Brown Spots on Tips of Dendrobium Nobile Leaves

[KristenJ]

A couple of days ago I noticed a leaf on my Nobile Dendrobium had a brown tip. I thought it was turning yellow to drop off, so I wasn't concerned. However, now I have several of the leaves with these brown tips. It is only happening on the new growth. The older canes are okay.

I searched through the link from the top of this forum & think I might have salt toxicity. I've attached pictures for second opinions.

This nobile I have been treating for mealybugs, so it has not been receiving fertilizer, as I have been trying to get the pests under control first. I water it with filtered PUR water once a week. It is in a bark-like mixture. The roots sticking out of the top & sides of the pot appear to be as healthy as they have always been. I also do not see any crusty/salt buildup around the pot. None of the other dendrobiums are experiencing this problem.

If anyone knows the cause & how I can go about fixing this, I would really appreciate some advice! Thanks

[Leafmite]

With what do you treat you den for mealy bugs?

[KristenJ]

Hi Leafmite,

After trying Rose rx (which has neem oil as the main ingredient) with little progress, I posted to Orchid Board for help. I used Bud's "cinnamon soak" in May twice and never saw another mealybug since until about 3 days ago. The soak consisted of water (I used my PUR pitcher to filter tap water), a couple of drops of cinnamon extract & liquid dish soap.

[KristenJ]

I thought some more photos might help identify the problem. Today I noticed that some of the tips have dried up, while others now have a pinkish/purplish band at the border between the brown tip & green leaf.

I also have a new problem. I came back from vacation today & the leaves on the new cane of my Dendrobium Phalaenopsis Hybrid have yellowed at the tip with small black dots. I have attached pictures in the hopes that someone might have some ideas. Thanks all.

[Bud]

you need to repeat the soap mix every two weeks intervals and two weeks rest in spraying because the eggs can be hidden on the nooks and crannies and on the media mix....its not a danger to the plant or humans only the insects and bugs are affected so you can even use the mix as a watering regimen

the dried leaf tip can be cut and wipe both sides of the leaf with hydrogen peroxide or brown listerine....to rule out fungi infestation(notice the yellow edge of the dried leaf tip=fungi)

also every two weeks flush the pot under full throttle faucet for 5 minutes to remove the salt deposits and material debris waste from the plant roots

do not hold fertilizer this warmer growing months...fertilizer doesnt react with your bug mix

[KristenJ]

Thanks again Bud. I did the soak for about a month and a half, even though I didn't see any mealybugs after the first soak. But then I stopped. I will restart it.

Are both plants experiencing fungi problems then? Do you know what I might have done that could have led to this?

When cutting the tips off, should I sterilize the shears between cuts? Do you recommend I use alcohol or flame? I've heard of using both.

Do I need to treat the growth medium for fungi? If so, any recommendations?

Also, do I need to separate these two from the rest of my orchids? I already did just in case, but I hate to remove them from their window where they're happy.

Lastly, do you think cutting the leaves off of the new growth will harm the plant too much? For my Blue Boy, its leaves haven't even fully spread from the cane yet. I hate to mess this up and hurt them worse.

I'm sorry, that's a lot of questions! I really appreciate your help.

[Wynn Dee13]

I think it could be just low humidity causing the brown leaf tips. Many thin leaved orchids get brown leaf tips. It also is a sign of fertilizer burn or too much salt build up in the media. You can cut them off like Bud said and yes sterilize your tools in between cuts. Don't use alcohol it doesn't kill viruses. Either torch your tools or soak them in a bleach solution (make sure you rinse the bleach off before cutting). Then dab some cinnamon powder on the cuts. It might not be fungal and you might not of done anything really to cause it. Who knows for sure what it really is and what caused it so don't beat yourself up about it. Maybe they need more air flow. I don't think you need to treat the media unless it spreads a lot. If it spreads rapidly then yes, separate them from your other plants. It shouldn't hurt the plants to cut off the tips. If they were my plants I wouldn't cut them at all unless it spreads. Some people think the brown leaf tips are ugly enough to cut them off even if it isn't harming the plant. I don't show my plants so I don't mind looking at some blemishes. Of course in a perfect world there wouldn't be any blemishes but to me it comes with growing orchids. Good luck!

[RosieC]

I agree with Wynn.

[KristenJ]

Thanks everyone. I did the flush in case of salt toxicity. I cut the tips off (sterilizing with flame between all cuts) of all of the leaves that were brown/yellow. I used cinnamon & neem oil after cutting. My Nobile is not showing any other problems (soil, roots, canes all look good). When I was cutting the hybrid's leaves (that's the pic where the leaves were yellow with black spots), I also pulled it from the pot to check roots. I noticed a white, I guess spider-web or dust bunny looking substance throughout the soil. Not sure what it was & forgot to take a picture. I guessed it was a fungal growth, so I sprayed it with neem oil after flushing. Thanks again everyone for your advice.

[KristenJ]

Hi everyone,

My nobile seems to be doing okay now, after cutting the brown leaf tips off. However, my Blue Boy (hybrid) still has yellowing leaves and brown tips. After cutting the tips, the cut site turns brown as well. The browning has spread down and now appears on the cane, which has also turned more yellow/brown than green. Does anybody have any ideas as to what might be causing this? Thanks again