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Chrysanthemum Leaf Troubles #796410

Asked June 17, 2022, 7:17 AM EDT

I have been seeing damage on MANY of my chrysanthemum plants. The damaged plants are all from cuttings that I started this year in my home. They were in a dome with a heat mat and I sprayed them every day so they wouldn't dry out. Now that they are out of the dome and potted, the damage is continuing. I assuming it's some sort of fungus of some kind? I have two questions.... Do I have to throw out all of these infected plants to prevent spread to other plants? If not, what kind of spray/fungicide/treatment can I use to help them get better? Thank you!

Shiawassee County Michigan

Expert Response

Hello,

Chrysanthemums are subject to several leaf spot fungi including Septoria chrysanthemi, S. chrysanthemella, Alternaria species, and Cercospora chrysanthem.   Symptoms first appear as yellow spots which turn brown to black. Spots often occur on lower leaves first and can coalesce into large necrotic areas and finally death of the entire leaf. Small black fruiting bodies may be seen in the lesions of some leaf spot fungi. Leaf spot diseases are encouraged by prolonged periods of leaf wetness and high relative humidity.

Good sanitation is needed. Regularly clean up and destroy infected plant debris and hand pick symptomatic leaves from lightly infested plants. If using overhead irrigation, watering in early morning helps foliage to dry quicker. Fungicides can be helpful. Follow all directions as listed. Clean all garden tools daily.

https://www.canr.msu.edu/resources/bacterial-leaf-spot

https://www.e-gro.org/pdf/362.pdf

https://www.canr.msu.edu/news/scout_garden_mums_for_insect_pests_to_avoid_surprises


An Ask Extension Expert Replied June 18, 2022, 2:37 PM EDT

Thank you for your reply! I will look into all the info/suggestions you have given!

The Question Asker Replied June 19, 2022, 12:10 PM EDT

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