What is causing my newest growth on my Cattleya dowiana to turn black?

[Alvaro78]

Hello guys!

This summer I purchased a Cattleya dowiana knowing full well they are not easy to take care of. When it arrived it had a new pseudobulb forming and some weeks laters new roots appeared so I decided to repot. After the repot the roots continued to grow so I thought good news. Sadly some days later I noticed that the latest growth had a small black patch at the tip that has since then been increasing in size.

I wanted to know what may have caused it? Does it look like sunburn or maybe it has to do with the watering? Or maybe it is black rot (please no...)? I know dowianas like to dry out between waterings so I have been allowing her to do so.

Also another question if someone knows about this species. Should I now start backing off on the watering and fertilizer to accomodate for the winter ""rest"" she needs? The rest after the info I gathered will consist of no fertilizer and way less waterings.

Thanks a lot!

[estación seca]

That's the classic appearance of lack of water. Small Cattleya seedlings especially shouldn't dry out completely when making new growth.

Lack of calcium can cause this, but since you got it recently, that's unlikely. The previous grower probably fertilized adequately.

Don't reduce watering Cattleyas until new growths are completely mature.

[Alvaro78]

I see, I thought it wasn't lack of water since I have adjusted all my media for my Cattleyas so that I water when they are all dry at mostly the same time. The rest of my Cattleyas are fine so that's why I'm a bit confused. Should I cut out the black part with some healthy tissue? I noticed the black part has some small white dots which might mean it's rotting? Thanks a lot!

[rbarata]

I would not cut anything. Increase watering might be enough.
Madrid in the summer is too hot, even at night, which may be the cause for plant stress. Also, the environment indoors during the winter is, usually, too dry due to heating / AC. That's something we sometimes don't consider but it's enough of a reason for watering increase.

[estación seca]

I'm saying not to let them get dry. Water when they are still moist. I think it is incorrect to let Catts become dry during the growing season. Much old advice applies to growing in wet greenhouses, not homes with low relative humidity.

[Alvaro78]

I understand now. I guess I will just have to increase the watering. If the black spot keeps increasing should I cut it? I am afraid of it reaching down into the base of the pseudobulb. Thanks a lot!!!

[estación seca]

The black is the part that died from lack of water. It will eventially become brown and dry, and easy to break off with your fingers. I would not cut it. You might remove more than necessary.