Brown spots on Catt leaves

[gngrhill]

Hello all, My Psycho Bride just got done blooming and I saw brown spots all over the blooming growth. It got looking pretty bad, so I cut the PS off at the base. It has a new growth about half grown, and now that also is developing brown spots. The rest of the plant looks fine. I have read previously that a lack of calcium can cause Catts to develop brown spots. Is this accurate ? Seems funny that it is only happening to the new growths. What do you think ?

[katrina]

Pics would help w/diagnosing. How are you growing it right now? Watering, light, etc?

[gngrhill]

Originally Posted by katrina

Pics would help w/diagnosing. How are you growing it right now? Watering, light, etc?

Culture has really not changed. It's under the T-5s during the day, gets watered once or twice a week depending on how dry it gets. When the temps get above 80 or so it gets lightly misted once or twice a day. Does not get misted when it's cooler than that. I fertilize every other week weakly, rinse pots once a month. Water is half tap (has calcium and other minerals in it ) and half rain water. Hope this helps as the last blooms began to spot as the spots got worse on the PB. I'm afraid that because this PB is already spotting, the blooms may come out spotted.

[wintergirl]

I give calcium to all my catts. I sprinkle dried crushed egg shells on top of the media. You may want to use something more fast acting, but when I started getting those spots I just used the egg shells and never got any more. Here are a couple of pictures.




There are a few threads about low calcium in catts on this board. If you are using 1/2 rainwater and tap water it may not be enough calcium. Some catts need more than others. I give calcium to all my catts and I have hard well water.

[gngrhill]

I did put some eggshells on the Catt with the spots. How long do you think it takes to make a difference ? I also put some crushed eggshells in a cup of water thinking that maybe the calcium might leach into the water and then I could water with that. Sound feasible to you ??

[Leafmite]

Eggshells take a while to decay enough to release calcium, especially when they aren't in soil. If you have signs of calcium deficiency, you probably need an immediate source. You could go to a hardware store or garden center and get some commercial product or you could boil eggs, fish the eggs out, save the water and cool it, and use it to water the orchids. If your orchids were outside, you could add a little powdered milk to your watering can (would smell bad indoors).
I really don't know what the brown marks are. When I had calcium deficiency (went from using pond water to using fertilizer with rain water), it was the classic case...the new growth would turn black and then it would spread throughout the other growths. I didn't find any orchid info at the time for what was happening but it reminded me of when other plants suffer calcium deficiency so I started the eggshells (something recommended for herbs) and have not had that happen again.
Good luck!

[katrina]

Looks more fungal or bacterial to me...doesn't look like Ca deficiency. I would stop misting (it doesn't do much for the plant anyway) and try to increase the air movement.



Side note...the roots look awfully dry and withered. Better, more thorough watering will help this...misting won't. This time of the year most orchids are using a lot more water since they are actively growing. I would shorten the dry time between waterings to accommodate the rapid growth that's occurring during these warmer months.

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[wintergirl]

Even if it's fungal or bacteria, it could not hurt to make sure you have calcium in your media. Every one of my catts has a sprinkle of egg shells, I have not gotten a black spot since.

[Leafmite]

I am always adding eggshells to my orchids to keep a steady supply. According to other gardening experts, Calcium also prevents fungus and bacterial problems. I have heard that it strengthens the cell wall but I am not entirely clear on the science behind this. Some old-time gardeners have told me that they spray milk on the leaves of their plants to prevent fungus infections when there is quite a bit of rain and high humidity (outside, of course). They swear it works. I have not tried it.

[wintergirl]

Originally Posted by Leafmite

I am always adding eggshells to my orchids to keep a steady supply. According to other gardening experts, Calcium also prevents fungus and bacterial problems. I have heard that it strengthens the cell wall but I am not entirely clear on the science behind this. Some old-time gardeners have told me that they spray milk on the leaves of their plants to prevent fungus infections when there is quite a bit of rain and high humidity (outside, of course). They swear it works. I have not tried it.

Do you use egg shells on all your orchids? Phals? Vandas? Milts? ect? Are there any you don't add them to?