HELP!! BLACK PATCHES ON DENDROBIUM!

[H.D]

HI!
My Den. Bullenianum has developed these black patches. i am concerned that it may kill the plant!
what should i do?

[Roberta]

Are the black areas firm, or mushy? "Mushy" would indicate an infection, but if firm, whatever it is, likely just on the surface. What temperatures has the plant encountered? This is a warm-growing species so cold could do this,

[H.D]

Thanks for the reply!!
i just checked, the patches are firm! so hopefully no serious damage!
yes it has been cold , the lowest was yesterday, 8 degree celcius in the night, but it always gets around 20 degrees celcius in the morning.

[Roberta]

I think that is probably too cold for that species... It is from low elevations in the Philippines, and probably wants something like Phalaenopsis temperatures. Minimum around 15 deg C (60 deg F)and as much warmth during the day as you manage. This is just a guess on my part based on what I can learn about the species since I don't personally grow it. But if it is outside, consider bringing it into the house for more warmth.