Is this a fungal infection on masdevallia mendozae? - Orchid Board

RandomGemini · #1 07-13-2014, 01:45 PM

Not sure what to do... I love this little plant. I have had it in my terrarium, but when I noticed that one of the tips of the leaves had turned black and there were some dark spots on the backs of other leaves and a couple of leaves turning yellow, I figured it was time to pull it from the terrarium and find out what's going on with it.

If it's a fungal infection, what do I treat it with and how?

It's such a tiny little guy, I'm afraid to get too aggressive, but I like it a lot, so I don't want to lose it to this either. It's potted in a 2 inch clay pot in pure NZ sphagnum moss.

james mickelso · #2 07-14-2014, 02:10 AM

Have a look at St. Augustine Orchid Society - North Florida Orchid Growing. Look under orchid diseases. You'll find your affliction there with lots of info to care for it. Most likely anthracnose.

rocio · #3 07-14-2014, 12:05 PM

Hi,
From what I've read (not an expert), sometimes the spotting of the leaves by fungus won't harm the plant if the spot do not grow or change... they just hurt the look of it

.
I use another source of information about pests and diseases that I love, because they have a lot of home remedy suggestions and I love their "do it all spray" (or something like that) recipe; one that's uses cinnamon, soap and alcohol. Also, they have an online store in case you need to go with something stronger. You'll find the remedies here:
Home Remedies

Good luck!!

Rocio

RandomGemini · #4 07-14-2014, 12:17 PM

I have trimmed back a couple leaves that looked like this already, assuming it was something minor that could be handled quickly. With new ones coming back, this is definitely some kind of disease.

Thanks for the link James! I'm thinking I should repot as well, was thinking I would do that today, but would it be better to do that after treatment?

Zoi2 · #5 07-14-2014, 03:14 PM

The fungal infection is most likely due to not enough air movement in the moist environment. These like it cool with a lot of air.
Joann

RandomGemini · #6 07-14-2014, 03:43 PM

Thanks Joann! As soon as I have this infection under control, I will move it. I had thought I could keep it in the terrarium, but I guess there's not quite enough air movement for it in there.

The tag says "mostly shade" but I grow my masdevallia veitchiana with my cattleyas, oncids and brassia hybrids and it's VERY happy there. Should I put this one in much brighter light as well?

naoki · #7 07-14-2014, 05:15 PM

To me, it looks like stressed Masdevallia rather than fungal infection. I haven't grown this species, but it is supposed to be cool grower, right? Some Masd. shows the dots when it is too hot. The leaves don't have the lustre of healthy Masd. (it could be the lighting), suggesting that the relative humidity may be too low. What's your humidity level and temp?

RandomGemini · #8 07-14-2014, 05:19 PM

83% and 73 degrees on the button. This plant was in a terrarium until about 20 minutes before I posted this.

When I suspected it had a fungal infection or disease, I pulled it from the terrarium to keep it from spreading. I moved it to my quarantine spot and put it in its clay pot on the table, sitting in a saucer of water, which is how I grow my masdevallia veitchiana.

The spot where it's at now, temp is around 74 degrees and humidity is around 40% in the room. Not sure what it would be around the plant where it's sitting in the saucer of water.

Zoi2 · #9 07-14-2014, 05:53 PM

73 degrees is a bit on the warm side for this plant. They normally grow cold to cool (50-65 degrees). Growing in moss is ok but I really don't think keeping it in a saucer of water with out a ton of air circulation is healthy for the roots. Are the roots able to get air? Just my 1/2 cent worth.
Joann

RandomGemini · #10 07-14-2014, 07:22 PM

I do not think this problem was caused by my conditions because I purchased the plant with a yellowing leaf on it and some black spots on the back of the leaves, but like naoki, I thought that it was caused by the plant being too warm and not getting sufficient light, so I just removed the yellowing leaf and went on with life.

I do think it's anthracnose as james suggested. The photos I've seen of this fungal infection look exactly like it, so I will begin treating for it tomorrow.

Masd. Mendozae is not an easy plant to grow and it IS a touchy orchid, however, the cloud forests that its native to, do get up to 80. This plant should have no problem tolerating 73 degrees based on where it grows in the wild. If it can't tolerate 73 degrees, then it's just going to die in my care, but that doesn't mean that I will stop trying to keep it alive.

The clay pot method is designed to keep the root zone cool, so if 73 is too warm for it, this method should drop the temp some. I learned this method from several other members here who successfully grow masdevallias.

The way it works is that the clay pot absorbs the water from the moss (loosely packed, never tightly packed) and from the saucer and the evaporation of the water from the porous pot keeps the root zone of the plant much cooler than room temperature. You want the water to just barely skim the bottom of the pot, so the media has a chance to dry out some too. Finding the sweet spot for the water level is kind of a trick, but once you've got it, this seems to work great. My other masdie is very happy with being grown this way.

---------- Post added at 04:22 PM ---------- Previous post was at 03:57 PM ----------

Thanks for your help everyone! Hopefully I can keep this plant alive! I'll post an update in a couple of weeks!