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- Leaf spot disease appearing on Indian hawthorn
(06/03/19) BATON ROUGE, La. — Entomosporium leaf spot is a foliar fungal disease that affects several important woody ornamentals, including Indian hawthorn and red tip photinia.
In Louisiana, it also occurs on fruiting pear, said LSU AgCenter plant doctor Raj Singh.
“Early symptoms on Indian hawthorn appear as small, reddish-purple spots on young growth,” Singh said.
As the disease progresses, the center of the spots turn light to dark gray. Older spots become darker in color with sunken centers and develop yellow halo around them. Leaves turn reddish-yellow before falling off.
“The pathogen survives on the infected leaves on the plant or on leaves fallen on the ground beneath the plants,” he said. “Rainfall and water splashed from sprinkler or overhead irrigation aid in dispersal of spores from older infected leaves to young, expanding healthy foliage.”
Extended periods of leaf wetness are required for infection to occur, Singh said.
Entomopsorium leaf spots can been seen all year round, but the disease develops rapidly under cool, wet weather during fall and spring.
Successful management of Entomosproium leaf spot requires an integrated disease management approach, Singh said.
Removing severely infected plants and plant debris, including infected leaves from the ground, is most important in reducing the disease.
Good cultural practices — including planting disease-free healthy plants in sites with good air circulation, planting in well-drained fertile soils at proper plant spacing, watering early in the morning to reduce the leaf wetness period and following a good fertilization program — help plants grow vigorously and create environmental conditions less conducive for disease development.
“Timely application of fungicides and uniform coverage of plants with fungicides play an important role in managing this disease,” Singh said. “Fungicides containing chlorothalonil, myclobutanil, propiconazole or tebuconazole as the active ingredient may be used as soon as new growth appears in spring.”
Multiple fungicide applications may be required during favorable weather conditions for effective management.
For additional information on fungicide use, check the LSU AgCenter Plant Disease Management Guide at www.lsuagcenter.com.
Initial symptoms of Entomosporium leaf spot on Indian hawthorn. Photo by Raj Singh/LSU AgCenter
Older darker spots on Indian hawthorn. Photo by Raj Singh/LSU AgCenter
Leaf spots on a fruiting pear leaf. Photo by Raj Singh/LSU AgCenter
Diseased reddish-yellow leaves of Indian hawthorn before defoliation. Photo by Raj Singh/LSU AgCenter