I came across this article for Tu B'Shvat at the Jerusalem Post. It has good advice for the holiday and general common sense as well. Excerpts below, full article can be found here.

With Tu Bishvat around the corner, parents are advised not to give nuts or seeds, both traditional holiday foods and both of which pose a choking hazard, to children under five. With an undeveloped swallowing reflex, small bits of hard foods can slip into the trachea instead of the esophagus, says Dr. Oded Poznanski, a senior emergency department physician at the Schneider Children's Medical Center of Israel.

In addition, dried and fresh fruits should be cut lengthwise so they do not block breathing if they get stuck in the trachea. Large seeds and pits should be removed from fruit before it is given to preschool-age children....

Dried fruits are full of sugar and very fattening, says Schneider clinical dietitian Dana Resnick, and nuts - while healthful - are full of fat. It is best to eat them without sugar and not roasted to preserve their nutritional value, she said.