Scab is a fungal disease caused by fungi belonging to two different genera: Diplocarpon or Marssonina, which attack ornamental plants, and Venturia, which affects fruit trees.
The ornamental plant most commonly affected by this disease is the rose. In the vegetable garden, however, apple trees, pear trees, and medlar trees are the main victims.
The ideal climatic conditions for the development and spread of the disease are high humidity caused by rain and night dew combined with warm temperatures, around 20–25°C.
For this reason, it is limited to late spring and early autumn in northern regions, while in central and southern areas it can spread for much longer.
