-- Oak decline affects mainly red oaks, over broad forest areas of the
eastern United States. Damage varies by site condition, forest type,
region, and year. Hickory species may also be affected when on sites
with affected oak.
the Agents. -- Environmental, stand, and site factors usually are
involved at first. Various insects and pathogens are involved in later
Injury. -- Oak decline usually affects mature overstory trees and
is typified by a gradual but progressive dieback of the crown (figure
61), reduced growth, and tree death after several years.
-- Oak decline involves complex interactions between environmental and
biological stresses and subsequent attacks by secondary pests. Predisposing
factors, such as genetic potential, climatic factors, or old age, can
set the stage for damage by some other injury. Drought, insect defoliation,
unseasonable freezes, root damage, or extended flooding can incite active
decline. Contributing factors, such as pathogens (e.g., Armillaria root
rot, page 47), insects (e.g., twolined chestnut borer, page 20), or
both, (figure 62) can kill trees.
-- Harvest oak stands before they become overmature. Promote advanced
reproduction in young and middle-aged stands to ensure regeneration
at harvest. Removing dead and declining oaks to utilize trees before
they degrade. (Note: none of these actions will correct conditions leading