Quantcast

Yellowing leaves

Slippertalk Orchid Forum

Help Support Slippertalk Orchid Forum:

P

PHRAG

Guest
I have this problem. It has happened to phals, a couple of neofinetia, one or two miniatures and a couple of other species. It is not a pest issue that I can see.

This is what happens. Leaves, usually the oldest leaves on the plant, begin turning yellow and eventually fall off. It happens one leaf at a time. In a couple of plants, the leaves have all fallen off, one at a time. Humidity and temperature are not any higher than usual, and I actually cut back on the amount of time I leave my lights on because I think maybe my plants are getting too much light. Some were looking very pale, but now they are greening back up again. I don't think it is crown rot, because the plants actually stay alive. Some just lose one or two leaves, and in a couple of cases I lost the whole plant but the roots were still healthy. Very odd indeed.

Any ideas?
 

gonewild

Grower
Joined
Jun 26, 2006
Messages
5,139
Reaction score
4
Location
Puerto Maldonado, Peru
PHRAG said:
I have this problem. It has happened to phals, a couple of neofinetia, one or two miniatures and a couple of other species. It is not a pest issue that I can see.

This is what happens. Leaves, usually the oldest leaves on the plant, begin turning yellow and eventually fall off. It happens one leaf at a time. In a couple of plants, the leaves have all fallen off, one at a time. Humidity and temperature are not any higher than usual, and I actually cut back on the amount of time I leave my lights on because I think maybe my plants are getting too much light. Some were looking very pale, but now they are greening back up again. I don't think it is crown rot, because the plants actually stay alive. Some just lose one or two leaves, and in a couple of cases I lost the whole plant but the roots were still healthy. Very odd indeed.

Any ideas?
Air pollution?
Can you post photos?
 
P

PHRAG

Guest
Lance, I will post photos next time it happens. Right now, none of the plants are losing a leaf. It happens pretty quickly. The leaf turns yellow and within three days falls off completely. No other signs of disease, and the plant usually keeps on growing just fine. I would think it was just old growth dying off, except for the two plants that didn't make it.
 
P

PHRAG

Guest
Not as regularly as I should be. I am, and in low doses, but not every time.
 
P

PHRAG

Guest
Point taken. But are you sure it couldn't be aliens or something? :)

I guess I need to start taking better care with my fertilizing regime.
 

dave b

Well-Known Member
Joined
Jan 1, 2007
Messages
240
Reaction score
0
Location
Dayton, Ohio
The Feb issue of Orchids has an article (part 2) about Phals. In it is a brief talk about the use of potassium and effects of lack of. Seven phals were used in test, given potassium levels ranging from 0 to 500ppm. Interestingly enough, the phal at 50 ppm dosage shows definite yellowing of older leaves. The Phal at 0ppm dosage appears dead, with practically all leaves gone (one severely shriveled leaf left). They quote that all plants suffering potassium deficiency over time died. The other Phals exhibit healthy looking growth, full green leaves, with good blooms. Optimum potassium levels were listed at 200 -300 ppm. Research was conducted at Texas A and M. What i cant find, though i read it recently, is how the ppm dosage corresponds to guaranteed analysis: by wt. that we commonly see posted on our fertilizers.

I too have seen some yellowing, especially on a couple Phals. I have been fertilizing pretty light for a while, and am upping it a bit on these plants.
 

Rick

Well-Known Member
Joined
Jun 9, 2006
Messages
12,765
Reaction score
3
Location
Leiper's Fork, TN
Also when was the lat time you repotted? I grow almost all my phals mounted so I don't generally see this problem, but a bunch of phal growers near me often atribute stuff like this to sour old mix and chlorine in the irrigation water.

Dave sounds like he has some good info too.

You can't get 200 ppm of K out of any natural waters, that will require fertilization. But the ability to extract minerals from the environment is often pH dependent. Often those old acid mixes promote too much uptake of trace metals and nutrients.

There's lots of variables. Also I often get yellowing and leaf loss when humidity is low (rather than high). Reducing light is probably a good try too.
 

Latest posts

Top