mmarteen wrote:
My houseplants (amaryllis and various other tropicals) have all acquired a
yellow fungus (looks sort as if I sprinkled sulfer powder) on the the soil
around them. It could not be killed by cinnamon, what I usually use to
treat mild fungal problems. I have not been overwatering them, rather the
opposite, I have been letting them dry out until they droop and then
watering them. Any ideas what this is and how to kill it without killing the
plants? I was just about to put them outside with my annuals but will pitch
them rather than loose the lot if I can't get rid of it.

You have the dreaded Marphistes fungus, spread by the Marphistes aphid
which spreads the fungus by contact with its foot pads.

Go to your nearest fertilizer wholesaler and beg, buy or steal about a
kilogram of ammonium nitrate. Take it home and pile it in a large
baking dish. Mound it up and make a depression in the middle, just as
if you were going to add eggs and stuff to a cake mix. Pour about 1/2
cup of diesel fuel in the depression and start kneading. Continue to
add diesel fuel as needed to obtain a doughy mixture. Form your mixture
into a ball about the size of a small cantaloupe and set it in the sun
to dry. Be sure to poke a small hole in the ball, just large enough to
hold a small firecracker or blasting cap for an igniter.

When your ball is dry, insert a firecracker or blasting cap into the
small hole. Use a dab of spackle, putty or other similar substance to
hold the igniter in place and to fill any voids. Light the fuse of your
igniter and you will see results almost immediately.