One of the worse combination of stresses on landscape plants and turf is a very wet spring followed by a drought in summer. The following is an article on the subject.
Drought Stress after a Wet Spring
A month ago we were very wet in many areas. Now, we are starting into drought stress conditions in parts of the state (as is common in DE summers). This combination of wet-dry can be extremely damaging to landscape plants and turf. In periods of excess moisture when soils are saturated, root growth often ceases due to lack of oxygen and some roots will die. There can also be increased incidence of root rots. Upon onset of hot, dry weather, plants with weakened root systems often will wilt prematurely and will have more severe stress. In addition, planting activities done in wet soils often creates added compaction and as soils dry out, plants will have a difficult time to root out. Cool season turf growth in cool wet springs is often excessive, especially with heavy spring nitrogen fertilizer. Turf in these conditions will increase shoot growth at the expense of root growth and will also deplete energy reserves. With the return of dry weather, this turf will undergo excessive stress. Trees and shrubs that experienced root damage in wet soils this spring will have additional stresses put on them during drought periods this summer. We are seeing premature leaf drop in many trees and shrubs at this time because of this double set of stresses (wet to dry).
Gordon Johnson, Extension Agriculture Agent, UD, Kent County