leaves look great. Eventually the damaged one will turn yellow and drop of its own accord. Let Mother Nature do her thing unless there is a really good reason to do otherwise.

It might have attacked during a particularly rainy and humid period, or a cool period. Are weather conditions different now?

Not really, hot and humid all year round. Maybe a little cooler in the next few months.