Leaf Rust/Scale Question
I recently lost a N. ventricosa x sibuyanensis to what I think was scale. I wish I had taken photos before I chunked my three year old mother plant but I managed to save an offshoot that now has lots of growing room. Essentially the leaves became deformed and began to weep and eventually wilted.
I tried Natria Rose & Flower with a light diluted application. Ultimately I think this was a mistake and just expedited the plant's death.
In any case, this truncata was near, if not touching, the infected plant. Is this leaf rust or scale? I don't have much experience with pests/disease with my carnivorous collection.
Also, can anyone recommend a decent and hopefully damage-free solution?
Looks like either sunburn or cercospora to me.
Interesting. I'm inclined to think sunburn. With the time change and me preparing for spring I got a little zealous with reintroducing my collection back outside.
As for the raised little bumps, this is how I think the scale began on the other plant.
I included a side second shot.
I really appreciate the input.
it looks like sunburn to me.
Third vote for sunburn. Sometimes Neps will get brown spotting from cold weather below 40F or cold water below 40F applied to the leaves. If it hasn't gotten that cold for you lately then it probably needs more shading.
I can at least say for certain it is definitely not scale or scale damage. 100% sure.
Just FYI: Scales, even if they die, remain on the plant until you remove them. They will always come off when scratched at with a fingernail. So my test when I suspect them is to try and scratch the brown bumps off.
Good ID pic for future reference:
Edit: what I said above applies only for the first photo. I doubt you have scale in the second one but I'd need a closer pic. I can't make them out. Many Neps form raised green bumps on their leaves because they are extrafloral nectaries, secreting food for ants or whatever else likes it. Bicals come to mind for me here--they've got nectaries everywhere.
1) the plant looks sunburned, especially in the first photo - especially given the overly yellowed look of the lamina.
2) the "bumps" / spots on the underside of the leaf are almost certainly nectar glands, a normal leaf feature.
Given your description; "Essentially the leaves became deformed and began to weep and eventually wilted." I would guess that the plant's demise had nothing to do with an insect pest, but a cultural error that resulted in - for example - a catastrophic failure of (possibly) the root system. Even if you do get an infection of Cercospora (a fungus often - but erroneously - referred to as "Rust"), unless the plants are seriously stressed, the pathogen will not result in complete collapse of the plant as you described. The genus Nepenthes has evolved to co-exist with the Cercospora fungus in their habitat; many (if not most) jungle photos of the various species will depict plants clearly infected with the fungus, and yet they are perfectly happy and thriving. Cercospora is not something that generally results in serious health compromise, rather, it is more of a cosmetic problem....UNLESS your plant is severely stressed as a result of poor cultivation practices! (IE: low humidity, low light, poor soil ingredients, over/underwatering, inconsistent care, etc.)
As for Scale, that is a rather conspicuous insect that cannot easily be mistaken for anything other than Scale. The marks on the underside of the leaf you included are almost certainly NOT Scale. I suspect your problems were not an insect issue at all, but something awry with your cultivation techniques. You should always include as many details about your care regimen as possible when requesting diagnostic assistance, since its often a single overlooked detail that is responsible for the plant's failure to thrive, and not the presumed "insect problem" at all.
Addendum: I do not know if Nepenthes commonly succumb to bacterial infections (not something I have experienced) but your description of a plant that "began to weep and eventually wilted" is powerfully reminiscent of a bacterial affliction I saw a couple of times on Phalaenopsis in cultivation. A bacterial infection can basically consume the plant's soft tissues from the inside out, and one of the symptoms is foliage that breaks out in "bacterial sweat" that oozes out of the leaf surface. But as I say, I don't know for a fact if Nepenthes are subject to such a thing.
Last edited by Whimgrinder; 03-16-2014 at 05:55 PM.
This is great stuff. Thank you guys for the prompt and in-depth replies.
I really will have to look back at my care techniques to see what I may have done that went wrong. I think a combination of that plus our unusually variable winter this year was to blame.
In any case, I appreciate your responses and will just gradually reintroduce my collection back outside.
Side note: I'll have to start doing a bit more research on pests/diseases before it is something other than grower-error.
Good stuff there, Paul
Originally Posted by Whimgrinder
I've seen it often: something disastrous happens to a plant and the grower assumes insect pests are at fault, and so they haul out their best/favorite weapon against bugs. After further investigation, it turns out to be a cultivation problem, not an insect issue at all. I realize there is a powerful temptation to respond quickly to fix a problem, but doing good research before making hasty conclusions is the wiser thing to do -- as any experienced horticulturist will tell you ;-) (and I assure you, we've all made the same kinds of choices along the way to "horticultural wisdom"). If in doubt, seek counsel before choosing a course of action. The odds are you will discover something you didn't know that will guide you to a remedy.
Originally Posted by jgivs