Brassavola seedling leaves got blackish lines along midrib

[sweta]

Hello Orchid pals,

Need some help in identifying leaf issue on a brassavola nodosa seedling that I ordered from olympic orchids 2 months ago. It was doing well until last couple of days leaves have developed dark lines along the midribs. Its potted sphag moss and medium pine bark chips. I water whenever medium dries out and I keep close watch on it since its a seedling. I've recently moved it away from window sill due to cold weather. Im and placed it under LED growing lights. Fertilize it every alternative week. House temperatures are around 70F and humidity about 30%. Could this some kind of fungal infection? Or could it be cause by the growing lights? Please suggest what could be the cause for this.

[MateoinLosAngeles]

I don't see anything to worry about. Minor color variations on the leaves are normal in orchids. It can be simply that the plant is maturing. You can use Liquid Copper Fungicide (Phyton 27) as a preventative in a Brassavola.

The LEDS are fine. Your humidity seems extremely low to me.

Remember they grow on cliffs and trees in the lowland of coastal mexico, they're mostly lithophytes, they like extremely airy medium and high humidity... feel the waves on their leaves... Lol I wonder if your pot might be getting too soggy for them. They hate that.

Brassavola is an intermediate temperature that likes bright light and very airy medium. I keep mine in a net pot in 75% bark, 15% leca, 10% sphagnum. Water weekly or biweekly depending on weather and I let it get bone dry. Grows like a weed.

Hard to know if this has anything to do with fertilizer without specifying your feeding regime. But try to target 100 ppm N weekly or 300ppm N monthly. Does your fertilizer provide enough Calcium?

Other issues that could be: hard water, purified water (salt accumulation), a virus, mechanical damage, cold damage, or something with the orchid being unhappy...

Go through the list and if you're providing everything right then keep observing if the spots expand.

[sweta]

Thank you for the response. This seedling came in sphag moss so I thought of not changing the media drastically since its a seedling..so I added some bark but has more of sphagnum moss. After seeing your post I removed the sphagnum moss. I find it a challenge to keep up with watering in dry home temperatures. You are right that the roots have been in wet soggy sphagnum moss. In addition the warmth from the grow lights might have cause some kind of infection. Can I use physan instead of copper fungicide. Btw I use rain water with repotme fertilizer.

[sweta]

Originally Posted by sweta

Thank you for the response. This seedling came in sphag moss so I thought of not changing the media drastically since its a seedling..so I added some bark but has more of sphagnum moss. After seeing your post I removed the sphagnum moss. I find it a challenge to keep up with watering in dry home temperatures. You are right that the roots have been in wet soggy sphagnum moss. In addition the warmth from the grow lights might have cause some kind of infection. Can I use physan instead of copper fungicide. Btw I use rain water with repotme fertilizer.

Here is another picture. The bottom part of leaf is turning dark.

[MateoinLosAngeles]

Originally Posted by sweta

In addition the warmth from the grow lights might have cause some kind of infection. Can I use physan instead of copper fungicide. Btw I use rain water with repotme fertilizer.

Idk what kind of grow lights you use but the LEDs I use don't really increase the temperature and are generally safe to use. It's hard to tell if you're experiencing rot by the photo, but that'd be most likely be due to staying in a wet and soggy medium with insufficient drainage or aeration.

The instructions for mixing on repotme fertilizers leads to 200ppm N, which is fine if you do biweekly. I'd use half strength or less weekly. Btw the Repotme fertilizer is the MSU fertilizer which can be obtained at much cheaper prices at Kelley's Korner, I use K-lite from FirstRays.com

I use both Physan 20 and Liquid Copper Fertilizer. I drench the entire plant and medium in Physan 20, if I have root rot I may let medium soak in Physan for a couple of minutes. Then I spray Liquid Copper Fungicide on leaves. I've never had a problem but I also will say that I haven't done this with my Brassavolas (I've done it with Cattleyas however). I got my Brassavola as a seedling and it had very vigorous growth potted in an airy basket with fine bark (And some leca and sphag), so I've only used Quantum and Kelpak on it, but not fungicides or pesticides.

If that is rot then you need to cut the pseudobulb, apply cinammon, use Physan 20, etc., etc. classic rot instructions you can find anywhere. But make sure it's rot first. As I said it looks fine to me, probably the roots will appreciate being in an aery medium and aery pot.

