"Dennis Edward" wrote:

For the most part, people say you can use leaves in compost. But I've
heard there are some tree droppings you should avoid putting in compost.
Anyone know which ones?

You may want to avoid composting:

Rhubarb leaves (oxalic acid)
Oak (leaves are rich in nitrogen but slow to decompose.)
Spruce and Pine needles (high in acid and resin, slow to decompose)

Each of these has special problems. Some tend to kill the bacteria that
do the composting. A skilled, patient composter will have no problem.

Black Walnut shells (juglone - herbicidal toxins)*
Black Walnut leaves (juglone - herbicidal toxins)*
Weeds with mature seeds*
Diseased or insect infested plants*
Crabgrass*
Ivy*
Poison Oak and Poison Ivy*

*These materials should not be used in gardens unless they are
completely composted. Once composted, none of these materials pose any
problems.

Shinny leaves like laurel, holly, and rhododendron are slower to
decompose and compost better if chopped first.
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