Blight

Blight is a fungal disease that is propagated by wind-borne spores. As a result, spores can quickly transmit the virus across broad areas.

Blight can only spread in warm, humid conditions, especially when temperatures are over 50°F for two days in a row and humidity is above 90% for eleven hours or more. There is no cure. The only option is to avoid it in the first place.

Blight can be controlled by disposing of plants contaminated with the disease, keeping blight-infected plants out of the compost, pruning and staking plants, disinfecting pruning shears with one part bleach and four parts water, and adding organic compost to the soil beneath the plant.