Fungous or bacterial problem?

[Brabantia]

Here is a picture of two leaves of my Paph. wilhelminiae I take this morning. This is not the first time I see this disagreement on Paphiopedilum or Phragmipedium. Is this a fungous or a bacterial problem. I must added that I spray a little macozeb (Dit..ne) on the bottom of the leaves (around all the two months) ... is this good?
Of course I took away these ill leaves with a disinfected scalpel.

 

[Shiva]

It is mostly normal for old paphs and phrags leaves to die back after a while. Fungus and bacterial problems won't normally happen if humidity is kept at a reasonable level and if plants are watered early in the morning with good ventilation all the time. In drier conditions, paphs can be attacked by red spider mites which can have leaves look like yours. A powerful (15x) magnifying lens will tell you if any of those bugs are present.
Personnaly, I have no problem with fungus and bacterias in phrags and paphs. But I regurlarly have to fight off red spider mites in paphs in winter and for that, I mostly use Safers' Insecticides. I've never had a phrag attacked by spider mites as far as I can remember.

Michel

 

[Shiva]

Forgot to mention one possible other cause. Check out the roots. It may be time to repot the plant in new media.

 

[Rick]

I agree with the first part that old leaf die-back is normal, but I find it often is accelerated by low humidity problems and poor nutrition.

Many of these jungle plants come from areas with minimum humidity levels of 60-70% with rains that could go on for days.

If your oldest leaves are dieing back without the growth blooming or starting a new growth then I would also check roots, but I would probably increase humidity (not by increased watering though), and maybe change the feeding regime.

 

[fibre]

I think the sunken surface of that leaves is a typical damage of false spider mites (Brevipalpus).

IMO the sunken dots on the young leave (marked with red ) look like Brevipalpus too. Usually the fungus or bacterial rot use the damage of the mite to attack the leaves of the Paph. So I see two problems on your Paph.

Any other opinions?

 

[Brabantia]

I agree with the first part that old leaf die-back is normal, but I find it often is accelerated by low humidity problems and poor nutrition.

Many of these jungle plants come from areas with minimum humidity levels of 60-70% with rains that could go on for days.

If your oldest leaves are dieing back without the growth blooming or starting a new growth then I would also check roots, but I would probably increase humidity (not by increased watering though), and maybe change the feeding regime.

Thank you all for your responses.
@ Rick Now,I can see the bud in the heart of the leaves, but I agree I have stopped feeding it because we have a very poor daylight actually and I hold around 60°F in the greenhouse. The humidity is around 40. Outdoor night temperature is 18 °F actually.

 

[ehanes7612]

i agree with Rick, this actually looks like a normal process for wilheminae and anytime you repot older leaves tend to die pretty quickly

 

[Erythrone]

40% humidity... if hygrometer is not accurate, maybe it is less than 40%. I have 3 differents hygrometer and they are never at the same % if I put them side by side. I checked their accuracy last year:

http://www.sciencecompany.com/barometric/hygrometers.htm

One was 5 % less, another 10% more, and the other one 5% more!!!

A few years ago I bought 2 hygromether. One of them was always between 25 to 30%. The other one (hair) was always more than 50%...

 

[Rick]

Spider mites are often symptomatic of too dry a condition also.

40% is too low for both the plant and exacerbation issues with mites.

This time of year with north winds blowing, its pretty easy to have humidity levels of less than 40%, even in a GH. So even if your present hygrometer is not accurate, I'd be doing something about it.

 

[Erythrone]

I agree!!! It's too low!

 

[Brabantia]

Thank you all for your interesting responses.

 

[Brabantia]

Thank you all for your interesting responses.
My question was in relation with the post I have initiated in the Culture section (About fertilizers of Slipper Orchids).

 

[Ricky]

Spider mites are often symptomatic of too dry a condition also.

That´s right but: tropical false spider mites like higher humidity levels. http://www.hark-orchideen.de/Pflanzenschutz/Brevipalpus/biologie.php?lang=en&navID=99

 

[Orchidzrule]

That´s right but: tropical false spider mites like higher humidity levels. http://www.hark-orchideen.de/Pflanzenschutz/Brevipalpus/biologie.php?lang=en&navID=99

Ricky, I checked out the link and it's most informative, but none of the control measures mentioned are chemicals I've ever even heard of! Do you, or anyone else in this forum, know of other controls for false spider mite? Does Safer's work?

 

[SlipperFan]

Try a product called Sucra-Shield. Ray sells it (www.firstrays.com).

These mites are very tiny -- you need a strong magnifying glass to see them. And you should treat all the plant and every plant around it if you find them. They can move quickly across a collection, and they seem to love Paphs, Dendrobiums and Phals, especially.

 

[Orchidzrule]

Thanks, Dot. I will look into it. I'm not totally sure it's what I have, but the leaves are similar to those in this thread and I definitely see pitting. Most appreciated!

 

[Rick]

That´s right but: tropical false spider mites like higher humidity levels. http://www.hark-orchideen.de/Pflanzenschutz/Brevipalpus/biologie.php?lang=en&navID=99

Also Brabantia is not experiencing high humidity levels, so I wouldn't expect her to have the tropical spider mites. So by increasing her humidity she could kill two birds with one stone.