‘What is the tree with nice dark green leaves and pretty yellow flowers that grows all around here’ was a recent question from a customer. An easy answer for me, as I had just been looking at the huge number of these trees flowering everywhere this summer. These are Privet trees, (Ligustrum lucidum). There are two main types of Privet, the spring flowering white ones that grow to around 5m – they are the strongly scented ones that cause hayfever, and the yellow flowered ones that grow into big trees 10m+ tall that flower between January and March.

These trees are originally from China and were brought to New Zealand as a hedging plant. They are an ideal hedge – they grow in the damp, dry, shade, sun, frost, they trim well, the bees like the flowers and the birds like the berries.

And here lies the problem. They grow in all the same places as our native trees do, the native birds like the seeds, and they are a wonderful food source for Keruru in the winter. The native birds eat the berries and spread the Privet seed all around the district, including amongst the native forest. Because the Privet seedlings can germinate and grow in low light conditions, they will grow alongside native trees, and being stronger and more vigorous, they will push their way up through the canopy and dominate the natives.

Why is this a problem? After all, isn’t it great that they provide food for the native birds? The reason that privet trees are a big problem throughout NZ is that they create dense thickets and smother out our native trees. There are older settled areas in NZ (the Thames area being a good example), where there are whole hillsides of Privet trees growing where there would normally have been natives. If there is only one variety of trees, the native birds won’t have food all year round like they would normally have in the native forest.

So, what can be done? We on our own property have started a crusade against Privet trees. We have found sawing the tree near the base and spraying a 50% Glyphosate 50% water solution on the stump using a spray bottle works well. You can also drill holes in the truck or stump by drilling 10cm deep holes in the trunk or stump using a 15mmm or 20mm drill bit. Do these holes around 25-30cm apart, and pour a salt solution into the holes – use a 2:1 ratio of water and salt, or pour undiluted glyphosate into the holes using a funnel, syringe or drench gun.

Look out for seedlings under the older trees. We found hundreds of seedling trees waiting to take the place of the big ones we killed.

Then, plant native trees as an alternative. Puriri trees are a great option in frost free areas, as they have flowers and berries on almost all year. Other native options with berries to help feed the birds are Coprosma, Mahoe. Pittosporum, Titoki, Cabbage tree, Pigeonwood.

If everyone on their own properties removed the privet growing in their native areas and roadsides it would be a huge step in the right direction to reduce the number of Privet in the district. Unfortunately we are never likely to irradicate them, but if we can keep them from dominating the native forest that would be a great start.