Answer: Verticillium wilt is caused by a fungi which attacks the vascular systems of plants. The wilt fungi remains in the soil if there are suitable hosts. Plant debris and some commonly encountered organic matter can sustain the life of the fungal spores until another suitable host is planted in the same soil.
One way to discourage the pathogen is to rotate plants in the garden bed. Begonias are susceptible to verticillium and probably should not be planted in the bed this year. You can reduce pathogen populations by not planting anything in the bed this year, effectively starving out the majority of the disease causing spores.
There are some resistant plant varieties which can be planted in the affected beds (look for specific resistance to Verticillium on the seed package).
Hope this clarifies things for you!
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