AboutJohn Cawly Expertise I can help with identification and possible treatment of plant diseases that affect houseplants and horticultural species, to include both biological (fungal, bacterial, viral, parasitic etc.) and environmental/cultural (watering, potting media, etc.) aspects.
Experience Practical experience with a wide variety of houseplants and greenhouse plants, including cacti, euphorbia, african violets, amaryllus, and many others.
Organizations American Phytopathology Society
American Society of Plant Biologists
American Society for Virology
Publications Molecular Plant Microbe Interactions
Proceedings of the National Academy of Science (in print)
Rhodora -- Journal of the New England Botanical Society
Allelopathy Journal
Education/Credentials BS, Southern Illinois University - Biological Sciences MS, Southern Illinois University -- Biological Sciences - Genetic Engineering Specialization PhD, University of Missouri Columbia -- Plant Microbiology and Pathology (Viral Diseases specialization/Biotechnology Emphasis)
Question Hello, I hope you can help me. I've recently bought a small example of the
above plant, and it was in need of repotting. It initially seemed very happy
and healthy but now the leaves are turing black and curling up, along with
the stems.
It isn't over or under-watered, and it kept in a full sun position. I have taken
to bringing it in overnight as it is obviously unwell, and I wouldn't want a
frost to finish it off, even though I know they are hardy.
I would be so grateful if you could suggest any possible causes.
Many thanks and best wishes
Lorna
London
UK
Answer Hi Lorna,
First, I must admit that I am very envious of Londoners and their relatively mild weather. Here in the midwest of the US, we are still in the throws of winter, and today has been our first day above freezing in a long spell.
I do not really know a great deal about this species, but I did some research through the databases to which I have access. There are two fungal species that may produce the symptoms that you describe. One is an Alternaria species (causing black stem rot) and the other is a Pleospora species. Each of these may cause a black leaf or black stem. Now, I am not confident that either of these is responsible for your sick plant, but those are two options. Both of these can be found in common soil, so if you potted with a soil-based mix rather than a peat-based compost, the fungal spores may have been present in the mix.
Consult your local garden centre for specifics about fungicide applications on this species. Generally in fungal infestations, there are dusts of sulfur or other general fungicides that may be applied. When the weather is reliably warm, place the plant in bright sun gradually.
If you have photos, I would gladly take a lot at them. You may send them to me at:
