White scale on citrus

Has anyone had trouble with this scale on their citrus trees. We have suddenly discovered it following sooty mould which doesn't rub off easily! I contacted 2 garden centres and opinion varied, sounds difficult to get rid of. Any 'household' treatments advised and should I scrub off the white parts?

Neem oil.

Any oil. winter spraying oil, mixed with copperoxychloride should take care of sooty mould and scale. dont bother with scrubbing scale off, it is an insect and the oil will suffocate it. as will neem oil .

Thanks for help, the sooty mould looks so awful, only hand rubbing seems to remove it, long process!

As said above, spray with any spraying oil and pay particular attention to spraying the underside of the leaves and stems as the scale will seldom be on the waxy leaf tops.
Here is a link to id some of the things you will find on your citrus, spraying oil will blast most of them.
http://cals.arizona.edu/crops/citrus/pcaphotos.html

If you want to clear up the general look of the lemon, spray the oil as advised, then approx 2-3 weeks later give the bush a bloody good hose off at pressure to remove the worst of the mould.
The next day reapply some more oil, then again hose off in 2-3 weeks.
This will clean up the look of it.

Thanks - we will get down to doing these things, once our wet spell is done with.

Doesn't work.

But you don't say what does!
Oil smothers them, as would a good detergent, therefore they fall off.

Here's my advice. I work in a garden centre and also run a plant nursery. I'd say white scale or thrips is not worth the effort to cure if you live in a town or city, however feel free to give it a go anyway.

White scale and thrips will both cause black sooty mould on citrus. They generally go hand in hand. White scale and thrips are insects that drink the sap of the tree. You will find that black sooty mould is a fungus that grows on this sap. It's pointless to try to do anything to remove the sooty mould unless you eliminate the white scale/thrips first, which is the source of the sap. Once the source of the sap is gone the sooty mould will stop growing and die off. Thrips in particular will live on the underside of the leaves to avoid the sun. White scale will usually be on branches and woody growth, although you can find it under leaves too. Again, this is usually out of direct sunlight.

In your case if you eliminate the white scale you should also be removing the cause of the sooty mould. You will probably find your citrus will have thrips too.

In general, there are three ways to cure this. Most are very labour intensive.

The first and most successful way is to give the citrus tree a systemic insecticide. This I wouldn't advise for edible food as recently most systemic insecticides have been removed from sale due to them being suspected carcinogens. You can never guarantee that these chemicals will be entirely eliminated from the plants system or that it won't end up in the edible fruit. FYI Neem granules are a systemic insecticide no matter what people in the garden centres might try to tell you.

The second method is to coat both sides of every leaf and branch that has thrips/scale (you may as well do the entire tree from top to bottom) with a contact insecticide. The best one to use for this is something containing the active chemical Pyrethrum in it. Pyrethrum is good because it is a natural plant extract that breaks down in direct sunlight over 12 hours or indirect sunlight over 7 days. It is not absorbed by the plant and is water soluble so it can be washed off easily (do make sure to wash the fruit before eating if you do this, just in case). It is extremely effective at killing tiny insects and also acts as a short term bug repellent. It's recommended to repeat the treatment every 7 days until you have cured your citrus or the bugs will breed and spread everywhere again.

The third way is what some other posters have mentioned. Use an oil or something like detergent to coat the thrips/scale to suffocate them. Again, just like with the contact insecticide, you will have to cover every part of every plant that has thrips/scale. If you miss any they will breed and come back again. You will also have to repeat this regularly to ensure you eradicate the insects.

In saying all of that, even if you do manage to cure all of your citrus, if you have any neighbours nearby that also have citrus that has white scale or thrips then you can expect it to spread back to yours every summer unless they cure it too. This is the reason why I say it's not worth the effort to cure. If you're successful you'll probably have to it again every year anyway.

Thank you so much for such a full reply, we certainly have material to think about now.

Yep, I agree, If the tree is big enough, it copes. It's an endless process, we did the above garden person advice, it comes back eventually.

Best I have found was a dilute solution of wet and forget but you do need to keep on top of it. I tried everything that was meant to get rid of soft scale and this was the only thing that worked did come back a year later as I wasn't vigilant so back playing catch up now.

High pressure hose also helps blasts the buggas off.

I disposed of all the fruit as wet and forget doesn't have a withholding period due to not being a plant spray.

I think once you have it under control its a matter of keeping the plents in a healthy condition ferts / minerals etc. As our neighbours citrus don't have it. It also affects our sudapanics (spelling?) and another bush so check the other plants and treat as well.