A: First route I recommend is ensuring a positive diagnosis, whether that be from a county extension agent, master gardener, certified arborist or plant professional at a nursery, or from extensive internet research done visiting only reliable sites. By reliable, I’m referring to sites hosted by nearby universities’ cooperative extension agencies. Make sure the web link you’re following from search engine results ends in ‘.edu’. I get great information from University of Georgia Extension, Clemson’s Home & Garden Information Center, NC State Extension and University of Florida-IFAS Extension.

Often, cercospora leaf spot is manageable on most deciduous trees. It can occur when plants are too crowded with little to no air flow, humidity is high, and with rainy conditions throughout late spring and early summer. Many plants are now bred to have some resistance.

In the case of a crape myrtle or other large tree, application of a systemic fungicide may be applicable, since spraying the leaf canopy isn’t practical. Keep in mind that once the spot shows up on a leaf, that tissue is permanently damaged. So preventing the spread of spores from leaf to leaf is the objective of a fungicide.

Once the leaves fall, the tree is no longer affected, but DO remove affected, fallen leaves from around the base of the tree or plant, as fungal spores can overwinter at the soil level. Replace mulch and always keep it pulled back a few inches from the base of the trunk.

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