[estación seca]

A year-round maximum of 70 degrees F is probably too cool for a seedling of this plant, and most other Cattleya alliance plants. They won't grow strongly and will be more susceptible to other problems. It does tolerate much cooler overnight temperatures when older, but the following days are usually much warmer. In habitat it is a warm to hot growing plant. It grows in a lot of light, so leaves are further warmed by the sun. This is plant that easily tolerates Phoenix day temperatures, though, like other plants with succulent metabolism, it struggles when we have night temperatures over 85 F / 30C.

I can't see the photos well enough. Under high light even seedlings of this plant can develop purplish pigmentation along the midribs.

At a relative humidity of 30% you have next to no risk of fungus. I would not blindly treat with antifungal chemicals.

Another possibility is infestation with juvenile scale insects. I have received seedlings that turned out to have juveniles scale, which sometimes took months to reveal themselves. They preferentially cause damage with multiple tiny pits in crevices, and the insides of developing leaves. It looks a lot like the damage you are showing. If you have a high-powered magnifying glass try to see whether you can see any juvenile scale insects.

[sweta]

It doesnt look like rot. I'm very careful when watering and dont allow water to get into leaf joins. I use this growing light

Amazon.com

Roots look very healthy. I'm suspecting due to sphagnum moss being wet all the time must have caused too much of humidity. It was doing well on the window sill only after moving it away and putting it under grow lights I'm seeing this.

Thanks for information on alternative to repotme MSU fertilizer. Its actually very expensive in repotme. So glad to know other options.

[MateoinLosAngeles]

Originally Posted by sweta

Amazon.com
.

I highly doubt those lights are too hot since a Brassavola is an intermediate to hot grower, unless they're literally touching the leaves, but you can place them pretty close.

As Estación said, this plant can show purple/dark dots on the tips if it's getting enough light, not really in the creases but if it's not spreading, it could really be anything. A virus can't be ruled out, for example. But I do think that plant looks okay, it just might be a bit sluggish due to conditions not being optimal.

Think of day temperatures of 75-80ºF and 65ºF-70ºF at night. It'll be happier towards the warmer end of the spectrum.

It doesn't need super high humidity but it does need something closer to 40-50%. 30% is too low.

Keeping soppy Sphagnum plus cold temperatures will equal the sluggish growth you're seeing. Is the pot too big? The bigger it is, the wetter it will stay.

Regarding fungicides, I personally use them as preventative, especially with new plants. In this forum people are not very keen to that idea, however, you will see literature that recommends fungicides as preventative as opposed to treatments. Many growers use them monthly or at least twice a year (Seasonally). Norman Fang talks about drenching many of his plants in Physan 20 monthly.

I only do it with newer plants both to protect my collection and to give the newer plant a shot at being protected while it adapts to the new environment. Then as they get established in my environment I start a routine of watering with Quantum Total, over time the beneficial bacteria in Quantum will outcompete pathogens so fungicides really become unnecessary. Besides, they would kill the beneficial bacteria as well.

In your case I would look into finding a way to keep this plant airy (net pots, bark medium, air circulation), well lit (grow lights, windowsill), more humid and warm (perhaps a heat mat or a mini greenhouse).

So TL;DR: the plant is too cold.

[estación seca]

Fungicides are used as preventative measures in commercial nurseries growing in crowded greenhouses with high relative humidity where fungi can spread rapidly. They use numerous fungicides in rotation, never the same one twice in sequence, to prevent emergence of resistant fungi.

At household relative humidities there is almost no risk of fungal activity except in terrariums. Fungal attacks in hobbyist collections are usually caused by poor growing conditions - either too wet and cold, or too warm and humid - and the plants will do better if growing conditions are improved rather than the situation dealt with by using fungicides.

Fungicides are toxic to humans as well as fungi. Preventative use of fungicides indoors will not only select for resistant fungi, it will kill beneficial fungi that are known to inhibit the pathogens.

[sweta]

Hey @estación,

I've tried to click few more pictures. Please have a look. If its scale what can I do help this seedling? Please suggest. I tried cleaning the leaves with Dr Earths natural fungicide. Also can I identify juvenile scale? Its so hard to identify scale in juvenile stages. Can a baby scale insect form a small shell around it that could appear as tiny bumps?