Blight
Blight is a disease that infects domesticated plants with a growing period shorter than 15 days.
Blighted crops will not grow or yield anything when harvested, and can spread the blight to other nearby plants while losing health points and dying.
Progression
Blight starts on one species of plant, at 10% severity, affecting 20% of your plants (40% initial plants affected has been witnessed in December of 2020). It will progress slowly once plants are infected, and once it reaches 28% it can spread to nearby plants within a 4-tile radius.
Unaffected Plants
Trees, wild, and decorative plants are immune to blight, as well as domesticated plants with a 15-day or longer growing period (e.g. devilstrand mushroom, cocoa tree, etc.).
Removal
To stop blight, the affected plants need to be manually selected for cutting (using the right-click plant cut command, or in the Orders tab of the Architect menu), or burned with Molotov cocktails or Incendiary launchers, though burning the plants may be inaccurate and kill plants that are not blighted.
The advised method to deal with a blight outbreak is to set up a plant cutting order for all blighted plants and quickly set plant cutting to priority 1 for everybody. Once the blight has been dealt with, reset the priorities.
Mitigation strategy
To mitigate the effects of blight, it is recommended to leave 3-square wide strips between crops, left empty or planted with species not affected by blight.