Phal + Semi-Hydro + Black Spots Underside of Leaves + Problem

[empiref]

Hello All,

Hope everyone is doing great.

This is my only phal among a couple of Oncidiums and 13 Cymbidiums; they are all potted in hydroton, semi-hydro medium.

When I water every week, I flush the pot and do a check of plants.

This phal, has been in semi-hydro for the past 2 years, no problems at all. Last week, I lost a leaf of the opposite side of the leaf in question now. The leaf was turning yellow from the top towards the bottom.

This week I saw some black spots on the underside of a leaf, second from the bottom, the black spots have somewhat a hallow around them. the black spots are about 30% visible from the other side of the leaf.

I sprayed the entire leaf underside and top with an undiluted 2% Hydrogen Peroxide, before snapping the pics and posting this thread.

Phal is outside on a covered balcony, that is closed up with a thick plastic transparent curtain, winter time now, high temp is 18 c and at night it drops to around 7 c.

I checked the other leaves, no sign of any spots either on the underside or topside.

the pics are attached below, any help would be nice.

thank you all in advance.

[Orchid Whisperer]

Hi empiref

I think your temperatures may be too cold, possibly your plant is on the verge of some mesophyll cell collapse, this is leading to some spots here and there that are getting bacterial infection (Erwinia or something similar). Your night time lows should be mostly around 15 C (roughly 60 F), though I have found some fluctuations a little lower are no problem. The 7 C (45 F) temperature is too low for an average low (though sometimes I have had Phals that briefly reached temperatures like that).

If possible, move your Phal to a warmer location. Watch those spots, cut off part (or all) of the spotted leaf if the spots grow or spread, even a little. If the cold is unavoidable, try to water only on days that are warmer than the typical temperatures you mentioned.

Good luck!

[empiref]

Originally Posted by Orchid Whisperer

Hi empiref

I think your temperatures may be too cold, possibly your plant is on the verge of some mesophyll cell collapse, this is leading to some spots here and there that are getting bacterial infection (Erwinia or something similar). Your night time lows should be mostly around 15 C (roughly 60 F), though I have found some fluctuations a little lower are no problem. The 7 C (45 F) temperature is too low for an average low (though sometimes I have had Phals that briefly reached temperatures like that).

If possible, move your Phal to a warmer location. Watch those spots, cut off part (or all) of the spotted leaf if the spots grow or spread, even a little. If the cold is unavoidable, try to water only on days that are warmer than the typical temperatures you mentioned.

Good luck!

Thank you for your help,

Like I said, yesterday I sprayed the entire leaf with an undiluted 2% Hydrogen Peroxide; hopefully that will do some good.

I moved the phal today outside because it is is sunny and covered it with a mesh cloth for shading.

I will keep doing that everyday as long as it is sunny even while it is cold, and at night I will pace it inside the house until the next morning.

I will keep you posted on the updates.