Well, 18" is pretty short corn. If one of my corn plants only gets that
tall, it doesn't produce corn either. How tall is your variety of corn
supposed to get?
If radishes are planted too close together they often go to seed without
making an edible radish. (did you thin them?... or at least plant them
sparse enough that most aren't crowded?) The same happens if you grow
them during warm weather, even if not crowded. Have yours sprouted up to
produce flower buds or actual flowers? If so, it's to late. Plant more
if you still have a month of frost free weather.
Zucchini have both male and female flowers. Female flowers have a small
zucchini already formed at the base. Are you getting both kinds of
flowers? The first several flowers tend to be male only. If you are
definitely getting female flowers, go out in the morning and pick one of
the male flowers. Peel off the petals and use the remaining "paint
brush" to pollinate any open female flowers.

Steve ... in the Adirondacks where the gardening season is about done
anyway.

Kathy wrote:

Well I am really bummed. We have beautiful 18" high corn with tassles and no
ears of corn. Beautiful leaves on the radishes but no radish blubs under
ground. Gorgeous zuccinni vines and flowers but it never set on any
zuccinni. HELP please.

Kathy