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! Tan spots Zoomed in Photo #362186 - Ask Extension


! Tan spots Zoomed in Photo #362186

Asked September 13, 2016, 9:38 AM EDT

Re previous submission "What is causing tan spots" Here is a close-up photo.

Montgomery County Maryland

Expert Response

It is hard to say for sure what is going on here. How does the whole patch look? Is it blooming? Any problems with the flowers?
Marigolds are generally pretty tough, and anything that does bother them tends to be outgrown.
Possibilities that come to mind include rasping damage from plants bugs or tiny thrips (look for insects, but they could be gone now). We see a squiggly line or two which suggests a leaf miner that feeds between the leaf surface. They are not serious either.
Another possibility is a disease of some sort like botrytis, but that would likely eventually show up as a hairy, grey mold on the flowers too.
This late in the season we wouldn't worry too much and do not recommend control.
You might consider pinching some of the plants to increase airflow. Do the soaker hoses spray up droplets? The leaves in your photos look wet, which would encourage disease.


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