- It is a soil borne pathogen.
- Don't bring in "fill dirt" to your garden/landscape
- Don't put pruners, saws, etc,, nor your bonsai (2B or 02B) on the ground
- bonsai on benches
- tools in your pocket, in your hand, or on elevated work surfaces
- Interestingly, verticillium is killed in the course of ordinary composting.
- Don't use stuff that hasn't been composted in your garden/landscape
Sanitize pruners, saws, etc., before use and after any cut of tissue that might be infected and especially a tool that you dropped on the ground.
Verticillium effectively doesn't grow when temp's are above 75F --> it is a spring-time disease.
Verticillium gets into the xylem (wood). Therefore, it
progresses upward from its entry point (direction of water flow). It will cause the stem it is in to suddenly die = leaves above suddenly wither, turn brown and dry AND remain attached to the tree (leaf drop is a life process).
Prune an affected branch below the entry point to remove the infection from the tree.
Verticillium appears as dark 'staining' in rings in cross-section in streaks if you split the stem.
IMHO, verticillium is rarely ever the problem. It has been hyped so much that every maple problem is labelled "
VERTICILLIUM!!"
In your circumstances, the most likely scenario is a maple in your landscape that you tossed some fill dirt around. Late in summer there are weeds growing around it. You take the weed whacker to them and also nick the bark, introducing verticillium from the (now) weedy fill. The tree continues doing well and does its colorful thing in fall. Next spring the buds pop and its looking beautiful with all its new foliage. And then, about Apr/May, the lowest leaves get droopy and then a few more above that the next day and etc., up the tree. Within a two or three weeks, they are all crispy brown and still hanging on the tree. Since it was nicked at the base of the trunk, there is no possibility of cutting off the infected stem = the tree is dead.