Mealy bugs and scale

[Randy Linke]

I have unfortunately discovered that a 10m tall Laurus nobilis that is planted on our rear patio is severely infested with mealy bugs and scale.  We recently bought the property and the upper part of the tree was obscured by some tacky metal roofing which hid the obvious damage to the upper branches of the tree and also prevented the sticky honeydew from the insects from hitting our patio.  The tree had been very badly pruned over the years, which was obvious to us.

Is there anything short of cutting the tree down to treat it?  The only treatments I know are probably illegal in the EU and would render the leaves unusable in cooking.

I have closely inspected the few other plants that exist on the property and for now none of them seem to have an infestation.  Of course I don't want a breeding ground for these pests in my garden and potentially infecting my bulbs and other plantings.

Any suggestions are greatly appreciated. Thank you.

[Arnold]

Randy:

I've used a soap and water solution as my first attempt at controlling a pest.

If you can get a liquid Castillian soap that would  be perfect.

I use one ounce in a quart of water for a dilution.

It's the soap molecule that dissolves the waxy coating of many bugs that does them in.

Second shot would be Neem or a product called Spinosad which is an organic composed of a bacteria.


Arnold

[Diane Whitehead]

Yes, I use a cloth dipped in soapy water and rub the scale off the stems.

[Robert_Parks]

With a 10m tall tree, you've got some work to do if you can't use a systemic insecticide.

At the appropriate season for pruning a laurel, do a very heavy pruning to start restoration of a healthy shape, incinerate or landfill the trimmings through this whole process...try to protect new growth from infection. Control the (mostly) ants that transport the insects from place to place.

[Martin Bohnet]

Acetamiprid  is legal in the EU and does work - was my only chance to get rid of mealy bugs on a Drimia maritima. But with an edible tree I'd resort to a combination of pruning and soap water, too - maybe with a sip of ethyl alcohol to further assist in breaking down the wax barrier.

[Randy Linke]

Thank you for the suggestions.  I think a very heavy pruning is going to be in order, but I hate to think what it will look like based on some of the bad cuts on large limbs I see on the tree.  The main limbs are over 20cm in diameter.

I have been amazed that I have not seen a single ant on this tree.  The only ants I have seen on the property on the front walk area.  The ivy that I removed was infested with aphids, but I haven't seen them, ants or aphids, on other plants in the area.

Good to hear about Acetamiprid.  I had some Amaryillids with mealybugs and the systemic was the only thing that worked.

[Leo]

Your tree is too big, but I have many times eradicated mealybug infestations on smaller plants by submerging them in slightly soapy water for 8-12 hours. This drowns the eggs, too. I have used this on cacti, other succulents, leafy plants and various epiphytic orchids. I would not use it on a severely infested plant because there would be so many holes for soapy water to get into the plant tissues.