Can leaf spot spread?

Asked June 1, 2017, 12:44 AM EDT

My Neighbor has leaf spot in their photinia. On my side of the fence, have rhododendrons and roses. Can my bushes get leaf spot from the dropping leaves?

Josephine County Oregon plant disease horticulture

1 Response

The conditions that cause the fungus commonly known as black spot affect your neighbor's photinia as well as your own roses and rhodendrons. Our warm, wet spring is the ideal condition for leaf spot to develop. While different fungi may infect your neighbor's photinia, your rhodies and roses, the cultural controls are the same:

  • --Space or prune bushes to allow for good airflow. Avoid dense plantings and shaded areas.
  • --Avoid overhead watering that keeps plants wet for extended periods of time. Try using a soaker hose that does not spray water on the leaves. Or if you overhead water (sprinklers) do so in the morning so the leaves will dry quickly.
  • --Rake up and destroy all fallen leaves. Do not put them in your compost pile.
  • --Remove and destroy infected plant parts.
  • You will have to persuade your neighbor to clean up his fallen leaves and to avoid overhead watering in late afternoon.
  • You may want to try a fungicide if the black spot is widespread. Follow all label directions.
  • Ultimately, the hot, dry summer to come will overcome the disease. But clean up well in the fall so the infected leaves are not left around to re-infect come spring.
  • For more information on rose leaf spot, click on the following link: https://pnwhandbooks.org/plantdisease/host-disease/rose-rosa-spp-hybrids-leaf-spots-miscellaneous.
  • Thanks for using Ask an Expert.