Monnierara Millenium Magic 'Witchcraft' with brown areas on roots

[zane93nyc]

Hi, This is my first post and I'm hoping I can get some advice for possible root rot.

I got it last October in a 3 inch round pot. After blooming I allowed it stay dormant and then repotted with NZ tree fern fiber into a 4 inch square pot. I started watering on May 25th and the backbulbs plumped back up, but now the roots have brown areas that aren't looking too good. I feel that I may have overpotted. I removed the top layer of media to allow the roots to dry out better and moved the pot closer to a fan. Can I attempt to carefully repot back into a 3 inch pot?

I also noticed some spotting on the leaves in the crown and found a small, thin pest hiding which could be thrips. I flushed out the area with water and will try spraying with spinosad as soon as possible.

[Roberta]

First, Welcome!
I wouldn't worry about the spots on the roots. It should have been potted a bit deeper, but those roots will find the medium. Don't try to move it now. Do be on the lookout for pests - For Catasetinae, spider mites are the worst pest, they love thin-leaved plants.

[zane93nyc]

Thank you! I'll definitely watch and wait to see how it turns out.

[estación seca]

The brown areas might have picked up pigment from the tree fern fiber. If I read correctly, those roots were covered with fiber, and you exposed them? If so, I would re-cover them with more medium.

The clear spots on the leaves worry me. These plants are spider mite magnets. I would treat now for spider mites. Spray the entire plant including all leaf surfaces with 70% alcohol or an insecticidal soap solution. You can also keep spider mites under control by completely wetting all surfaces of the plant every week.

[zane93nyc]

Oh, that's a relief if it's just staining from the fiber. Thank you for your advice. I went ahead and covered up the roots again so they aren't exposed. And I'll start washing the foliage weekly to keep pests at bay.

[MateoinLosAngeles]

I don't see anything worrisome!

The browning is faint and can be some color picked up from tannins exuded by bark or tree fern fiber, as Estación mentioned. Keep in mind that this cultivar isn't black, but rather, a veeeery deep deep burgundy color that makes it look black. This suggests the plant might have high anthocyanin levels, providing red pigment. Even though anthocyanins are mostly concentrated in flowers and leaves, they can also show up on roots. I've noticed some of my deepest purple and bright red Cattleyas showing similar stains on the roots... mix green with red and you get brown...

The dots could be worrisome or not. I would invest in a good magnifier and a microscope, a $20-30 investment on Amazon. They really help.

On the one hand, minimal cell damage can be caused by changing conditions (from temperature to light) or even by hitting the plant at some point. It can also be caused by the guttation that is characteristic of early Catasetum growth, as it sucks in the water from the older pseudobulbs, those droplets can do some damage on the leaf leaving those tiny translucent dots behind. This happened to me on a Catasetum that had similar spots and no trace of pests.

On the other hand, it can, indeed, be spider mites. Spinosad's effect on spider mites is contentious; it shows some effect, but some research suggests spider mites are quick to become spinosad-resistant within two to three generations. Given that you can have a new generation every 7-15 days, the Spinosad treatment would stop working before the summer is over. What works very well with spider mites is knocking them out with strong jets of water (a shower head or hose works well). Insecticidal soap works well, and so does Organishield. The gold standard miticide is Azadirachtin, an active ingredient in Neem Oil. I find Neem Oil to be pretty harsh on orchids, but some products like Azamax contain Azadirachtin without Neem Oil's side effects. This active ingredient mostly works as an IGR (blocks the mite's ability to reproduce), so combining the treatment with a mechanical removal with either insecticidal soap or strong jets of water will give you the most complete protection/treatment.


Finally, Catasetum, especially Monnierara, responds very well to environmental humidity; spider mites tend to be attracted to dry air, so upping your humidity can help. Be very careful when spraying the plant with water at this stage, I've found that during the early season, the young Catasetum growth is extremely sensitive to rot, especially due to water logged in between the leaves. They become much more resilient in the late summer once the pseudobulb has fattened up. At this stage, air movement is crucial (I have a fan right on top of my Catasetum), especially if you're wetting the leaves. Catasetum grows high in the canopy and responds very well to air movement and high humidity but not so well to stagnant water, so be careful. The counterpoint of air movement is that it is one of the spreaders of spider mites, thus increasing air humidity and ensuring the air circulation doesn't hit other sensitive plants is important.

[zane93nyc]

Thanks so much for the reply. For an update, I'm relieved to see the roots are branching and growing deeper on the sides of the pot. I haven't noticed any pests after washing the foliage. I have a magnifying glass, but will look into getting a microscope. If I see the pests return, I will try alternating spinosad with neem or Azamax as well as an insecticidal soap.