White bugs on dogwood leaves
The white material on the dogwood leaves are the egg sacs of insects called cottony scale. The insect is the small brown spot at the end of the white mass. It died after it deposited the egg-filled sac.
Scale insects suck the plant fluid. High populations can weaken the tree. So, minimize their activity by getting rid of the insects and their egg sacs when you see them.
Depending on just how small your tree is, you might try wiping off all the scale and egg sacs that you see. (Garden gloves will decrease the ick factor!) Then, you might follow-up by spraying insecticidal soap, according to label directions.
Insecticidal soap is available under various brand names. All are considered organic. And every garden center sells at least one brand.
One caution if you intend to spray: Never apply any spray if the temperatures is, or will be, 80F or higher.
Thank you for your fast reply! I will start wiping them off, then wait for the upcoming heat to subside before I apply the insecticide.