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.
If you notice the leaves on your grapefruit (Citrus paradisi) tree turning yellow, don't panic. There are many causes for this, from the serious to the mundane. Like a doctor, an examination of the grapefruit tree will help you make a correct diagnosis and choose the right treatment. Grapefruit trees grow in U.S. Department of Agriculture plant hardiness zones 9 through 11.