Problem With Plumbagos

Question

We planted a number of plumbagos at our Florida vacation home in July. They are in partial shade with sandy soil and are on a drip irrigation system. For some reason parts of the plants are turning completely brown while other parts are green and blooming. This has been going on for a while. Any ideas? This photo was taken last week, mid November.

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Answer 1

If it is overwatered and root rot is setting in, the plant could start declining this way. But you said it has been going on for awhile. Does it sit in water after a rain or after irrigating? If so, it could be a drainage issue.

It also could be overfertilization that is burning the roots. Check how often you fertilize. If you use a slow release fertilizer it should be good for 3 months at least.

Did you check to see if there is any damage at the base of the plant, where the stems might be broken?

Do the leaves have any spots on them before they turn brown? If so, it could be a fungal issue. In that case you can try spraying with Neem oil.

Hope that helps!

Answer 2

According to the article below, plumbago is not usually bothered by pests or disease. However, I would check the brown limbs for any pests like aphids or scale. Also, in the photo, it looks like the brown stems are in the shade. It is possible it is browning because of lack of sun. If there is evidence of a white powder on it, then powdery mildew has attacked the shady areas.

Another possibility to check for are places near the base where something has been chewing, preventing the uptake of water and nutrients to those stems.

Here are some articles that should help:

https://www.gardeningknowhow.com/plant-problems/disease/get-the-cure-for-powdery-mildew.htm

https://www.gardeningknowhow.com/plant-problems/pests/insects/control-plant-scale.htm

https://www.gardeningknowhow.com/plant-problems/pests/insects/controlling-aphids-and-ants.htm

https://www.gardeningknowhow.com/ornamental/shrubs/plumbago/growing-plumbago-plants.htm

Answer 3

Thanks so much for the response. I'll definitely check for any insects. If it were a sun issue wouldn't it effect the entire plant? What about watering? If it's over watered or under watered could that cause this sort of damage or would that effect the whole plant equally? Thanks again!