Phlox brown - Ask Extension
Potted phlox bottom leaves turning brown past few weeks. Nothing on leaves like spots or whitish or anything. Not turning yellow to brown, just goes s...
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Phlox brown #842917
Asked July 27, 2023, 3:46 PM EDT
Potted phlox bottom leaves turning brown past few weeks. Nothing on leaves like spots or whitish or anything. Not turning yellow to brown, just goes straight brown. Thank you
Macomb County Michigan
Expert Response
Hi Chris,
The edges for the leaves are brown and dry. The areas between the margins have yellow spots. These are symptoms of leaf scorch.
Leaf scorch can be caused by environmental conditions as well as bacteria. Scorch typically occurs during the hot summer months. Leaf scorch is usually due to one of the following:
Heat and sun exposure: If plants are exposed to intense sun and high temperatures, they become stressed. Garden Phlox is a full sun to part sun plant, however they prefer some shade in hot afternoons. Check the location of your plant, does it receive intense afternoon sunlight? If it does, consider moving the plant. Increase watering during times of high temperatures.
Poor root growth: Not likely in your case as this is due to compacted soil, poor drainage and lack of fertilizer.
Bacteria: Leaf scorch can also be caused by the bacteria Xylella fastidiosa. This is a chronic disease that reoccurs every year, even with treatment. Bacterial leaf scorch affects older leaves first and does not impact younger leaves, which distinguishes it from environmentally-cause leaf scorch. Bacterial leaf scorch cannot be cured, so it is best to remove the infected plant to prevent spread to other plants.
Thank you for using Ask Extension.
Pam V.
MSUE Advanced Master Gardener
The edges for the leaves are brown and dry. The areas between the margins have yellow spots. These are symptoms of leaf scorch.
Leaf scorch can be caused by environmental conditions as well as bacteria. Scorch typically occurs during the hot summer months. Leaf scorch is usually due to one of the following:
Heat and sun exposure: If plants are exposed to intense sun and high temperatures, they become stressed. Garden Phlox is a full sun to part sun plant, however they prefer some shade in hot afternoons. Check the location of your plant, does it receive intense afternoon sunlight? If it does, consider moving the plant. Increase watering during times of high temperatures.
Poor root growth: Not likely in your case as this is due to compacted soil, poor drainage and lack of fertilizer.
Bacteria: Leaf scorch can also be caused by the bacteria Xylella fastidiosa. This is a chronic disease that reoccurs every year, even with treatment. Bacterial leaf scorch affects older leaves first and does not impact younger leaves, which distinguishes it from environmentally-cause leaf scorch. Bacterial leaf scorch cannot be cured, so it is best to remove the infected plant to prevent spread to other plants.
Thank you for using Ask Extension.
Pam V.
MSUE Advanced Master Gardener
