Control PLANT DISEASES
For Better Farming And Better Living

Mimeo BP 2-8
January 1958

Maple Wilt

Wilt is one of the most destructive diseases of maple and has been re-
sponsible for the death of many fine trees in several Indiana cities. Wilt
is caused by the fungus Verticillium albo-atrum which is a soil borne mold
that causes a vascular disease.
Wilt caused by this fungus attacks all species of maple and is also
known to affect black locust, catalpa, elm, flowering almond, ailanthus,
Kentucky coffee tree, Japanese barberry, linden, privet, redbud, smoke tree,
sumac, tulip tree, viburnum and yellow wood.
The first symptom of wilt is the sudden, wilting or flagging of scattered
branches during late June, July or August. In some cases, whole sections of
the tree will wilt.
Trees showing only a few wilted branches may sometimes appear to recover
and not wilt in succeeding years. Generally, once wilt appears in a tree
it will gradually spread until the tree ultimately dies. One of the typical
symptoms of maple wilt is the production of fine green streaks in the young
sapwood of wilting branches. This symptom usually occurs in the sapwood of
the current seasons growth and frequently at some distance from visibly
wilted twigs or branches. In other tree species the young sapwood of wilted
branches will have noticeable brown to yellowish brown streaks. Usually the
foliage of infected trees turns yellow or brown and leaf drop may occur.
The Verticillium wilt fungus lives in the soil and invades susceptible
trees through the roots. For this reason the streaking of the sapwood de-
scribed above may extend from the roots into the main trunk and branches. It
is usually advisable to examine the basal portions of wilting branches for
the typical grass-green sapwood streaks as they frequently may not extend to
the tips of wilted branches.
Once a tree is suspected of being infected with Verticillium wilt, all
dead branches or branches shewing wilt should be removed. Wilted branches
should be cut off some distance below the visibly wilted portion. Usually
it is not advisable to remove live branches immediately since many branches
that show wilt may not die but often produce a new crop of leaves 3-4 weeks
after wilt first appears or they may leaf out normally again the following
spring. Pruning out dead branches will not eliminate the wilt fungus if it
has invaded the trunk and roots of affected trees.
Trees suspected to be infected with wilt should be fertilized in April
using any good complete fertilizer mixture. Maples and other trees infected
with wilt may sometimes be sufficiently stimulated by fertilizing that they

PURDUE UNIVERSITY Agricultural Extension Service, Lafayette, Indiana
Department of Botany and Plant Pathology, Life Science Building