Fungus?

[Stone]

This has probably been coverved before but would appreciate any ideas.
A couple of my Paph. bellatulum are developing a browning tip on the leaves.
It starts at the extream tip of the leaf and very very slowly makes its way
down the central vein not affecting the rest of the leaf at all. I know I could
cut it off but I would like to know what it is or what's causing it.

 

[eggshells]

Is it salt build up on the medium?

 

[SlipperFan]

Does the tip feel dry, or a bit moist?

 

[Stone]

Definately dry to the touch and it can't be salt build up because I use one-eighth streangth feed and flush well often.

 

[Paph_LdyMacBeth]

I don't grow brachy's but I have found with other paphs this can sometimes be caused by low humidity as well (or at least increasing humidity stopped this from happening as frequently).
Other things that can cause browning is mechanical damage (are you maybe getting the tips of the leaves caught in between pots?), general age, or as others have said salt buildup. I would imagine different types of fertilizers, ratios, and such could cause this (ie too much of one type of nutrient), but I can't speak to that.

 

[likespaphs]

could you post a photo?

 

[Stone]

Sorry not ste up for that yet but imagine a thin brown line running down the very center of the leaf and moving really slow. I'm talking 1mm a month.
I dabbed a little cinnamon/alchohol on and that seems to have stopped it but who knows?

 

[Rick]

"salt leaf tip burn" I think is just another symptom of excess K. It almost doesn't matter how frequently you flush the pots, but ratios of Ca/Mg to K and overall amount of K during feeding.

Goes back to bad growth of niveum seedlings.

I would repot and choke the K way down in future feedings. Add some form of crushed dolomitic limestone to the potting mix.

BTW you mentioned that your basic irrigation water was acidic. Do you know the hardness, alkalinity, pH and eC of your basic water?

Usually acidic waters are very soft with very low amounts of Ca and Mg.

 

[Stone]

I use rain water collected from the roof so I imagine it has next to no nutrients in it apart from the odd bird offering. ec dosn't even register and ph
is about 6

 

[Rick]

I use rain water collected from the roof so I imagine it has next to no nutrients in it apart from the odd bird offering. ec dosn't even register and ph
is about 6

A lot of the problems you are sharing with us are similar to what I've been experiencing over the years (with me using straight RO water).

Things like leaf tip burn, stalled seedling growth, root burn with Vanda, erwinia.... have become marginal issues since I started cutting 10% of my very crusty well water with the RO water I was exclusively using before, and replacing most of the K in the feed with Ca.

I still end up using a "soft" low salt water with hardness 20-30 ppm and alkalinity of 10-15 ppm pH is closer to 7.

But that starts the system out with a bit of Ca/Mg and silicates not in the RO water.

 

[valenzino]

I agree with Rick,I had same problem cause my well water is nearly pure.Solved the problems with fertilizers and for Paphs adding white marble in the media and useing epson salts.

But for bellatulum this can be also a problem due to high temperature.That species is very sensitive to too high tremps and becames very suxceptible to illnesses.

 

[eggshells]

I am using a product called cal-max to my regular fertilizing regime. It says:

It says it prevents leaf tip burn and blossom end rot in tomatoes. I figure might be the same for orchids too.

 

[Rick]

I am using a product called cal-max to my regular fertilizing regime. It says:

It says it prevents leaf tip burn and blossom end rot in tomatoes. I figure might be the same for orchids too.

You're pretty close to on track with this eggshells.

I know a lot of us have been growing a lot of stuff successfully for years, but usually with just a handful of persistant problems and accomodations.

One for me is that I couldn't get ANY phal to survive if I grew it in a pot (regardless of media), but they generally did good for me when mounted. I always considered this an excessive watering problem. But when I cut K down and replaced with calcium (keeping N stable) I was amazed as to:
1) I have some potted phals doing just fine now
2) A few mounted plants that were on the verge of death (atributed to disease) are turning around at a fantastic rate
3) the plants I thought were doing good to start with are doing better than I've seen in the last 5 or more years.

I still have my first orchid (my wife gave me a hybrid phal in 2001 Valentines day). It grew like mad at first, bloomed like crazy, and then was on a downhill slide for the last 3 years. It looked crappy this winter, and I thought I was going to lose it. But in the last 6 months its been growing roots like mad, and new leaves big and stiff. I just spotted a new flower spike yesterday too.

 

[Stone]

I am using a product called cal-max to my regular fertilizing regime. It says:

It says it prevents leaf tip burn and blossom end rot in tomatoes. I figure might be the same for orchids too.

I also bought myself some Cal-max even though the container didn't say
what form of Ca was in it. After a search I found it was calcium chloride!
It's still in my shed unopened.

 

[eggshells]

I also bought myself some Cal-max even though the container didn't say
what form of Ca was in it. After a search I found it was calcium chloride!
It's still in my shed unopened.

I didn't know that! Good to know. Although I have been using the product in a while now without any problems (touch wood). Actually I was looking at dynagro products at first but they only have mag-pro so no calcium on it. Perhaps you can use magnesium sulfate and calcium nitrate instead? Maybe Rick can recommend other source of calcium and magnesium supplements.

 

[Stone]

Over here it's often recomended to use gypsum (cacium sulphate) but all the
samples I've checked are contaminated with limestone (ph9).

 

[eggshells]

I was checking the chemical composition of the Cal-Max. Are you afraid that calcium chloride might hurt your plants?

 

[Stone]

This is what I found about Chloride:
It is usually the first ion to produce recognizable symptoms: ( yellow margins or tips of leaves extending and evenually turning black).
Increases succulence of leaves leading to greater risk of fungal attack.
Whether using a small amount in your liquid feeds will have these affects, I
don't know but I'll wait for you to let us know

 

[eggshells]

Interesting. What I found is calcium chloride is abundant in the environment and too much of it may do harm than good. Just like everything else in this world. However the reason why we are applying it is because of the deficiency in the first place? I don't know as I am not an expert. I have not seen the symptoms that you describe but you sure got me worried lol!

 

[Rick]

I don't know if I would sweat the chloride that much. Since eggshell is already using it and hasn't seen any problems the calcium is doing more work than the chloride is causing problems.

Looking at what hits niveum, exul, concolor, godefroyae in the wild (i.e salt water) chlorides are obviously not a big deal to those species.

It's hard to generalize about peoples surface waters, but it's not uncommon to see 20-30ppm of chloride in most drinking waters (that growers typically use for watering orchids).

So dilute amounts of calcium chloride probably isn't going to put any more chloride into your plants than most growers get anyway from using drinking water.

However, I use calcium nitrate for my soluble calcium boost. Calcium sulfate (gypsum) is probably fine to, but has limited solubility (its a pain to dissolve). Bone meal (calcium phosphate) has been used in horticulture for years too, but its also not very soluble. Marilyn LeDeux (who I think is a fantastic Phrag grower) uses it routinely in her potting mixes.

You might also look at some of the Cal/Mag boosters from some other fertilizer brands. These will probably be some combination of calcium nitrate and mag sulfate (epsom salt). Recently I came across a cal/mag product (that I have not tried) for turf grass management that has calcium and magnesium chelated in organic sulfur materials (organo-sulfonates of some type). These may be really, good to try, but I have too many other things to play with already.