Paph. Leaf Tip Die-Back

[aerides]

I was having leaf-tip die-back with several paphs when I was growing in NYC. I potted paphs in straight sphagnum and used NYC tap water, which is generally considered very acceptable for orchids. The light was HID but the paphs were off to the side. There was fogger in the room that kept humidity at good levels. Probably was using 20-20-20 at 1/4 strength as a constant feed, monthly flushing with clear water. I remember hearing something about fertilizer salts bonding with sphagnum so they can't be flushed but don't know about this. I can't remember exactly which paph this was, possibly delenatii or a cross. I'm back into orchids at a different location so naturally I want to get paphs! It seems a good time to begin working on insight into this issue. Thanks for any help.

[Ray]

I usually chalk that up to either underwatering (or insufficient roots to take it up) or an excess of fertilizer.

Please describe the details of "1/4 strength" and "continuous feeding" - i.e., how much per gallon and how often.

[WeirdGuySeattle]

On these mottled leaf paphs, I have seen leaves die like this when they are growing too cold / wet.

[aerides]

Originally Posted by Ray

I usually chalk that up to either underwatering (or insufficient roots to take it up) or an excess of fertilizer.

Please describe the details of "1/4 strength" and "continuous feeding" - i.e., how much per gallon and how often.

Sure. 1/4 tsp. per gallon of a 20-20-20 type formula used for every watering with a monthly flush of clear water. Thanks for your response.

---------- Post added at 07:21 PM ---------- Previous post was at 07:12 PM ----------

Looking at this plant again, after a rather long period of time, it looks like it's growing "tight." And looking at the way the light is reflected off the leaves, there also seems to be slight puckering on the surface. So maybe a combination of over-lighting, slight underwatering, and excess fertilizer. There's even some bleaching in some of the older leaves.

[Ray]

Originally Posted by aerides

Sure. 1/4 tsp. per gallon of a 20-20-20 type formula used for every watering with a monthly flush of clear water. Thanks for your response.

That's about 65-70 ppm N, which is probably OK if used once a week. More often, and I'd cut the rate.

It might be an accumulation issue.

Tell us about the water supply and how long since you're repotted.

[aerides]

Originally Posted by Ray

It might be an accumulation issue.

Tell us about the water supply and how long since you're repotted.

I don' think the potting mixture was more than a few months old, at most. I dug up my records from those days (15 years ago). I found a note that I called the water department on December 17, 03 and received the following stats:

TDS: average 58 mil/ltr with a range from 28-132.
Potassium average 0.7 mil/ltr
Calcium average 7.6 mil/ltr

Another Manhattan grower noted at the time that the Ca/Mag levels are quite low but sodium content may be a bit high for "sensitive orchids". Also, the numbers above were averaged from both watersheds for NYC but that Manhattan (where I lived) received 90% of its water from the Croton system, which tends to be lower in TDS than the other one in the Catskills. Anyway, probably too much info but I found it interesting. A far different story here in northwestern New Jersey. It's bottled water until I can get my RO system.

[Ray]

Manhattan has some of the purest tapwater in the country, but as you don't grow there any longer, you had better look up your current water authority's reports, to know for sure what you're dealing with.

[aerides]

Originally Posted by Ray

Manhattan has some of the purest tapwater in the country, but as you don't grow there any longer, you had better look up your current water authority's reports, to know for sure what you're dealing with.

I'm sure. It's awful. So thanks for helping me with the leaf dieback issue. Less heat, a little more water, less feeding. Check! I could check the TDS in the bottled water I'm using, but from looking at the health of roots from other plants, I'm guessing it's fine for most purposes. RO on the way. And three new paphs!