Scale insect infestation on my lemon tree!

[veggiewomble]

Good day, all.

I have a 3 year old lemon tree growing on a terrace balcony, in a large(ish) pot. It's only about 3 ft tall and hasn't done very well through the years, possibly because it doesn't get as much sunshine as it would like. However I have neglected it in the past months, only to discover in the early spring that most of the leaves have fallen off, and an odd woolly substance on some of the stems.

Upon closer inspection, I found at least a dozen scale insects clinging onto the stems and branches. I squashed them whenever I found them, but feared for the health of the lemon tree. Now, a few weeks later, the tree has lost ALL its leaves and I have just destroyed the last vestiges of the scale insects. I have many other plants on the balcony (roses, hydrangeas) and none of them have been touched - all the insects seem to have targeted this tree.

I'm not sure if the lemon tree is dead? The stems are still green. What should I do to prevent re-infestation again? Not sure where the insects came from as I am in the middle of the city.

[Jeanied]

Check that you haven't got vine weevil by checking the roots are OK. Give it a good citrus feed - I buy the little pipettes that you snip the tops off and place upside down in the compost. It may well come back. If there are any more scale insects lurking around a cotton bud dipped in meths is supposed to deal with them.

[starloc]

If you can find a pesticide with imidacloprid in it , mix up some and water the plant with it ( only when plant needs watering next ) , a soil drench kills insects that feed on the tree

Theres a few things you can spray with, again imidacloprid can be used , but dont put plant outside for about 6 weeks as it can effect bees ,
you can also use a mix of 1 teaspoon neem oil and a tiny drop of washing up liquid in a litre of water
or a teaspoon of a chemical called limonene ( available on ebay ) , its pure distilled orange oil , put it in a litre of water with a tiny bit of washing up liquid

Spray the tree , make sure you soak it everywhere ( try to keep soil dry ) , then rub the branches with a cloth and spray again

If you can see the scale insects its usualy just a blob that contains them , there will be thousands of tiny ones you cant see

The problem with pesticides ( not neem or limonene ) is that if sprayed ( not a soil drench ) shortly after treatment for some reason they tend to cause an infestation of spidermites , so the oils are better as they kill more quicker

[mothhawk]

Do check with chemical spray, that the fruit will be safe to eat afterwards. Several years ago, when my dwarf lemon got scale insects, I tried for 3 years to get rid of them without using chemicals 'cos I couldn't find one that would do the job without making the lemons unfit to eat. In the end I conceded defeat and threw the plant out.

[starloc]

All the trees bought have been treated with a soil drench of something like imidacloprid to stop spread of desises due to insects , if there is fruit on the tree it takes about 6 weeks with imidacloprid for it to be safe before eating after treating.

it depends on the pesticide you use , the neem and limonene are totaly safe natural products and non systemic so dont enter the plant at all, the imidacloprid is systemic but only lasts a very short time in the plant

[shaunbrook]

You said you have had it on your balcony for three years? Have you ever brought it inside when the temprature drops below 10 degree celcius??? I worship my citrus plants and got the dreaded white scaled bug from hell! i picked them all off and it seemed to work quiet well. Tweezers + 2-3 hours = healthy tree=]

Do you mist it every day??? I do mine last thing at night and feed them once every 2 weeks.

Hope that helps???

[veggiewomble]

Thanks for your thoughtful replies.
It hasn't dropped below -10C that often in central London but the one time it did I was abroad, but the trees seemed to have survived it. Unfortunately, having a small flat, there isn't any real space to bring the trees inside to, so I have to rely on fleece and a bit of luck when it gets really cold.

I don't eat the fruit so I just have the trees for ornamental purposes... I do have strawberries growing nearby though, so would prefer not to spray them with any harmful pesticides. Will try the limonene and get back to you all.

I have been treating my soil with nematodes to combat vine weevils, so I do hope it isn't that! I thought I'd controlled the problem for a while now...

vegwomble

[starloc]

Water them with the pesticide and spray with the other,

The pesticide could affect the nematodes....ive no idea! , I use vineweevil killer pesticide if needed, never needed it very often