lost a maple tree to verticillium wilt last year. I would like to
plant another tree in that area, but am concerned because I
understand the disease persists in the soil for many years. Are
there any trees I can plant there that would be safe from
wilt is a fungal disease that affects many deciduous trees and
shrubs, as well as herbaceous ornamentals and certain vegetables.
Conifers appear to be resistant.
The fungus stays dormant in the soil until it enters a susceptible
plant through wounds in the roots or base of the tree. It clogs the
water conducting vessels in the infected plant, reducing the flow of
water to branches and leaves.
Symptoms of verticillium wilt include heavy seed production,
smaller than normal leaves, browning on the margins of the leaves,
and branch dieback. It is not uncommon for one side of an infected
tree to be wilting or dead while other side appears to be healthy.
Another common symptom is the discoloration of the wood under bark
of wilting branches. Healthy sapwood is white. If it is infected
with verticillium, the sapwood may have dark green, black or
reddish-brown streaks. The color of these streaks depends on the
species of tree. Newly infected or small branches may not exhibit
Dogwoods are resistant to Verticillium Wilt
Large trees can
live for a long time with the infection, but most trees die in two
or three years. The management of mildly infected trees includes
protecting them from road salt and drought stress, and a moderate
fertilization program that avoids high nitrogen applications.
Research into fungicide injections has shown that some populations
of verticillium fungi are more susceptible to control than others.
Avoid using wood chips from verticillium-infected trees as
mulch or in potting mixes because the fungus can survive mix and
infect other plants that are mulched with them or planted into the
Planting resistant species where verticillium wilt has been a
problem is the best way to deal with this disease. Species that have
shown resistance include: beech (Fagus spp.), birch (Betula spp.),
boxwood (Buxus spp.), hickory (Carya spp.), katsura tree (Cercidiphyllum
japonicum), hornbeam (Carpinus spp.), dogwood (Cornus spp.),
hawthorn (Crataegus spp.), ginkgo (Ginkgo), honey locust (Gleditsia
triacanthos var. inermis), holly (Ilex spp.), larch (Larix spp.),
sweetgum (Liquidambar styraciflua), crabapple (Malus spp.), sycamore
(Platanus spp.), white oak (Quercus alba), pear (Pyrus spp.), and
walnut (Juglans spp.).