When invading a plant what is the first obstacle that plant pathogens must overcome?

The first obstacle that pathogen must first overcome is the physical barriers on the exterior of a plant such as substances that contained protoplast of the plant cells, waxy cuticle or the outer epidermal layer such as bark or thorn. Some pathogens uses the wounds of the plant that was made by an animal or through the stomates and lenticels of a plant to penetrate and damage the plant.

answer; /// i believe the correct answer is (reactants);

equal distribution i think.