Home grown potted oaks
In autumn this year I collected some acorns from a colder part of the country and attempted to grow them. I am very pleased and excited to have 14 trees currently growing in my city flat! I live in a subtropical area and am not sure how they will fare here.
They have been doing fantastically for nearly 6 months but now I have noticed some white patches on some of their leaves (not all the plants) and today, some of those white patches have gone brown and a couple of leaves fell off! I had thought it might be due to lightly spraying some insect spray near their pots in order to get rid of the pesky fruit flies that live in their sand. But now I'm not so sure.
Can anybody shed any light on what is happening and how I can stop it? The fallen leaf in the one pic has brown spots which might not be clearly visible.
Thanks very much to anyone who can help!