Help for yellowing leaves

[murcielago]

Hi it is my first post here, and I am really pleased to have found this forum. I've been growing paphs for about a year and I hope to learn more for all the other experts here!

Some of the paphs I have been growing are turning yellow with interveinal chlorosis, some on the older leaves and some on the newer ones. I'm not sure if it is due to heat stress or mineral deficiency, but I've been supplementing with magnesium sulphate and it doesn't appear to be working. My care regime is as follows:

Temperature: 26 -28 'C year round (I live in a tropical climate)
Humidity: Probably never falls below 60% under ambient conditions.
Light: I'm growing them under shade. No direct light at all, but I get very bright reflected light from my neighbour's whitewashed building that bears the full brunt of the tropical sun.
Potting mix: Primarily pumice (it is basic; tested it out with red litmus but I don't know the exact pH value) with lava rock, chopped sphagnum, a sprinkling of dolomite and limestone chips if required. I get pretty good root growth with this mix, extensive with nice white tips.
Fertiliser: Gaviota 63 at 1/4 dilution, alternating with amino acids and magnesium sulphate (epsom) weekly.

Here are the plants.

P. exul with pale new leaves. The veins are a darker green.

P. lowii with yellow green leaves and green veins on the older leaves. Newer leaves show this faint mottling as well, but it is less prominent. Too much light?

P. praestans, prominent veining in the newer leaves.

P. spicerianum. I know the temperature range is way to warm for this, but it usually gets by fine and has been known to bloom in a tropical climate. I'm suspecting heat stress for this one. Interveinal chlorosis on the older leaves now. The green leaf is a new one.

I really hope someone can point me in the right direction for this one. Thanks!

 

[paphioboy]

Hello and welcome to ST Which country are you from? The top 2 plants do not seem too yellow to me. Try giving them a small teaspoon of Osmocote fertiliser. I find that it helps green up plants instantly... The spicerianum is on the yellow side though. I think we need a pic of the whole plant to better diagnose the symptoms..

 

[likespaphs]

have you checked the leaf axis for mealybugs?

 

[NYEric]

Welcome from NYC. The spicerianum looks a little yellow but if it's an old (dieing) leaf then no big deal.

 

[murcielago]

Hi no mealy bugs. Checked already.
The larger yellow leaf is from an old growth that has bloomed, so maybe I can be a little less concerned about that. Regarding the smaller yellow leaf it is the oldest leaf on a growth that is still pushing out new leaves. Is this possibly indicative of something more insidious?

 

[NYEric]

Except for the spicerianum, I dont think your leaves are too yellow at all.

 

[likespaphs]

The larger yellow leaf is from an old growth that has bloomed, so maybe I can be a little less concerned about that. ...

do you know that each growth will only put out one inflorescence (flower stalk)? after the stalk dies, the growth will die.
the plant should put out new growths, which will then mature then flower then die, so on, and so forth....

 

[murcielago]

Yup I do. But the yellowing progressed really quickly and turned from bright green to the yellow above in a month. But if it isn't anything to be worried about than I'm relieved. Thanks for the reassurances.

 

[Heather]

I agree that the first two look okay to me. The third one with the yellow older leaf - I used to find that this sometimes happened rapidly on old growths when a new growth or root had started coming out through or just under the old leaf. Wonder if that might be going on here?

 

[SlipperFan]

I agree with the others that the only one that might be of concern is the spicerianum. But if that is the old growth that has bloomed, and the new growths look fine, then it is just the the old growth is dying, which is normal. A photo of that whole plant might be helpful.

 

[Hien]

In the past I have used this product called METANATURALS ORGANIC NITROGEN with absolutely stunning result.
I have never seen any product or stuff produces such a result overnight like this one.
You can see a deep deep green color the next day, absolutely overnight like they advertise. No fertilzer burn.
I put the pot w/plant inside a second outer pot same high , mixed the liquid fertilizer with distilled water. and fill to the top of the media (in my case hydroponic pebbles)
- I leave the stuff in for example my phalanopsis, all of them turn deep green, I can tell that the leaves plump up. Even the seedling in the compots grow very fast & very green too.
You may want to change the water after a while (your choice of how long here) and flush the plant with pure water.
The only draw back is that:
-This stuff is a little bit stinky, but not very offensive at all.
- And they don't sell really tiny size of this fertilizer bottle. I end up having so much left , and after a few years it looks spoiled.

http://www.planetnatural.com/site/image.html?sku=metanaturals-organic-grow

 

[SlipperFan]

That's interesting, Hien. I remember Jan Szyren (MSU orchid grower) once saying that when she sees any of their plants looking a little yellow, she just gives the plant an extra dose of MSU fertilizer. More nitrogen.

 

[Hien]

That's interesting, Hien. I remember Jan Szyren (MSU orchid grower) once saying that when she sees any of their plants looking a little yellow, she just gives the plant an extra dose of MSU fertilizer. More nitrogen.

Yes, this thing is pure nitrogen, organic, & nothing else. It is so simple for the right need

 

[suss16]

Is that any different than Calcium Nitrate? 15.5-0-0?

I really do not know the definition of organic in this case...

 

[Hien]

This is what they say in the brochure:
The product was made with natural ingredients such as seaweed, compost etc...
That is why it is a little bit smelly.
However I did not try it on the leaves themselves.

http://www.planetnatural.com/site/metanaturals-organic-grow.html


The most powerful liquid organic nitrogen available in the world! See results within 24 hours in a nitrogen deficient environment. Great for building green growth and promoting a rich microbial environment in the soil. MetaNaturals Organic Nitrogen (16-0-0) combines the power of North Atlantic kelp, and plant and animal composts to supply a powerful organic nitrogen field. Helps build green growth throughout the plants life cycle. For use in soil or in hydroponics. MetaNaturals Organic Nitrogen meets current guidelines for fertilizer used in organic food and fiber production. Use 1 tsp. / gallon of water.

Directions for use:

Hydroponic Application - For manipulation of nutrient mix to accelerate growth or correct nitrogen deficiency add to reservoir in 1/2 to 1 tsp. per gallon increments. Observe results for 24 hours. Repeat if necessary. May be used with mineral nutrients.

Soil/Field Application - Mix 1 Tbsp. / gallon of water and apply as a side dress at 2-4 week intervals. It is important to use an adequate amount of water during application to conduct the nutrient solution throughout the root zone but not so much as to create excessive runoff. Fewer applications of greater concentrations are acceptable.

Foliar Applications - Plants will absorb foliar applied materials much more quickly than soil applied fertilizers. Mix with water and apply to plant foliage starting in the 4-leaf stage and repeat at 2 week intervals. Use 1/2 the rate of Soil/Field amounts. Apply as a fine spray until leaves drip, using a wetting agent if necessary. Best when applied just before or just after sundown.

 

[murcielago]

Hi thanks everyone for the contributions. Recently I've started administering epsom as a solution to the roots instead of foliar feeding. I've noticed a greening effect on the lower leaves, comfirming my suspicions on a Mg deficiency due to Ca overload. Some are not responding though, but I think I won't fret too much over it especially if it is on a small leaf or a flowered growth.

Here is a picture of my spicerianum. The plant is actually about two tones more yellowish than the picture as I could not accurately reproduce the yellow colour on my camera. What do you think?

 

[paphioboy]

That is one big spicer plant... Try more shade or increased fertiliser, as many people have recommended..

 

[SlipperFan]

Looks like you are on the right track.

 

[Justin]

they look healthy to me. nice plants.

 

[Pete]

all of your plants look fine. do not fret. all previously flowered growths whither away to nothing sooner or later. grow them shadier. give them a little urea if you want to green them up.