Alan wrote:

I've heard of people spraying baking soda / sodium bicarbonate to control
black spot on their roses. Has anyone here had any success with this. I did
a search of this group on google and found references to powdery midew but
not to blck spot so sorry if the question has been asked recently.

Alan


Did you use latin names and try google for the web. I'll make sure this
one goes in the archive;-)

Only a search for DIPLOCARPON ROSAE Sodium Bicorbonate on the web
brought up plenty for me.. Although some were *also* refs to the powdery
mildew.

The other thing to do is to use the Chemical symbol formula so you'd
search for:
DIPLOCARPON ROSAE NaHCO3

Although in this case google found that too specific (only 4 hits!)

The trick with blackspot seems to be addition of an oil and or potassium
bicarbonate. Neem oil is also mentioned.

The basis of most of these bicarbonate controls is that they upset the
pH balance enough to prevent the pest functioning.

Incidentally the mildew experiment is one I repeated at University.. My
results were inconclusive!-))

I found this site:
http://www.herts.ac.uk/natsci/Env/Fu...spot/home.html
Most interesting although out of date (2 years).. It only compounds my
feelings as an organic supporter NEVER to purchase cut flowers again!-)

Useful stuff sodium bicarb.. Its also used extensively by kidney
patients-)

//
Jim