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in Fruit & veg
I have a potted lemon tree which I was thinking I ought to bring indoors again soon, but discovered that a lot of the leaves have light brown spots on them, which you can scrape off with a thumbnail. I guess it's some kind of insect/pest, how do I get rid of it because I really don't fancy it indoors with these on it?
It may be related as it's been stood on the patio next to a large bay tree which I've noticed over the past month or so seems to have attracted loads of wasp type insects - I don't think they're the type that sting you though. There are also some of these brown patches on the bay leaves but also, all around the bay there is a sort of black soot-like deposit on the patio. I tried to scrub this off with soap & water & a stiff brush at the weekend, but couldn't shift it at all.
Does anyone have any ideas what either or both of these problems might be please?
Sounds like scale insects - remove them with your thumb nail or dab them thoroughly with a cotton bud soaked in meths.
The bay tree has probably had some aphids on it - they excrete honeydew which is what the insects (possbly hoverfles, possibly wasps) have been after. The honeydew gets mildewed and turns black. It should be easy enough to remove from the patio with soap and water and elbow grease, or a proprietory patio cleaner.
As for the bay, I would remove the scale insects give the tree a good hosing (not a jet wash but a good strength squirting) to help wash off what remains of the aphids and honeydew - the winter rains will do the rest.
In the spring repot your bay into some good quality compost and feed it regularly - it's weak plants that get damaged by insect pests.
Years ago I grew Orange and Lemon trees in a 18x10 foot heated GH with a variety of Tropical plants. Every year when ready to be brought inside for winter, the leaves of the Citrus were covered in brown powdery areas and sometimes small caterpillars were seen. I sprayed the plants with White and Green Fly killer and removed those leaves with the `beasties` on them. Within a few weeks all the problems had gone and the plants recovered quickly.