VERTICILLIUM WILT is sometimes called MAPLE WILT, because it is commonly seen in maples. However, it occurs in many common trees including redbud, Japanese maple, elms, ashes, etc.
Below is an excerpt of an article entitled Verticillium Wilt Refresher from the Michigan State University Extension:
Symptoms of verticillium wilt can be confusing because they are so variable. They include marginal scorch and complete wilting of leaves on individual branches in the crowns of potential hosts. Symptoms can occur at any time of the year but often show up when hot, dry weather begins.
Sometimes a single branch or the foliage on one side of a tree will die. Trees can go through years where no symptoms are present and then the symptoms show up again several years later. Some trees can struggle along for years, while others may die soon after symptoms appear. In addition to wilting, other symptoms may include: small leaves, stunting shoot growth, poor radial growth, sparse foliage and abnormally large seed crops.
There are many other factors that can cause leaf wilt and branch dieback. In general, adverse site conditions and environmental stress such as girdling root injury, drought, flooding, compaction, deicing salts or gas leaks can cause symptoms similar to verticillium. In addition, canker-causing fungi that grow through the bark and cambium to almost girdle a branch can cause wilting. Bark beetles, wood boring insects or sapsuckers can attack selected branches in a tree and cause enough girdling to result in branch failure as well. The question of whether the cause is verticillium or something else is best answered by having the sample tested.
There is no fungicide treatment available to control verticillium wilt. However, some other measures may be taken to prolong the life and to improve the aesthetic value of an infected tree. Management of this disease includes proper pruning, watering and fertilizing. If so little of the crown is affected that branch removal will still leave an acceptable specimen then prune symptomatic branches back to their junction with the next largest asymptomatic branch. Severely infected trees, which would be unacceptable as landscape specimens after symptomatic branches are pruned, might just as well be removed completely.
Water during dry periods, especially if they occur in summer or fall. Fertilize if needed with a low nitrogen, high potassium fertilizer. Excessive fertilization apparently increases problems with this disease.
Do not replant in the same site with a verticillum-susceptible species because the fungus can survive in the soil for years. Instead, choose resistant or immune trees such as birch, ginkgo, sweetgum, mulberry, willow, hornbeam, hawthorn, honeylocust, crabapple, London plane, oak or mountain ash. Also, where maples are desired, be aware that red and sugar maples are more resistant than silver or Norway maples. Of the Norway maples, ‘Jade Glen’ and ‘Parkway’ have shown more resistance than other cultivars of the species.
There is no guaranteed way to get rid of the fungus once the soil has been colonized. Where the disease has been confirmed and the tree has been killed, replacement with a verticillium-resistant tree may be the only feasible option.
We have had some apparent success using trunk injected phosphite, which has some nutritional and fungicidal properties. Otherwise, the general suggestions above are all we have to offer.