Virocontrol involves biocontrol of pathogens via hypovirulence-causing mycoviruses. This chapter discusses the characteristics of mycoviruses and the conditions that need to be met to make a successful virocontrol agent. The chapter describes one of the success stories so far, that of virocontrol of Cryphonectria parasitica, the chestnut blight pathogen. The chapter ends by reviewing future treā¦