Black Rot?

[estación seca]

Were the leaves firm, or wet and mushy? My first thought was sunburn.

And my next thought was calcium deficiency.

[Orchid Whisperer]

The more I look at the yellowing, which seems most common near leaf tips, the more I am thinking anthracnose, or a similar fungal disease. I would still consider treating with a SYSTEMIC fungicide like Cleary's (unlikely you will find it in conventional garden centers, should be available online, or if not sold in the U.K., find another systemic fungicide).

Estacion seca is right to suggest that more calcium could help. Calcium is important for disease control.

[monet]

Thank you all for your advice. I am carefully removing the black spots and sealing the ends with rubbing alcohol . I did not know about calcium for preventing decease. Also letting the plant dry out. Not found fungus Treatment yet.

[camille1585]

I wouldn't be surprised if you didn't find a systemic fungicide. If the UK is anything like other EU countries, all the effective chemicals treatments (i.e. all the systemics and a lot of everything else) are getting pulled from the consumer market to protect the environment.

It's getting increasingly difficult to buy "big guns" to treat anything. I had a look at the alternative natural treatments that are now filling the shelves, and the only insecticides are basically pure rapeseed oil sold at a ridiculously inflated price...

[monet]

Hi Camille, Thank you for reply. We must protect the bees but hope for safer remedy that wont cost so much . I am watching and cutting out any black spots out. An amazing amount of new roots are growing. Love the pictures of your orchids such variety of colors and shapes.