Black spot on cattleya roots

[soub1508]

Hello everyone.. one of my cattleya has produced many new roots recently but today I noticed some black spot on newly developed roots. Is it any kind of fungal or bacterial infection or something else?

[SouthPark]

Hard to say what it is due to. Since you have really nice roots, there's probably nothing to worry about. Just maintain nice temperature and lighting conditions, and maintain gentle air-movement in the growing area.

There appears to be nothing wrong with this orchid. Maybe just some mechanical damage --- developed a split or something, so some cells just died maybe, and became darkened.

Just monitor the situation. And - if you like - could allow for a temporary dry-out of the roots. And then proceed to water as usual.

[Roberta]

It looks to me just like darkening with sun exposure (not really sunburn though maybe it is a bit...) I see it on mine from time to time, no bad effects. I don't think it is anything to worry about.

[rbarata]

Agree with Roberta (my Catts also show spots like those).
Do you fertilize it? If so, how much and how often?

[soub1508]

Thanks everyone..I fertilize it at every watering around 25-30 ppm N . Once in a week I don't add fertilizer and flush the media with ro water(tds-19).so weekly I fertilize it with 150-180 ppm N. Is it enough for tropical climate?

[estación seca]

Many people fertilize the way you do. In a tropical climate where plants can grow faster some people do use more fertilizer.

Fred Clarke at Sunset Valley Orchids writes, in the orchid culture portion of his Web site, that he uses 100 ppm nitrogen on Cattleyas at every watering. He flushes without fertilizer only once a month. The seedlings I buy from him are larger than those from other vendors.

I use this fertilizer regimen; I find most Cattleya seedlings break multiple leads in each growth period.

Edit: One half teaspoon / 2.5 ml of powder of MSU formulation per gallon / 3.78 liters of water gives 102 ppm nitrogen. Measuring mass, 0.75 grams per liter gives 98 ppm nitrogen. I got these numbers from the fertilizer calculator on the First Rays Web site. I reinforce this is for plants growing in warm temperatures with good light.