Cattleya black new Leaf tips

[braxtonds]

I have a Blc. Orange Nugget x C. lawrenceana 'Blushing' orchid growing in a 6" clay pot with coco/bark mix that is 1/3-1/2 filled with a net pot/lava rock on the bottom for drainage. I tended to overwater in the past so I tried for this drier combination this time when I repotted this past spring.

Here is the plant:


I haven't had any major issues at all with this plant until this year. Most if not all the new growths have developed black tips. They seem to dry up and prevent the new leaf from opening. The new growth can be seen because they are more purple/red than the old growths.





In addition, a few large black spots have occurred and appear to go right through the entire leaf. I keep my entire collection outside all summer, under the porch roof (no rain water.) I water either from hose or excess pond water so the water can set on the leaves but tends to be mostly dry by night since I try to water in the morning or midday. I live in Ohio so the nights are colder.

Any ideas would be greatly appreciated. Thanks.

[Leafmite]

Do you give your Cattleyas extra calcium? If not, start. I use eggshells for long-term (they have to decompose to release calcium so this is not immediately helpful) but you will probably need to find a supplement to help now.
Why do I suggest this? Some years ago, I switched from using my goldfish pond water to distilled water and orchid fertilizer. I did not realize that orchid fertilizer did not contain enough calcium for my orchids (most fertilizers that are specific contain whatever that particular group of plants need but not orchid fertilizers, apparently). In the fall, I discovered 'black rot' which wiped out most of my Cattleyas and some of my other orchids. It was caused by calcium deficiency. So, when I hear of this sort of thing happening with Cattleyas, my mind always jumps to calcium deficiency. Good luck!

[campchi]

Maybe sun burn? Not sure what causes...maybe someone with more experience can pointed out.

[Oscarman]

The reddish color in the new growths to me says maximum light is being experienced. The leaf tips.....too much light, calcium deficency....I am leaning towards the light issue.

The black oval black spot looks like heat/light stress - overheated tissue dying and collapsing. I have it on a C. dowiana too!

[braxtonds]

Thanks, no, I don't use calcium and I'll definite look into it. Would you suggest crushed oyster shells? I don't eat enough eggs for my whole collection haha. How do I know how much to add to the pot. Also, with winter that cuts down the sun and heat, that should help me identify if the spots were caused by sun damage.

[campchi]

You can go to any pet store to buy calcium bome that are for birds...that can be use as well. It's cheap, I usually get it like $1/piece.

[silken]

To me it looks like sun burn and heat stress too. But I am a convert to Cal/Mag supplementint also after having un-explained black spots on a lot of my orchids-mostly Catts. So far it seems to make a difference. I got a supplement from a hydroponics store.

[NYCorchidman]

I second the sun burn on the black oval marks.

Overall, the plant looks heat stressed.
Do you leave this cattleya out in the sun??

[braxtonds]

I leave the orchids on the porch under a roof, it receives sun till around 11am-noon

[tucker85]

I agree with Leafmite and Silken, any time new cattleya growth gets fungus problems, it's a sign that the plant is not getting enough calcium. The crushed oyster shell, that you mentioned, is one possibility. Some growers use dolomite lime to increase calcium. Another option is to switch to a cal/mag fertilizer. Personally I use a supplement called MagiCal that you can buy in hydroponics stores.