Citrus treatment for scale bugs and whether fruit is edible

Question

I have some citrus trees with scale bugs, they are kept as house plants and live outside during the warmer months. They've been sprayed (regrettably) with a pretty nasty pesticide. It's called Bug Clear Ultra and Acetamiprid is listed as being the chemical. (I don't want to use that spray again, but used it under duress).

My question is whether the fruits are edible given they've been sprayed with nasty chemicals (Acetamiprid). Having read the container again (see picture), it gives a guide to 'latest application before harvest', which is some help. Though further reading info provided by the University of Hertfordshire reveals that this is a neonicotinoid and that it can cause skin irritation (scroll to the bottom of the link for a summary of this). I'm still rather unsure whether I can use the fruit or whether it could possibly be harmful.

I'll try out the organic methods next time (mentioned in the RHS link I've provided), does anyone have successful experience of using organic treatments?

EDIT - to add detail following Bamboo's points

• While fruitlets were present? Yes.

• While the flowers were there? Yes.

• Second, can you add a photo showing the extent of the scale infestation, or say whether it is on the leaves as well as on the wood. I don't have a photo of this yet, but there are still scale insects on the leaves. I noticed found one or two on new leaves as well, although I believe I sprayed at the right time; I read somewhere that there is a most effective time to spray, according to the beasties' lifecycle. Perhaps the treatment isn't 100% effective in any case.

Answer 1

Ooh, nasty one indeed - the active ingredient acetamiprid is dangerous to bees. That particular insecticide is both contact and systemic - systemic means it enters the sap stream of the plant, and that includes the fruits.

In theory, you can eat the fruits if you sprayed more than 14 days ago; in practice, I wouldn't eat them, but that's because I prefer to eat organic. For future reference, there are insecticide sprays available designed for use on edible plants such as Bug Clear for Fruit and Veg - these are contact insecticides only and will not enter the sap stream, and are far more environmentally friendly. The reference to acetamiprid irritating skin is if you get the spray on yourself, so that won't be a problem now.

Check the woody parts of your citrus tree, just to make sure there aren't adult scales attached - these look different, more like little shields, often brown, and are firmly attached. If there are any, a cotton bud dipped in methylated spirits and applied to the scale insect should enable you to get it off.