Leaf spot diseases can be hard to control when they occur on susceptible plants. Plants such as Dwarf Hawthorne, roses, Photinia (redtip), hydrangea and laurel are extremely susceptible especially when conditions are conducive to the development of disease.
For instance overhead irrigation can allow leafspot fungi to develop rapidly causing severe cosmetic damage to the plant often leading to defoliation.
Treatment for these leafspot fungi is available but are of only limited help if the plant is susceptible or grown in poor conditions. The best bet is to not plant susceptible varieties or if you do choose to make use of these varieties, plant them in optimal growing conditions.
