How to treat Teddy Bear Magnolia spotted leaves?

[lisa15]

Hi,

We planted a row of teddy bear magnolias in February this year in our new home in Adelaide that seem to be growing well but we've noticed these spots/discolouration on the leaves. We water with drip irrigation a couple of times per week, had imported quality soil for the garden and regularly add rooster booster. Do you think this is a fungus? I haven't spotted any bugs on the trees.

 

 

[JacobZ]

Hi @lisa15,

Welcome to the Bunnings Workshop community, it is fantastic to have you with us.

It certainly looks like it could be a fungal issue, although I am not 100% certain. Allow me to tag @Noelle, who is an extremely experienced horticulturalist, for her thoughts.

I suspect removing and disposing of affected leaves and treating with Mancozeb would be the way to go, but I would like to double-check and see what she thinks first.

It is likely related to the spotting on the leaves, but there is also some yellowing and discolouration on some leaves that could imply a nutrient deficiency. Considering you are topping up the soil with Rooster Booster, it is somewhat unlikely that it is an issue with the availability of the nutrients, but with the plant's ability to uptake them. This is common when the PH balance of the soil is not optimal for your plants. Magnolias thrive in slightly acidic soil with a pH range of 5.5 to 6.5. If you grab a Manutec Garden Care Products Soil PH Test Kit and check your soil, if it is outside of this range, you should read through How To Test And Adjust Your Soil Ph for some guidance on rectifying this issue.

I'll also tag our knowledgeable gardeners @robchin and @mich1972 to see if they have any thoughts.

Jacob

[Noelle]

Hi @lisa15 

I think Jacob's hit the nail on the head when he suggested pH testing your soil. In general Adelaide's soils tend to be neutral to slightly alkaline (limestone soil), and the symptoms exhibited on the Teddy bear leaves suggest to me the plants are not happy in the soil they're growing in. There may be some fungal disease present as a consequence.

SO start with the pH test and then adjust your soil according to the link Jacob recommended (How To Test And Adjust Your Soil Ph) and then wait patiently to see if your magnolias' condition improves. It may be a slow process so don't expect results in a matter of weeks - more likely months.