Question by Tony B.
Hi there,
We had a 5m tall lilly pilly hedge cut down to 1.5m stumps in early 2020. It had a severe case of psyllids with mould and ants. We feed the trees and got new growth, however after a 2 month period over summer, while we were away, the psyllids came back and hammered the new growth and the mould followed. As it was extensive, I have just cut all of the new growth off and am going to restart. Can you recommend a regime to really keep the pests at bay and get the hedge healthy again.
The hedges get full sunlight and are well established with a trunk diameter of 20-30cm. The roots are under a driveway to one side and a deck on the other with about a 1m strip that they are planted in.
I am looking to compost then mulch over the strip this weekend. And try and keep the ants away with ant sand as I believe they ‘farm’ the psyllids to get the sugary deposits.
Sarah's answer
Hi Toby,
You are right about the ants being related to the psyllid problem as ants encourage sap suckers to stay so they can farm them for their honeydew. The honeydew is what is causing the sooty mould. So, by addressing the psyllid, the ant and mould problem should go away although the ant sand will help the situation.
As for the psyllid, they can establish quickly in weak or stressed plants so make sure the hedge is well watered and feed the trees regularly with an appropriate plant food. The compost and mulch will be a good help as that will help keep temperatures and moisture levels even. Consider running irrigation along the hedge, so watering is consistent.
Monitor the new growth for signs of trouble and treat immediately as psyllid populations can quickly get out of control. You can thoroughly spray with an oil-based insecticide that can smother the insects especially under the leaves. This will need to be repeated as per the instructions on the packet until you break the life cycle. You may need a stronger insecticide if the populations prove to be a bit stubborn. Inspect the hedge often in case they come back in the future.
And finally make sure you clear away any trimming and debris, especially affected leaves from under the hedge and throw away or burn.
I hope this helps and you can bring your hedge back to full vigour.
Cheers Sarah : o)
