Question
Our 40+ year old pink dogwood has only two petals rather than four. I noticed that last year two of the petals were smaller than the other two. Is this a sign of disease or stress or?

Answer
Sounds like it needs a little fertilizer. use a fertilizer like  Camellia-Rhododendron food,
acid based fertilizer, right after they bloom.  Or you can use 0-10-10 fertilizer in early to mid-Summer to help induce flower bud formation. The problem is the nitrogen use a fertilizer that is low in nitrogen. Normal lawn fertilizers are high in nitrogen and the tree maybe getting too much nitrogen from the lawn fertilizer. Broad cast the fertilizer around the tree under the foliage and water in. Use 1 cup per inch of tree diameter.