Leaf spot, caused by the fungus Entomosporium maculatum, is a widespread and destructive disease. This disease is most damaging to plants in the landscape and nurseries during periods of cool, wet weather and when active growth is occurring. Low levels of leaf spot are usually purely aesthetic. Severe infections can result in early and heavy leaf drop. Heavy leaf drop severely reduces the landscape value of red tip photinia and can cause plant death.
Treatment Strategy
Provide adequate fertilizer and water. Avoid overhead irrigation, and/or water early in the day. Avoid excessive pruning of hedges. Rake and dispose of fallen leaves offsite.
Other Treatment Practices
- Watering
- Irrigate once a week during extended drought periods.
- Do not use overhead irrigation: use drip or trickle irrigation instead to keep the foliage from getting wet.
- Mulching
- Mulch is very beneficial for all trees because it reduces competition with turf and moderates soil temperature and moisture levels
- Maintain a 2-3 inch deep layer of composted mulch over the root zone.
- Sanitation Rake and dispose of fallen leaves offsite.
- Treatment with Trimtect has proven to help plants be more resistant to this disease.
Limb/Foliar Spray Using Myclotect
Limb/Foliar Spray Using Talaris 4.5F
Expected Results
Entomosporium will always be present in the landscape, and treatment must focus on suppression, not eradication.
Signs of Damage
- Tiny, circular, bright red spots on both the upper and lower surfaces of young expanding leaves are the first symptoms
- Numerous small spots may coalesce into large maroon blotches on heavily diseased leaves
- Leaf spots on mature leaves have ash brown to light gray centers with a distinctive deep red to maroon border
- Tiny black specks, spore producing bodies of the fungus, can often be observed in the center of each leaf spot
- Spots similar to those on the leaves can develop on leaf petioles and tender stem growth during prolonged periods of cool, wet weather
Photo: Gerald Holmes, California Polytechnic State University at San Luis Obispo, Bugwood.org
Photo: Entomosporium leaf spot on red tip Photo: North Carolina State University
Trees At Risk
- Red tip photinia (Photinia fraseri)
- Loquat (Eriobotrya japonica)
- India hawthorn (Rhaphiolepis indica)
- Some pear cultivars (Pyrus sp.)
Biology
- Masses of spores are released during periods of wet weather from the fungal spore producing structures in the center of the spots from late winter through much of the year except during the hot periods of summer. These spores are spread to healthy foliage by a combination of splashing water and wind.
- New leaf spot symptoms appear within 10-14 days after a wet infection period.
References
Alabama A & M / Auburn University Extension
https://www.aces.edu/blog/topics/landscaping/controlling-entomosporium-leaf-spot-on-woody-ornamental/
Texas A & M Agrilife Estension
https://agrilifeextension.tamu.edu/library/landscaping/entomosporium-leafspot-of-photinia-and-indian-hawthorn/
Always refer to product label for rates and approved uses. Some images courtesy of forestryimages.org or Wikimedia Commons. Use of the images does not imply endorsement of treatments.
