# Lots and lots of yellowing leaves.



## kentuckiense (Jan 2, 2007)

I was out of town from saturday to monday evening. On friday I watered everything and turned off the fan because I wouldn't be around to monitor moisture levels. When I got back yesterday, I noticed a lot of leaf yellowing on older leaves. These yellow leaves weren't crispy or anything, they were still fleshy. The veins were yellow while the areas in between were sort of a translucent brown. It was the same on both Paphs and Phrags. Also, I noticed quite a few plants had their white root tips brown over. Not rot, just stopped actively growing.

My first thought was that it was heat stress from the fluorescent lights. They plants are between about 6 inches and 1 inch from the two bulb 48 inch T12 fixture (which is on for 14 hours a day). I put my hand under the lights and I thought I could feel the heat from the light even though the bulbs were fine to the touch. After all, my fan was off for a few days.

Second thought was that they are reacting to the lower humidity since I moved home from school. That was two weeks ago, though.

At every watering I use 1/4 teaspoon of MSU to a gallon of distilled water. I have yet to see fertilizer burn. Everything grows in CHC or bark.

Any ideas?
(Happy new year, by the way!)


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## gonewild (Jan 2, 2007)

Can you post some pictures?
Is the problem widespread or limited to certain plants?
How low is your humidity now that you have moved?


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## Rick (Jan 2, 2007)

gonewild said:


> Can you post some pictures?
> Is the problem widespread or limited to certain plants?
> How low is your humidity now that you have moved?



Is the yellowing more on older leaves?
What is your night temp?

I'm also interested in the humidity issue since I used to see more yellowing and leaf drop of older leaves before I started humidity control.


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## kentuckiense (Jan 2, 2007)

gonewild said:


> Can you post some pictures?
> Is the problem widespread or limited to certain plants?
> How low is your humidity now that you have moved?



I'd say it is fairly widespread. Some plants aren't affected, but I'd say most are. Luckily, most of my 'prized' plants are unaffected.
Humidity is in the 40-50% neighboorhood. At school the humidity is probably 15-20% higher. We use natural gas heat, but the heater is WELL away from the room in question. Could that be a cause?

Photos:

One growth of a Paph. Armeni White is turning really yellow (it had been doing that for a while, though):






A (niveum x bellatulum) x niveum with a few old growths turning yellow:





A Paph. Gloria Naugle seedling:





sanderianum seedling:


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## bwester (Jan 2, 2007)

the browning makes me think bacterial..... throw some bleach on it...... oh wait, that only works on non-living things, phyton man.


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## Rick (Jan 2, 2007)

In these photos it does seem to be focused on old growths and lower (older) leaves, so I think it is more humidity related.

In my earlier days I would see a fair amount of this. I don't think allot of my paphs (especialy brachys) enjoyed the low humidity, and when I compensated by increased pot watering they would shed leaves and growths.


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## kentuckiense (Jan 2, 2007)

Rick said:


> In my earlier days I would see a fair amount of this. I don't think allot of my paphs (especialy brachys) enjoyed the low humidity, and when I compensated by increased pot watering they would shed leaves and growths.


Yeah, this is probably the situation. A lot of the plants in CHC need to be put into more open mix that more evenly dries.


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## gonewild (Jan 2, 2007)

My first guess after seeing the pictures is something toxic.

How is you NG heating vented?
While you are home do you have more ventilation than while the house was closed up when you were gone?

I would look closely at possibly ethylene gas generated from your heating system.

The leaf death is a rapid decline of healthy tissue as evidenced by the soft looking area. It does resemble bacterial but is pretty wide spread without any lesions. I don't think your humidity is low enough to cause the sudden leaf collapse.

In the meantime make sure your house is vented while you are in it until you check your heater exhaust.


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## kentuckiense (Jan 2, 2007)

gonewild said:


> My first guess after seeing the pictures is something toxic.
> How is you NG heating vented?


Umm... I don't think it is. One of the heaters has a blower to move the heat some.



gonewild said:


> While you are home do you have more ventilation than while the house was closed up when you were gone?


In this case, yes. I turned the fan off while I was gone.



gonewild said:


> I would look closely at possibly ethylene gas generated from your heating system.


Will do.

Thanks for all the help, everyone. It's so frustrating having tons of stuff that should be getting ready to bloom but then stressing the hell out of 'em and delaying any blooming.


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## gonewild (Jan 2, 2007)

kentuckiense said:


> Umm... I don't think it is. One of the heaters has a blower to move the heat some.
> 
> In this case, yes. I turned the fan off while I was gone.



I mean ventilation with fresh air from outside not just air movement. Like open windows or doors or vents that would dilute or disperse any gas accumulation. It takes very little ethylene gas to cause plant tissue death.

It is possible your heater has a vent problem, if this is the cause then your plants may be your canary in the coal mine.


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## kentuckiense (Jan 3, 2007)

gonewild said:


> I mean ventilation with fresh air from outside not just air movement. Like open windows or doors or vents that would dilute or disperse any gas accumulation. It takes very little ethylene gas to cause plant tissue death.
> 
> It is possible your heater has a vent problem, if this is the cause then your plants may be your canary in the coal mine.



We have no outside vents, but our house certainly isn't sealed up airtight.

As for the second part, we've got a carbon monoxide detector, so hopefully we're covered!


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## terrestrial_man (Jan 3, 2007)

If unsure about the possibility of gas leakage call your gas company up and have them check it out. They have the equip. that can sense gas leakage even if you cannot smell it.


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## Heather (Jan 3, 2007)

gonewild said:


> It is possible your heater has a vent problem, if this is the cause then your plants may be your canary in the coal mine.



In other words, Zach - are you sure there isn't a problem with your gas heater? Maybe worth having it checked.


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## NYEric (Jan 3, 2007)

I think it was just the lack of air circulation combined w/ the excess water. Be glad the plants didn't die.


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## Eric Muehlbauer (Jan 3, 2007)

I would suggest also checking the roots....I have found that a symptom of sudden root loss is frequently multiple yellow leaves...its easy to think that the yellow leaves have a different cause, as you would expect to see shriveling with root loss, but I have found that leaves can yellow with root loss and remain quite firm. Don't panic yet...there are many cause for that kind of yellowing, but its good to at least rule out the roots...take care, Eric


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