What is the white coating on my cotoneaster shrub?

The white coating is caused by an insect called scurfy scale and it feeds by sucking sap from your plant. Apply one or two applications of dormant oil in the fall or spring to control. (after and before leaf drop) With severe problems cut down the whole area and allow to grow again.

The new growth on my Manchurian/Black Ash is distorting and curling.

Caused by an insect related to aphids. Eggs in early spring hatch and the insect migrates to the new leaves to start feeding. Spray with insecticide soap and apply dormant oil in the fall and spring.

The leaves of my green ash are curling up in a cone shape.

Caused by the Ash Leaf Cone Caterpillar. Spray with Malathion or Trounce when they are exposed. Spraying when they are rolled up in the leave will not have any effect. Damage caused by the Caterpillar is only aesthetic.

In a dry fall how do I know I have watered by plants enough to prevent winter damage?

Check them once a week by poking down into the soil to check the moisture of the soil. If the soil is dry water in slowly with a soaker hose. Continue to check weekly until the ground freezes

What trees or shrubs should not be pruned in the spring?

Birch, Maple and spring flowering trees/shrubs should not be pruned in the spring. Prune Birch and Maple trees after the leaves have fully formed and no later than the end of June. Spring flowering trees and shrubs should be pruned after they are done flowering.