View of the whole plant
Close up of leaf.Apparently younger plants are more susceptible, and severe cases result in curling, drying, and browning of the leaves (which this little guy exhibits). Nearly all ornamental plants can get some form of powdery mildew, but species are mostly host-specific. The mildew shows up mid to late summer, and the biggest problem with it is that it diminishes the aesthetic quality of the host plant.
The fungus itself will overwinter on fallen leaves, so I'm assuming that next year's infection could be reduced by removing the leaf litter from around the plant. Ascospores are released in the spring, and carried back to the new leaves via wind or splashed water. In sites with good airflow and well-drained soils, inoculation is less likely. Exposure to full sun also reduces the spread of the fungus. This is certainly observable in my lilacs, as the older lilac has a few lower (thus more shaded) leaves that have a small amount of fungus on them. Overall though, the older lilac largely lacks powdery mildew. Furthermore, the younger lilac is closer to the silver maple in my backyard, possibly increasing the amount of shade that it receives (the maple is south of the lilacs). Interestingly, though powdery mildew is supposed to hasten the fall senescence of the leaves, the older lilac's leaves are showing much more yellow/light green coloration than the younger, highly infected one, which is still largely dark green/crispy brown at some leaf edges.
References:
Nameth, S. and Chatfield, J. The Ohio State University Extension Fact Sheet. Plant Pathology. Columbus, OH.
Partridge, J.E. 2008. Powdery Mildew of Lilac. University of Nebraska, Lincoln Department of Plant Pathology.
The fungus itself will overwinter on fallen leaves, so I'm assuming that next year's infection could be reduced by removing the leaf litter from around the plant. Ascospores are released in the spring, and carried back to the new leaves via wind or splashed water. In sites with good airflow and well-drained soils, inoculation is less likely. Exposure to full sun also reduces the spread of the fungus. This is certainly observable in my lilacs, as the older lilac has a few lower (thus more shaded) leaves that have a small amount of fungus on them. Overall though, the older lilac largely lacks powdery mildew. Furthermore, the younger lilac is closer to the silver maple in my backyard, possibly increasing the amount of shade that it receives (the maple is south of the lilacs). Interestingly, though powdery mildew is supposed to hasten the fall senescence of the leaves, the older lilac's leaves are showing much more yellow/light green coloration than the younger, highly infected one, which is still largely dark green/crispy brown at some leaf edges.
References:
Nameth, S. and Chatfield, J. The Ohio State University Extension Fact Sheet. Plant Pathology. Columbus, OH.
Partridge, J.E. 2008. Powdery Mildew of Lilac. University of Nebraska, Lincoln Department of Plant Pathology.
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2 comments:
I can't believe I read that :D I think the title, "Powdery mildew" just got me goin' a little. It sounds almost exotic.
Lol, everything about plants is awesome.
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