What is happening to my monopodial plants? New leaves drying out.
 

Hello all,

On a few of my plants, an Angraecum didieri (1st photo), a Fenanthera monachica (2nd), and a prized Vanda falcata (3rd+rest), the newest leaves have dried out. Why is the happening and how do I stop it?

On the Vanda, I also posted some pictures of dried leaves that fell out. They are green at the bottom. I *may* have stupidly tugged at them lightly to see if they were still attached. I am worried they took the meristem with them and those growths are ruined. Even on the leaves that have not fallen out, I am worried the meristem is dying/has died. I am also worried about this on behalf of the Renanthera.

The V. (Neof) falcata looks OK. There are multiple growths. . the Renanthera doesn't look good. Angraecum didieri tends to make new growths. The pattern is troubling, though. What are your conditions? (Light, temperature). How about watering? Has anything changed?

I think the Angraecum has become pretty stable so it should be all right and continue to make new leaves. Unfortunately, on the falcata, while the picture does not show it, virtually every growth has had this drying out happen to the newest leaf. I do also have multiple growths on the Renanthera but same problem on 2/3 of them though that is the sickest plant. Weirdly, while the Renanthera and Angraecum had this problem for a while, it basically happened overnight to the Vanda.

I have been watering them usually around once a week. I have been very neglectful about fertilizer, however. It has also been pretty warm until recently. Most days in August and early September were above 90f. Now it is low 70s in the day and 50s at night. They are outside on a table under an umbrella. That said, my big Angraecum veitchii managed to get pretty badly sunburned on that same table.

This problem actually started months ago in the winter with a different set of plants, one of which died. The others stabilized. It seems to be accelerating.

I also have an ongoing scale infestation but it seems to be confined to the Cattleyas for the most part. I have also been spraying with captan, malathion, and thiomyl since the scale and weird “dry rots” started. It has not gotten better. I’m worried I have now lost the crown/active growing parts of the Renanthera and the Vanda. I hope that is not what the green parts of the leaves that fell of the Vanda were.

I'd be curious to know what's going on with the Neofinetia, because I have the same thing happening to mine occasionally and it seems like a really random occurance. I have never paid attention if the meristem is dead after that.

Once-a-week watering sounds like not enough, especially when it is hot. I am watering pretty much every day in similar temperatures. (Even the ones in the greenhouse which is quite humid but does tend to dry out by late afternoon). If your environment (like a grow tent) so so humid that things don't dry out, then air-movement likely to be inadequate. Vandaceous orchids all need a lot of air around roots, so that frequent watering and some drying in between is what they need. Monopodial orchids don't have any storage mechanism (like pseudobulbs) . When too dry, they do things like losing leaves to reduce transpiration in the "drought".

Thank you all for the replies.

They have been outside in my yard completely in open air. I think the air circulation might be okay then. They probably did need more water. I should mention though that if it rained, they also got watered in addition to my regular scheduled watering. It is New York so it rains a fair amount. Maybe they did not get the benefit of this because they were slightly under an awning though. I think I might be able to save the renanthera as it has a keiki. I definitely need to fix my fertilizer and scale problems though.[COLOR="Silver"]


Edit: I have also been watering the Renanthera a few extra times for the past month or so.

First, scale is always bad news... and you'll have to be persistent to get it under control. While things are still outside, a good time to treat with the chemical pesticides that you likely won't want in the house if that's where they'll go i winter. (GH, keep on treating... GH is a petri dish)

If the weather went from hot to chilly quickly, also a challenge. I hope you are doing your watering in the morning... when the nights get into the 50's F you don't want them wet - cold and wet is an invitation for rots. A bit of toasting will leave you with ugly leaves but the Angraecum Veitchii should still be fine. Dealing with sun, as it moves through the seasons, is a challenge that for me took several years to get right. Definitely requires a lot of vigilance.

#1 and #3 look like not enough watering. If there is plenty of air at the roots you can water Angraecums and Neofinetias every day during warm weather. Once a week isn't enough. BUT! Your weather is changing. Neos don't do well cool and damp.

#2 looks like residual damage from bugs.