By Jim McCausland, Sunset Magazine

A dozen years ago I planted a Japanese maple by my front door,  dearly hoping it would never get verticillium wilt, which is to maples what the black plague is to people. 

 But three years ago leaves on a few branches on one side of the tree started to wilt. Then branches started to die back, and when I cut them out a telltale dark stain showed in the wood. Eventually the bark on the trunk split, and it became clear that I’d have to remove the tree. How sad.

The disease that savaged my tree is most likely verticillium or maple wilt. This fungus lives in the soil, then enters the tree through its roots, and eventually clogs the xylem (the vascular system that carries nutrients and water up into the tree), where it releases cell-killing toxins. When enough xylem is infected, branches die. When the xylem around most of the trunk is infected, the tree dies. There is no cure, though sometimes well-cared-for trees wall off the disease and outgrow it. And once verticillium is in your soil, it stays for a dozen years or more, so you can’t replace your lost tree with another susceptible variety.

So where do I go from here? I'm sending a slice of the wood to Jenny Glass, who diagnoses plant evils for Washington State University. If she says it's wood rot from an injury, then I can put another maple back after I dig out this one's stump. But if she confirms that it's verticillium, then I have to avoid replanting with susceptible trees, and only plant resistant or immune trees. I'll base my decision on the following three lists.

Here are common susceptible trees—those I can’t plant in verticillium-infected soil: most maples (Acer), horsechestnut (Aesculus), tree of heaven (Ailanthus altissima), silk tree (Albizia), Catalpa, carob (Ceratonia), redbud (Cercis), fringe tree (Chionanthus), camphor (Cinnamomum), yellow wood (Cladrastis), smoke tree (Cotinus), carrot wood (Cupaniopsis), quince (Cydonia oblonga), persimmon (Diospyros), Russian olive (Elaeagnus angustifolia), ash (Fraxinus), flannel bush (Fremontodendron), Kentucky coffee tree (Gymnocladus), walnut (Juglans), goldenrain tree (Koelreuteria), tulip tree (Liriodendron), most magnolias, sour gum (Nyssa), olive (Olea), avocado (Persea), pistachio (Pistacia), Prunus (cherry, plum, apricot, peach), pin oak (Quercus palustris), locust (Robinia), elderberry (Sambucus), Sassafras, pepper (Schinus), Sophora (Chinese scholar tree, Japanese pagoda tree, mescal bean), lilac (Syringa), elm (Ulmus), and Viburnum.

Here are those that can be either resistant or susceptible, depending upon cultivar and strain of verticillium: serviceberry (Amelanchier), dogwood (Cornus), poplar (Populus), and linden (Tilia).

And here are ones that are resistant or immune to verticillium: native maples (Acer circinatum, Acer macrophyllum), most red maples (Acer rubrum), manzanita (Arctostaphylos), birch (Betula), boxwood (Buxus), hornbeam (Carpinus), pecan (Carya), chestnut (Castanea), Ceanothus, hackberry (Celtis), katsura tree (Cercidiphyllum), citrus, conifers, hazelnuts (Corylus), hawthorn (Crataegus), dove tree (Davidia), eucalyptus, beech (Fagus), fig (Ficus), ginkgo, honeylocust (Gleditsia), witch hazel (Hamamelis), holly (Ilex), walnut (Juglans), sweet gum (Liquidambar), Magnolia kobus, apple (Malus), mulberry (Morus), oleander (Nerium oleander), Parrotia, sycamore (Platanus), firethorn (Pyracantha), pear (Pyrus), white oak (Quercus alba), southern red oak (Quercus falcata), willow oak (Quercus phellos), southern live oak (Quercus virginiana), willow (Salix), mountain ash (Sorbus), Stewartia, Styrax, California bay laurel (Umbellularia californica), and Zelkova.

You can find online information about most of these on Sunset's Plant Finder.