Entomosporium Leaf Spot Photinia and Indian Hawthorn

Kevin Ong, Assistant Professor and Extension Plant Pathologist

Symptoms

The first signs of Entomosporium leaf spotdisease are tiny, circular, often bright redspots on both surfaces of young expandingleaves. Small spots may coalesce to form largepurple to maroon blotches on heavily diseasedleaves. On Indian Hawthorn, blotches are typ-ically bright red. Leaf spots on mature leavesof most plants have ash brown to light graycenters with a distinctive deep red to maroonborder. On pears, the border of the leaf spot istypically brown and thin. Tiny black specks,fruiting bodies of the Entomosporium leaf spotfungus, are often found in the centers of thespots. Spots can also occur on leaf petiolesand tender shoots.

Entomosporium (en tow moe spo ree um) leaf spot often damages red tip photinias (Photinia fraseri) and Indian

Hawthorn (Rhaphiolepis indica) plants. Thisdisease is a widespread and destructive fun-gal disease of woody ornamentals in the rose(Rosaceae) family. Other hosts for thispathogen include loquat, flowering and fruit-ing pears, firethorn and quince. The disease ismost damaging to plants in home landscapesfollowing periods of frequent rainfall in thespring and fall when temperatures arebetween 60 and 80 degrees F and when theplant is actively growing.

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Conidia (spores) of the Entomosporium leaf spotfungus. Entomosporium leaf spot on Indian Hawthorn.

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Texas AgriLife Extension Service

Although light infections by this fungus usu-ally produce minor “cosmetic” damage, severeinfections can cause premature leaf loss.Severe leaf drop greatly reduces the land-scape screening value of the plants, slowsgrowth and increases the plant’s sensitivity toenvironmental and cultural stresses.

Disease Cycle

Spots on leaves, young shoots and fallen dis-eased leaves are important in the survival ofthe Entomosporium leaf spot fungus. Massesof spores are released from late winterthrough much of the growing season. The fun-gal spores are spread to healthy foliage by acombination of splashing water and wind.

Under favorable conditions, spores germinateand infect young growth. Symptoms typicallyappear 10-14 days after infection.

Control Tips

✔ Purchase only healthy plants that do notshow leaf spot symptoms.

✔ Space plants adequately to allow good airmovement. This helps to promote rapiddrying of leaves and reduces the chancesof infection.

✔ Remove fallen diseased leaves, particu-larly in the winter prior to the plant’snew growth in the spring. This reduces asource of fungal spores available for newinfections.

✔ Water only when necessary. This pre-vents excessive new tender growth. Whenit is necessary to water plants, do it earlyin the morning to allow the leaves to dryfaster with the morning sun. This mini-mizes the time that the foliage stays wet.Surface or drip irrigation is the preferredmethod of watering since the leavesremain dry. Alternatively, adjust sprin-klers to reduce or prevent splashing andwetting the foliage.

✔ Prune plants selectively and infrequentlyto help prevent excessive new growth.

Severe leaf spots on Photinia.

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Entomosporium leaf spot.

Avoid fertilizing the plant during thesummer to limit excessive plant growth.New, succulent growth increases the sus-ceptibility of the plant to infections.

Fungicides, such as thiophanate-methyland myclobutanil, can be used effectivelyto prevent Entomosporium leaf spotswhen conditions become favorable for

developing the disease, such as in cool,wet weather with diseased plants grow-ing nearby. Consult your local Extensionagent or retail nursery for the properfungicide to use when such situationsarise. Always refer to product labels forinstructions on proper usage of the fungi-cides. Fungicide applications are not nec-essary during hot, dry periods.

Entomosporium leaf spot.

Adapted from previous version of publication by Janell Stevens Johnk.