Cristulariella leaf spot – Bullseye Pattern on Crapemyrtle Leaves
Q: My crape myrtles have developed a brown bullseye pattern on some of the leaves. The ones with the spots will simply fall off at the lightest touch. The backside (underside) of the affected leaves have a tiny white spikes that can barely be seen with the naked eye. This seems to have developed in just a few days.
A: I had never seen this before so I sent these photos to a group of smart friends. The group included landscapers, gardening experts and tree care professionals. There was a lot of guessing (I said it was a virus.) But Lyle Collins at southerntrillium.com was the astute researcher who came up with an answer.
The disease is Cristulariella leaf spot. I would be willing to bet real money that 99.9% of Atlanta landscapers have never seen it or heard of it. Do you have any theories about how your crapemyrtles got it?
You described it perfectly: bullseye pattern, leaf falls prematurely, and tiny white spikes on backside of leaf.
The only control information I could find recommended an application of a systemic fungicide that contains thiophanate methyl (CLEARY 3336, DOMAIN FL, SYSTEC 1998, FUNGO, FUNGO FLO etc) which may prevent infection of susceptible plant tissue or slow disease development of infected plants.
Raking and destruction of infected leaf litter is an excellent way to lower the fungal inoculum, and will reduce the potential for future disease outbreaks.
More details here: Cristulariella Leaf Spot