Have my Phal's caught a virus/disease?

[Kratos]

Have my Phal's caught a virus/disease?


This is a new experience for me so hope someone could help. These are the only ones affected although all my orchids are looked after in identical ways...

Two leaves have already gone completely, yellowed and fallen off, but what ever is going on seems to be working its way up the plant, oldest leaf first... I get leaf drop happens with age, but even to me this seems excessive and there is no sign of new growth to replace what's going.

The orchid with the white flowers and yellow lip, is branching left right and center so thought perhaps it was under stress, but the other affected plant has no buds/spikes in development at all. Very strange...

(Sorry for the poor picture quality, my main camera is out of action)

[camille1585]

Very strange, phals never have that many leaves turn yellow at once!
The chlorosis looks like they may be suffering from a nutrient deficiency. Are you fertilizing it, and if so, how often with what? The yellow margin on the leaf of the blooming phal is one of the sympyoms of magnesium deficiency. Or it could be a nitrogen deficiency as the yellowing usually starts on the older leaves and works its way up. Are the yellowing leaves still firm, or do they become limp quickly? How much light are they getting? Too much light can make plants turn purple (which is fine) and eventually yellow.

[Undergrounder]

The plant is under stress, probably from having to deal with all those flowering spikes. It's feeding on a few leaves to get a quick fix of energy to keep the flowering going.

Edit: I didn't see that you have two plants affected, one without spikes... hrmm.. Check the roots?

But don't worry no virus problems that i can see!

[mehitabel]

Since the leaves are dying from the bottom up, my guess is that the leaves are dying because the roots are compromised. Unpot it gently and check the roots.

Can you remember where the yellow starts? A leaf dying normally would start yellowing from the tip and the yellow would move toward the stem. This would indicate dryness (and/or poor roots). The oldest leaves would be affected first.

Sometimes a leaf yellows from stem rot, in that case the yellow begins at the stem and moves to the outer portions of the leaf. In this case, several leaves could be affected at the same time, or top leaves before bottom leaves, etc.

[quiltergal]

I think it's definitely time for a root check. It's not normal to have that many leaves yellow and fall off at once. If they both have a compromised root system then you will need to repot ASAP. Cut the spikes off the flowering plant to save it. Put the cut spikes in a glass vase and they will keep for quite a long time. Let us know what you find out.

[Kratos]

Hi!

Thanks for the replies, quite a range of answers!

- I do fertilise every couple of waterings (waterings being generally once a week) with a special baby bio orchid feed...

- I'm not overly keen on pulling the plants out of the pots again (only put new growing media in at the start of the year) BUT will do if you are sure I need to (Enclosed is a picture of the roots inside the pot), never had a problem with roots before so think a root problem is unlikely.

- Perhaps they have had too much light. On a North facing window and as the Earth is now in a position for the window to receive sunrise sun the ledge gets quite a bit first thing.

[mehitabel]

The roots in that picture look ok, so unpotting seems unnecessary, as you say.

Too much sun does cause damage either in the form of hard yellow-green (not the shade of yellow you have, which is death-yellow) or white or black burn-patches.

Given the additional information you provided, my guess is stem rot from too much water (or dew) caught in the leaf junctions, maybe compounded with temperatures that are too low.

To stop any stem rot, Physan 20 is a good contact anti-bacterial, anti-fungal that gives protection for several days after application.

Check your night temperatures-- any extended period below 60F can be damaging.

[Des]

Try foliar feeding your plants with a plant booster at half strength, Remember that phals like a higher nitrogen feed than most orchids . It does look as though you have a nitrogen deficiency. The flower spikes and new leaves are drawing their nitrogen requirements from the older leaves

[Kratos]

Originally Posted by Des

Try foliar feeding your plants with a plant booster at half strength, Remember that phals like a higher nitrogen feed than most orchids . It does look as though you have a nitrogen deficiency. The flower spikes and new leaves are drawing their nitrogen requirements from the older leaves

- This seems the most logical as its the only variable that is changeable... could they go like this with too much feed as well?

Thanks everyone for your suggestions! Think I'm going to try the feed suggestions first. By the looks of it i don't have much time left before total collapse of the plant .

[Gwenchanter]

To me it looks like you need to put this plant in a bigger pot! The roots are packed very tight in there and perhaps need a bit more space. I don't think this is what is making your leaves turn yellow though. I would tend to agree with one of the first posters who said that your plant is probably exhausted from all of the flowers it has produced and has nutrient deficiency. I would say it needs to be fertilized every single week. The roots look healthy to me. If it were my plant I would cut off all the inflorescences to give it a good break and let it recuperate, especially if it only ends up having two leaves left which looks like might be the case. There's no way only two leaves will be able to support huge branching inflorecences like those.