I’ve had 2 die in the last couple of weeks. One for no particularly apparent reason – it was my main plant that I put my caterpillars on. It had bits that looked unhealthy for a while and then I gave it some fertiliser and it came back and then couple weeks later it just died completely almost overnight. The other one was the first plant in the garden to get aphids on it – I think it may have got overloaded with aphids before the parasitic wasp and the ladybirds arrived. My garden is under siege from aphids, far more than last year possibly due to the extra heat. Ladybirds are only just starting to build up and the parasitic wasp is struggling to keep up with the reproduction rate. Normally what happens for me is the aphid population rises about this time and then the parasitic wasp and ladybirds take over. But that’s taking a bit longer this year – hope I don’t lose any more plants!
Wow! Just had a phone call from a man in Tauranga who is concerned about this – I wonder if anyone else is experiencing this – I’d forgotten I posted this six or something years ago, but it’s EXACTLY what is happening to my swan plants this year.
Has anyone found a solution to this? I’m going away today and was hoping that things might have “righted” themselves when I come back. The aphids have really taken over, the swan plants are wilting and dying… Fortunately only in one section of the garden.
Thank you all for the help and information. I don’t think that it is over watering or too much fertiliser. I only applied the fertiliser after a lot had died. Hoping that lack of fert may have been the cause. But I have now sprayed the remaining plants with “guardall” and to date – no more have died. Maybe as you say Jacqui its something that isn’t visible to the naked eye. And yes the stems are very hollow and black looking on the inside. No “guts’ to the stalks at all.
But thank you all anyway.
Have you considered overwatering? It is quite common for potted plants indoors and in green/hothouses to have too much water during winter when the plants are not active. It used to be one of my faults, giving the potted plants in the butterfly house too much water, which the roots dislike. Because the mix at the top was dry I watered them, only to find them eventually dying, and when tipping out the pot found the plant had wet feet, which many plants cannot tolerate. I purchased a moisture meter and the problem was solved.
Strange coincidence, today I have been reading about phytoplasma diseases and how they can affect milkweed in the USA. I was wondering if that happens here… I don’t know enough about it, but it would be worth investigating I think.
Wikipedia says: Phytoplasma are specialised bacteria that are obligate parasites of plant phloem tissue and transmitting insects (vectors). They were first discovered by scientists in 1967 and were named mycoplasma-like organisms or MLOs.[1] They cannot be cultured in vitro in cell-free media. They are characterised by their lack of a cell wall, a pleiomorphic or filamentous shape, normally with a diameter less than 1 micrometer, and their very small genomes.
Phytoplasmas are pathogens of agriculturally-important plants, including coconut, sugarcane, and sandalwood, causing a wide variety of symptoms that range from mild yellowing to death of infected plants. They are most prevalent in tropical and sub-tropical regions of the world. Phytoplasmas require a vector to be transmitted from plant to plant, and this normally takes the form of sap-sucking insects such as leaf hoppers, in which they are also able to survive and replicate.
So what that means in simple terms is there’s a “thing” that can’t be seen but which could be spread by insects and that it affects the inside of plants to such an extent that it can kill plants.
As I say, I don’t know enough about phytoplasmas but I wonder if this could be affecting swan plants. Thoughts anyone?
I’m wondering if you overdosed them with fertilizer? I find it difficult to get my swan plants in pots through the winter. I am in Wellington.
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