Edit. After Black September's assassination of Israeli athletes at the Munich Olympics in 1972, Prime Minister Golda Meir okays a black-box operation to hunt down and kill all involved.
Yellow pollen is produced by evergreen trees, primarily pine trees, including spruce, true cedar trees, fir trees, larch and hemlock. Although yellow pollen looks like it could cause an allergic reaction, in reality it does not trigger allergy symptoms at all. It can stain the skin and clothing, however.
Elm phloem necrosis (elm yellows) is a disease of elm trees that is spread by leafhoppers or by root grafts. This very aggressive disease, with no known cure, occurs in the Eastern United States, southern Ontario in Canada, and Europe. It is caused by phytoplasmas which infect the phloem (inner bark) of the tree.