Brown spots on Forsythia leaves - Ask Extension
We have three large forsythia bushes on the front of our property. We have found brown patches on most of the leaves of the far right bush and some o...
Knowledgebase
Brown spots on Forsythia leaves #800055
Asked July 08, 2022, 12:22 PM EDT
We have three large forsythia bushes on the front of our property. We have found brown patches on most of the leaves of the far right bush and some on the middle bush as well. There are a few on the left bush too. The leaves are also turning brown and yellow and see to be "folding in". Can you help us determine what this is and what we can do to repair this? We think it is a fungus that is spreading. Thank you so much for any help you can give us - it's spreading!
Orange County Vermont
Expert Response
Can you tell us what these spots are and can these bushes be saved or do we need to take them out to stop further spreading of whatever fungus this is to other trees/bushes that are in the area? Every leaf on the furthest forsythia to the right has these brown spots. The middle bush has probably 3/4 of the leaves covered with these brown spots and the bush on the left has probably 1/4 of the leaves covered. Thank you for your help. Our local landscaper does not know what the spots are and suggest we contact you.
Hi Donna. It does appear from the photos that your forsythia bushes do have a fungal disease. In consulting with our Plant Pathologist, Ann Hazelrigg, it is probably caused by poor air circulation, hence the leaves do not dry out between rain periods. This fungal problem should not spread to other trees and shrubs in your landscape since most pathogens are host specific.
Here are some recommendations from her that should help with the problem.
- The shrubs look really healthy generally but do require pruning to provide needed air flow between the shrubs and between the branches of each shrub. Although pruning of forsythia is best done right after the bloom period, pruning now may help control the spread between shrubs. This fungal problem will continue if proper pruning is not done.The following bulletin from from the University of Maine Cooperative Extension provides great information on pruning forsythia:
https://extension.umaine.edu/publications/2513e/
- Rake up and destroy all leaves in the fall to get rid of the spores/inoculum that will overwinter in them. Bag them and send them to the landfill.
- Fungicide sprays applied in May and June may help keep the disease at bay but will be persistent if pruning is not done. Copper based fungicides are an organic source that you could find at a nearby garden center.
The three shrubs seem to be providing a nice hedge on your street frontage. Following good pruning practices as outlined in the University of Maine bulletin could still allow for this to remain and improve the health of the shrubs.
Here are some recommendations from her that should help with the problem.
- The shrubs look really healthy generally but do require pruning to provide needed air flow between the shrubs and between the branches of each shrub. Although pruning of forsythia is best done right after the bloom period, pruning now may help control the spread between shrubs. This fungal problem will continue if proper pruning is not done.The following bulletin from from the University of Maine Cooperative Extension provides great information on pruning forsythia:
https://extension.umaine.edu/publications/2513e/
- Rake up and destroy all leaves in the fall to get rid of the spores/inoculum that will overwinter in them. Bag them and send them to the landfill.
- Fungicide sprays applied in May and June may help keep the disease at bay but will be persistent if pruning is not done. Copper based fungicides are an organic source that you could find at a nearby garden center.
The three shrubs seem to be providing a nice hedge on your street frontage. Following good pruning practices as outlined in the University of Maine bulletin could still allow for this to remain and improve the health of the shrubs.
