Question From:
Sophie in Maroubra, Sydney NSW
Nature of problem:
My potted sapling has developed dark brown, discoloured spots or lesions on the leaves, moreso on the older or lower leaves. Seems to be spreading slowly, but steadily. Leaves drop soon after they turn entirely brown. I bought the plant at the end of autumn as a sapling, pretty much the same size that it is now. Growth also appears to be very slow, but I had assumed that to just be the plant’s nature or a winter thing.
Type of Plant (if known):
Backhousia citriodora (Lemon myrtle)
Symptoms of Plant Illness (please try NOT to diagnose your problems yourself):
Spotting and discolouration on leaves; occasional leaf drop; extremely slow growth.
Soil Type (e.g. sandy, clay or loam) OR Potting Mix Type:
The majority of it is Osmocote’s “Native Potting & Planting Mix”. I don’t know what type of soil was in the nursery’s original pot (which was about 18 x 30 cm), and I also think there are smaller amounts of Osmocote’s “Cacti & Succulents Mix” and Hortico’s “Garden Soil” — maybe a two or three cups of each at most. There is a layer of ANL’s “Eucy” mulch about 3 or 4 cm, as well as some hand-sized rocks and about a cup full of tiny pebbles sitting on the soil surface. TMI?
How often do you water the plant:
Occasionally, but not on a schedule. I use one of those cheap moisture gauges, which I stick through about halfway into the pot. The last time I watered it must have been almost a week ago, and currently the gauge reading is in the “WET” section, which is surprising. I usually allow it to fall back into the “DRY” section, then soak it thoroughly.
How many hours of sunlight does the plant get each day:
Probably somewhere around 4 or 5 hours at the moment, from about 10am to between 2 or 3pm. It hits directly for most of that time.
What type of plant is it:
Please see photos.
How long since you planted it:
I don’t remember precisely, but I think it was the end of autumn, probably some time in either April or May. It hasn’t grown much at all since then.
Have you fertilised? If so, with what and when:
I don’t remember whether I fertilised when I re-potted it, but I somewhat doubt it and I definitely haven’t since. If I did fertilise when I re-potted, it would have probably been with a solution of Organix’s “Harvest Fertiliser Concentrate”.
Is the plant indoors or outdoors:
It is outdoors, against a wall and slightly sheltered. When it rains, the outer quarter of the pot’s surface can get wet.
What other treatments have you given the plant:
None.
Upload photo if available:
photo 4.JPG
Other Comments:
The pot measures 42 cm in diameter by 36 cm height.
Answer: Hi Sophie, Thanks for the excellent information. Lemon myrtles are very hardy plants and I have no idea what is wrong with yours. Does the pot have a drainage hole? It could be half full of water. It could also be caused by salt spray if you are very near the beach. In any case, repot it into a slightly smaller pot, removing all of the new potting mix and cross your fingers. Good luck, Don.
