Stagnospora curtisii

Den Wilson
Mon, 17 Mar 2003 23:47:18 PST
Mary Sue,

I've never seen Stagnospora curtisii on Nerine even when grown close to
other infected Amaryllids. The problem with this disease seems to be rapid
re-infection by airborne spores so 'curing' a plant is very much a temporary
thing. The answer (if there is one) probably lies in regular protective
sprays and avoiding the cool/damp conditions the spores require for
germination. This is much easier said than done but ventilating the plants
whenever possible and not watering in cool/damp weather helps. In common with other persistant fungal diseases (rust, black-spot etc.) It is extremely difficult to eradicate once established and most commercial preparations rely on prevention rather than cure. The sad truth is that if you grow a number of different hippeastrum you will always encounter this disease sooner or later (usually sooner). It is possible to clean dormant bulbs in early spring by using a 1-hour dip in dilute bleach, hydrogen-peroxide or Dettol which will kill dormant spores under the tunic and in the neck of the bulb but relief is temporary because re-infection by airborne spores is usually not far away. The much hybridized H. vittatum appears to be a major host to this disease. On the other hand, some species appear to be very resistant or immune so perhaps the hybridists should concentrate on these. H. solandriflorum is just showing its first flower spike here and I've never seen a trace of Stagnospora on this species. H. puniceum and others also seem to be highly resistant. I would suspect that the more recent H. cybister hybrids are also worth growing.

Den Wilson
Isle of Wight
Zone 8 (maritime) almost frost-free.


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