I am in a panic. I've grown the bush plant before and they performed beautifully. I have one that I bought about a week ago. Some of the leaves are turning yellow, but more ominously, others are getting black areas on them. It is obviously sick. I just removed all the diseased leaves and moved it into a very sunny location. I suspect the yellowing is due to overwatering (it's in a container). I don't believe in folk remedies such as sprays containing baking soda and the like. Should I invest in a fungicide and try spraying it, or just discard it? It has lost about 20 to 25 % of its foliage due to whatever is happening to it.
DP
bush allamanda in trouble
The black could be a fungus from overwatering too. I would get it out of the sun, if it wasn't in the sun before moving it out into the sun could stress it anyway even if everything else was perfect, and when it's already under stress from something else, it's best to remove as many other possible sources of stress as you can. So a shady location (or at least protected from hot PM sun and getting no more sun than it was before you moved it) would probably be best until it recovers a bit. If you haven't already, I'd pop it out of the container gently and see how wet the soil is, if it's pretty wet then you might consider gently shaking off as much as possible and repotting it in some fresh potting mix (and if there are any brown mushy roots, I'd remove those too). Plants can absolutely come back from some defoliation caused by overwatering so I see no reason to discard it as long as you're willing to give it a little extra TLC for a while.
DP, can you post a picture of the symptomatic leaves?
dp I had the same problem with one of my allamandas last year and I thought the same thing--did I overwater, but allamandas don't like to dry out completely so I wasn't for sure. Mine was in the ground when this occurred. I just tried to reduce the water and I trimmed a lot of the diseased branches off. I debated on tossing it, but it slowly recovered (it took awhile) and is doing blooming this season.
Fauna4flora, here is a photo of sick leaves from the allamanda, and another to follow. The plant is in isolation and drying out, but it is still throwing leaves. I guess it has 50% of the original leaves left.
and here is the other photo
DP
I don't see any signs of foliar fungal infection or foliar bacterial infection. That does not rule out a fungal root pathogen, but my instinct is to go with jsut moisture stress and ditto Ecrane's advice. It may have gotten waterlogged without getting diseased. If you are interested in keeping a general fungicide around for when things like this pop up, I could try and see what's available to you, but otherwise the cost of a bottle of something is often more than the cost of replacing the plant. Pop the plant out of the container and inspect the roots- black brown or mushy or white fibrous and intact?
The plant is still in isolation. However, no more leaves have gotten sick. It was beginning to wilt this morning, so I watered it good. By late afternoon it looks fine. I didn't inspect the roots, but will if a post-mortem is necessary. Thanks a bunch to fauna4flora, phughes and ecrane3.
DP