Cymbidium seedling leaf tips turning brown

[Tsuchibuta]

I was in the greenhouse today and noticed that 30 of my cymbidium seedlings, all the same cross, all have browning leaf tips. Could this be fungal? I want to stop it before it kills all my babies.. None of the other seedlings in my greenhouse are exhibiting this browning. The leaves are not dry and the mix is damp but not really wet. Do I need to cut the bad parts off all 30 plants.. if so is there an efficient way to do this and still stay sterile?

[Ross]

I'm not a cymbidium grower but I've never known leaf tip browning to be fungal. It typically signals fertilizer buildup in the mix or something like that. Adam (Stonedragonfarms) might be a good one to PM and ask personally.

[Tsuchibuta]

I haven't really fertilized in while (since bringing the plants in the greenhouse in October), perhaps they could use a repot it's been maybe a bit over year.. ripening mix maybe?

[orchids3]

Generally agree with Ross - When I lived in California I got a lot of leaf tip die back and always blamed it on the terrible water. It helped to flush the pots out. You might pull one plant out of its pot and see if it also has rotten roots. If so repot right away - also I would find out what the pH of the potting media is. If its below 6 look out.

[Bobfharris]

If you have young seedlings and overwater them the tips will turn brown, excluding excess fertilizer as the cause. High salt in the water will do the same thing as well, but most often it is just overwatering. You want to keep them from drying out but not too much. The amount will depend on your air circulation and ambient temperatures so I cannot say how often exactly. I usually do twice a week as a guide though.

[stonedragonfarms]

Interesting handle...aardvark...if these are dug-ups, it may also be that they are simply shedding their lower leaves (the ones that they developed in flask, and have had for the past 20 months or so)...are all the leaf tips browning/dying back, or just those of the bottom 2 sets (or so) of leaves?
Adam

[Tsuchibuta]

I have tried repotting some of them, they are just planted in sphagnum and it's still seems fairly fresh. It was damp but not sopping. I water with RO filtered cistern water. It's just very odd that is only these seedlings. I will continue to monitor to see if it gets much worse.

[Des]

We would need some pics to try and help you on this problem . In my experience there are a number of reasons for leaf tip die back
Fungal infection --this usually indicated by a thin yellow line at the base of the die back. I cut the leaf back well below the yellow line and seal the cut with sulphur . start a preventative spray program for fungus and sterilize the feed water ,most fungus is water borne .
Build up of salts within the pot- This often happens to growers who feed their plants large amounts of fertilizer once a month and forget to flush the pots . This is why many commercial growers now feed every time they water but at a much lower rate - the first indications of salt build are black speckles on the leaf tips, later progressing to the whole leaf tip . If you have this problem it is best to repot with fresh media.
Also remember that some cymbids are more salt sensitive than others ,for instance hybrids with Devonianum in the background are more likely to be salt sensitive.
To rectify this you need to change your fertilizing method
a ph imbalance within the pot --this is often caused by under watering which is caused by the fear of over watering !! My cymbidium seedlings are grown in hydroponics they are watered two to three times a day , flushing out spent nutrient, toxic gasses and deoxygenated water I have never lost a plant due to overwatering but have lost plenty due to underwatering !!
Adding dolomite lime and gypsum to your media will keep the media PH within tolerance .

[Des]

Just to add to what I have said above , I find that growing Cymbidium seedlings in sphagnum moss to be a waste of time as it only has a pot life of about 9 months before going very acid , try changing to chc.

[Tsuchibuta]

Here is a sample of what I've been talking about, I recieved them as part of a lot I bought from a nursery going out of business. They were already planted in the sphagnum when I got them a few months ago and they were really healthy so my experience has taught me that it is usually better to leave well enough alone. I think I will begin repotting them in coco husk chips, (that's what I grow most everything else). Anyway thanks for the info. I know Des says that he grows them hydroponically, I wonder if semi-hydo would work as well.