Transportation of seeds (seed trade):

• The import and export of contaminated seeds lead to movement of pathogens from one country to another.
• Ex: Late blight of potato, Downy mildew of grapevine, Citrus canker, Fusarium wilt of banana, etc

Planting diseased seed materials:

Planting diseased bulbs, bulbils, corms, tubers, etc.  of vegetatively propagated plants such as potato,  banana, many ornamentals and fruit trees etc., help in dispersal of pathogens from field to field, locality to locality or from one country to another.

During adoption of normal farming practices:

Human beings engaged in preparatory cultivation, planting, irrigation, weeding, pruning etc., help in dispersal of plant pathogens.

By use of contaminated implements:

Pathogens are transferred from one area to another through implements used in various cultural operations (weeding, thinning, hoeing etc.) in the field.

By use of diseased grafting and budding material:

Grafting and budding between healthy and diseased plants is the most effective method of distribution of pathogens of horticultural crops.