What you’ll see…is wilting leaves and dieback of branches, often one at a time or on one side of the tree. This can occur over a number of years, with remission symptoms in some years, or can rapidly progress to plant death in a year or two. Other symptoms of Verticillium wilt may include: marginal browning and scorching of leaves, abnormally large seed crops, small leaves, stunting, poor annual growth, and sparse foliage. Sometimes large areas of cambial tissue die from infections by the fungus and opportunistic fungi such as Nectria develop in elongated cankers. Late season infections may not be noticeable until plants come out of dormancy with branch dieback evident. Some of the most common trees and shrubs found with Verticillium Wilt damage are: Japanese Maples, Burning Bushes, Viburnum, Most Maple trees and Lilacs.
The reason for the problem…is caused by soil-borne fungi, Verticillium albo-atrum and Verticillium dahlia. However, Verticillium dahlia is the species that most commonly attacks woody ornamentals in the Oakland County, Michigan. Because of its ability to spread internally or systemically within the plant and to kill the plant, Verticillium wilt is considered a serious disease. Verticillium invades the root system directly or through wounds caused naturally by root growth through the soil or soil organisms. It is now being discovered that annual flowers create a higher incidence of Verticillium wilt infection when these plantings are installed near susceptible landscape plants. It has been suggested that some nurseries are unknowingly using infected soils to grow their annual flower flats. Once in plant tissues, the fungus produces toxins and invades the xylem (water conducting tissues), clogging it up. This robs stems and leaves of needed water and minerals. The fungus is returned to the soil as plant parts fall or die, and tiny resistant fungal microsclerotia are spread by wind, in soil and on equipment. Development of Verticillium wilt is favored by factors that stress roots, including wounding and droughty conditions.
You should… keep the tree growing with proper watering and maintenance.
- Avoid planting annual flowers within 6-10’ of susceptible trees and shrubs
- Remove dead and weakened branches. This does not remove the fungus from the tree, but prevents infection from other fungi. You must sterilize you pruners and saw blades with rubbing alcohol after caring for the infected tree so transmission of Verticillium fungi isn’t introduced to other plants.
- Destroy plant material and debris.
We can help by…Providing a sound organic tree fertilization program that includes a soil fungicide known as Companion. If caught early enough we can protect from further infections. Never before have we utilized real sustainable landscape solutions but as you would expect Contender’s Tree & Lawn Specialist’s, Inc. is on the cutting edge of landscape science.