Presence of the pathogen in soil and proper environmental conditions, such as low pH levels and humidity, initiate the proliferation of clubroot in new plants. The fungus generally enters the plant through the roots, where it initiates the rapid growth of cells and causes the roots to swell with excess tissue. The impaired root system cannot efficiently absorb water or nutrients, leading to a weakening of other parts of the plant. If a plant harboring Plasmodiophora brassicae carries out its full life cycle, the roots eventually decompose and ultimately release more of the fungus into the surrounding soil.