What is causing black marks on Teddy Bear Magnolias?

[Sprayman44]

  

Teddy Bear Magnolia - Black marks on Leaves

Seeking advice on what might be causing the black spots appearing on our teddy bear magnolias trees. There are similar leaves on 2/3 of the trees. It’s appearing on new and older leaves.

They were planted about 4 weeks ago. We have been watering lightly once per day on the advice of the Bunnings nursery. We are based in SA and have had some heat recently, as they are in full sun thinking it might be a heat scorch?

[MitchellMc]

Welcome to the Bunnings Workshop community @Sprayman44. It's fantastic to have you join us, and many thanks for your question about Magnolia care.

Quite likely a heat scorch and possibly lack of water. If you are experiencing some heat in SA, then I'd be going for at least three deep and long waterings per week, and then on those really hot days, a light watering if the soil is a bit toasty. That metal fence directly behind the plants wouldn't be helping either. You can quickly place your hand on it at midday to get a feel of how much heat would be radiating onto the back of the plants; they'd be cooking.

You soil looks very dry from the image. I'd suggest monitoring it and when the top 10cm of depth is almost dry water again.

Let me mention a couple of our gardening experts, @Noelle and @mich1972 to get their thoughts.

Please let me know if you have any questions.

Mitchell
 

[mich1972]

Good morning @Sprayman44 Looks like sunburn to me and also heat reflecting off the Colorbond fence doesn’t help. Best thing to do is put up a temporary shade cloth over it in these hot months and then remove it in April when it cools down. 🪴😃

[Noelle]

I absolutely agree with all that @MitchellMc and @mich1972 have advised. While some of the newer magnolias like Teddy Bear are a little tougher than older varieties, evergreen magnolias generally like warmth, but not heat, and some humidity, not scorching dry air. They also do well in cooler "hills' climates.  Your position looks terribly exposed, which might also account for the rather pale foliage.