Mildew

Mildew on Sinningia richii

In 2007, I had problems with mildew on my sinningias for the first time.  It started on Sinningia richii, and some time later spread to other soft-green-leaved plants of the corytholoma clade, namely S. defoliata, S. araneosa, and S. nordestina x araneosa.  Plants of other leaf types and other clades were not attacked until, eventually, some mildew appeared on S. hirsuta (sinningia clade).

Countermeasures

Vivian Scheans, on Gesneriphiles, recommended athlete's foot spray, and said not to use the powder.  I can confirm that the powder is a bad idea.  I tried it on Sinningia richii, and it destroyed the leaves.  I have not yet tried the spray.

What I have been doing is washing the leaves with soap and water.  This is pretty effective at getting rid of the mildew without further damaging the leaves, but is obviously impractical if a large number of leaves are affected.  It does have the advantage of safety.

I will probably try other things, eventually, and keep this page updated with the results.

[July 2009] So far, not much luck in the cure department.  Prevention is better, if you can manage it.