Are biopesticides protective or curative?

Biopesticides are more effective when used in a prophylactic preventative programme, not dependent on thresholds or scouting. The colonization of the rhizosphere by beneficial microbes in advance of the attack by pathogens and pests will reduce the living space on the roots where the pathogens might attempt to colonise. Beneficial microbes will secrete substances, which can slow down the growth of the competing pathogenic microbes or kill them. This will reduce the level of disease or pest attack on the plant.