I'm finding a couple references to calcium deficiency; here is one
http://www.ars.usda.gov/SP2Use...[Summary].pdf
Calcium (Ca) deficiency: Initially, brown spots occurred
on the distal tips of upper leaves. As the disorder
progressed, the spots became larger, young flower buds
became brown and aborted, and large flower buds
abscised. Affected leaves then developed a purple-brownish
coloration.
