Help with Dendrobium

[rodrigosf]

Hello everyone! I'm Rodrigo from Brazil and I'm new to this forum, thank you for accepting me.
I've been growing orchids for about a year, so I'm not very experienced yet and would like your help identifying a problem with my Dendrobium.

After flowering, it grew sprouted three new plants and they have been growing just fine until 2-3 weeks ago. I noticed some dark spots on the keikis' leaves and some weird coloring too. These pictures are from two weeks ago:



The next days, I noticed the leaves kept getting weird and now they look pretty much all-damaged. Here are some pics I took today:



Does anyone have any idea what might be happening to them? I looked everywhere but have yet not found a solution to this specific problem.
Thank you so much in advance!

Rodrigo

 

[Djthomp28]

Hi Rodrigo, and welcome to the forum!

The damage to the underside of the leaves makes me wonder about mites. They are small and hard to see. Some people use a jeweler's loop or some other 10x magnifying glass. An alternative that I use is to take a white paper towel or tissue and wipe the underside of the leaf. Discoloration might be indicative of mites.

Have you had any changes in your growing environment? Humidity or watering regimen? That may help to narrow in on other causes if no mites are found.

Regarding the circled areas on the tops of the leaves, I am thinking mechanical damage.

Let's see what others see.

 

[rodrigosf]

Hi Rodrigo, and welcome to the forum!

The damage to the underside of the leaves makes me wonder about mites. They are small and hard to see. Some people use a jeweler's loop or some other 10x magnifying glass. An alternative that I use is to take a white paper towel or tissue and wipe the underside of the leaf. Discoloration might be indicative of mites.

Have you had any changes in your growing environment? Humidity or watering regimen? That may help to narrow in on other causes if no mites are found.

Regarding the circled areas on the tops of the leaves, I am thinking mechanical damage.

Let's see what others see.

Hi! Thank you for the help.

I don't have a magnifying glass, but maybe I should get one. Is it actually impossible to see them with naked eye?

Yesterday I wiped the leaves with diluted hydrogen peroxide to see if it helps.

Regarding changes environment changes, in the past month we had a sudden change in temperature and humidity where I live (it's Winter now in Brazil). The average daily temperature was around 78 – 88 F, and now the days are starting at 55 F and going up to 75 throughout the day, with humidity a little lower than it was before.

Thanks again.

 

[big923cattleya]

To me it looks like spider mite damage. I agree with DJ that a white piece of paper can be held underneath a leaf. Tap it and hopefully the mites will reveal themselves.

Now, the Dendrobium group in general are best grown tightly packed into a pot. Their roots like to be pot bound. They hate repotting. Yours seems to be a nobile type Dendrobium. They require a lot of water. I grew them well using small clay pots in a mix of chopped Sphagnum moss, fine bark, fine charcoal and perlite. In a pot with media such as you show, in my experience, they will be harder to grow. They do not like to dry out.
They are heavy feeders among the orchid family with regular applications of fertilizer at half strength. When the new growth matures, when the small terminal leaf appears, you reduce watering and cut feeding. When they grow dry and cooler, buds with form along the canes and they bloom on both old and new canes.
The take a bit of morning sun. Temperature range of the low 50’s through the upper 80’s. But they won’t be happy in constantly warm conditions.

 

[IvoPhal]

Agreed with the opinions above spider mites and then weakened flower susceptible for other problems. Try by step with proper insecticides and then we’ll see the results, good luck!