Late Blight is one of the two fungal potato blight diseases that caused the Irish potato famine in the 1840s. The other, Early Blight, is much less severe. The disease will almost exclusively attack potatoes and tomatoes, rendering whole crops inedible. It spreads incredibly fast in humid and wet weather which is why there are weather warnings sent out to potato growers when there is going to be a stretch of warm, humid weather so that they can preemptively spray a fungicide to protect their crops. This disease is incredibly hard to get rid of once it has established itself as it can survive in rotting potatoes that are not removed from the soil.