Perennials susceptible to verticillium wilt include: Aconitum (garden monkshood, helmet flower), Antirrhinum (snapdragon), Aster (aster), Chrysanthemum (mums, shasta daisy), Coreopsis, Dahlia, Delphinium (larkspur), Dicentra (bleeding heart), Impatiens (balsam), Paeonia (peony), Papaver (poppy), and Phlox.
The plant symptoms that result when this disease attacks may be confused with seasonal die-back of foliage and with other plant problems such as fusarium wilt, bacterial wilt, root rots as well as drought and damage due to excessive soil moisture.
Plants may be infected for awhile before symtoms become visible. Initially plants wilt. Wilting tissue soon begins to yellow then turn brown and die. Internal discoloration or streaking of the sapwood occurs in most plants.
Both of these Verticillium species attack a wide range of plants besides herbaceous plants. Verticilium albo-atrum is adapted for the cooler soils in the world so is not usually found in tropical soils. Verticillium dahlia is more commonly found in most soils around the world. Even though V. albo-atrum is not as common as V. dahlia, it is more likely to be fatal to most plants.
These two Verticillium species are root invaders. They do not live in the soil as saprophytic fungi but can survive in the soil for several years as specialized "structures". Infected dead root systems improve the survival of these fungi in the soil. These fungi are often moved with infected soil or plants. They invade stressed roots. Plants that are blooming or seeding tend to be more susceptible.
Try to avoid stressing plants, especially their roots. Maintain/provide proper moisture and soil drainage. Avoid high nitrogen fertilizers - use balanced fertilizers or fertilizers with slightly higher phosphorus levels. Avoid deep cultivation around plants while they are growing. Avoid using herbicides if possible. If herbicides are used - spot treat (treat individual weeds very carefully). Remove infected plants and as much of the infected root system as soon as posible. Destroy the infected plants by burning or aerobic composting. Buy resistant plants whenever possible.