AusBonsai

Hey all,

My daughter has her first little juniper that she has been working on. However I have noticed that some of the needles have become discolored and there are little white spots appearing.
We are in ipswich in Qld, which has been a little wet, but very humid and I often wet the needles when watering.
I wonder if anyone can see if this is a problem or not? I have sprayed pyrethrum and confidor over it but was wondering if that was the solution.
I think I have another juniper showing the same symptoms, but my other plants all seem fine.
Thanks,
Steve

Hard to see clearly in the photos but I'd guess some sort of scale insect. They can damage plants when numbers are high so treatment is recommended.
Oil sprays are usually recommended for scale. Eco oil or similar should be effective and is generally less damaging than the older white oils.
Neem oil is a newer treatment that is recommended for scale.
You'll need to use both the above several times over a few weeks to get any new hatchings and any you missed in the first treatment to get full control. Always make sure you spray fully - top and bottom of all leaves and all sides of the plant if possible as both are contact insecticides meaning you must get it onto every scale to kill them.
Systemic insecticides circulate all through the plant after application so any bug that bites the plant will die. More certain eradication as you don't need to touch every pest to kill them. Systemics are getting harder to obtain as there are some possible unintended side effects on non target insects. Confidor is a systemic and should kill the scale.
Pyrethrum is a contact insecticide but cannot get to the insects hiding under the shelters they make so rarely has any effect on scale.

I read that oil based solutions aren't great for junipers as they can stop respiration. I have neem oil and was going to use that, but didn't in case it damaged the plant. Hence the Confidor

I've also seen those recommendations against oils on juniper but have not seen it. I will undertake to do some tests soon to find out first hand.

The confidor should clear up any scale but keep a close watch next spring to make sure a few have not survived or moved in from elsewhere.

I had really good results using a 70% isopropyl alcohol wipe. The scales just flaked right off and I kept coming back to it each day to examine - if they came back I wiped again.

Took about a week or so before they were completely gone, but they were heavily reduced (90%) after the first wipe.

Forgot about alcohol. It is also a contact insecticide so needs to get on or very near the insects. Sometimes it is hard to make sure you reached all the small spaces where they are hiding but repeat applications usually gets most of them.
I've sprayed with metho a couple of times and that works too.

I wonder if diluted hand sanitizer might also do the trick. There’s heaps of it around these days.
I’ll see how the confidor goes as well. I didn’t realise that the scale can hang around for seasons.

Stevie_B wrote: ↑April 28th, 2023, 11:55 am I wonder if diluted hand sanitizer might also do the trick. There’s heaps of it around these days.
I’ll see how the confidor goes as well. I didn’t realise that the scale can hang around for seasons.

I wouldn't use diluted hand sanitiser. Most hand sanitisers are at or below 70% alcohol, so diluting it would dilute the strength. + they could contain other things which aren't good for the foliage.

Shibui mentioned metho (methylated spirits) works too. I think the main thing I like about iso/metho is that it will evaporate quickly so it doesn't remain on the tree longer than it needs to.

Call me old fashioned, but I would ONLY use products that are approved for controlling the particular pest/disease. The Australian Pests and Veterinary Medicines Authority (APVMA) is a body jointly owned by the States, Territories and Commonwealth and it registers products nationally. The labels of all the products designed to manage pests must be approved by the APVMA so they only make claims supported by the science and they define the purpose for which the product is approved. And by 'approved' I mean shown to be effective in controlling the pest AND safe to use on your plant.

In the case of scale, the pest oils already mentioned are the way to go - or any other product you find that is approved for managing scale.

Phil Rabl wrote:Call me old fashioned, but I would ONLY use products that are approved for controlling the particular pest/disease. The Australian Pests and Veterinary Medicines Authority (APVMA) is a body jointly owned by the States, Territories and Commonwealth and it registers products nationally. The labels of all the products designed to manage pests must be approved by the APVMA so they only make claims supported by the science and they define the purpose for which the product is approved. And by 'approved' I mean shown to be effective in controlling the pest AND safe to use on your plant.

In the case of scale, the pest oils already mentioned are the way to go - or any other product you find that is approved for managing scale.

I agree. Why go for some alternative or home grown remedy when there are any number of dedicated products available.


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Yep. That is a good point, actually.
I was just looking for something else to do with my hand sanitizer, as no matter how much cordial I mix it with it still tastes rubbish.

Stevie_B wrote: ↑April 30th, 2023, 2:27 pm I was just looking for something else to do with my hand sanitizer, as no matter how much cordial I mix it with it still tastes rubbish.

There’s a reason Australian emergency departments have to keep their hand sanitiser away from the bedside…