It would be easy to assume that our naturally occurring native trees are so well suited to our environment that they should need very little care in order to complete their growth cycle and become majestic forest giants, just as did their forebears.
Unfortunately, things have radically changed over the last couple of hundred years, particularly the introduction of pests.
Without meaning to offend anyone, the most significant of all the pests are ...Humans. Initially, with their colonial mindset, armed with axes then eventually chainsaws, much of this country's wonderful forest cover was destroyed by people intent on making money. Logging the great Kauri forests for construction and export along with all the other species for boat building, furniture making etc, followed by the creation of farm pasture to produce livestock for food and profits. Early governments actually provided financial incentives to farmers for strip felling every single tree off their land.
Fortunately we have now woken up to the harm done, and it is now required to re-plant 20 metres on either side of waterways, and to re-plant steep slopes vulnerable to erosion. Not to mention raising the water tables, encouraging precipitation and providing oxygen for our grand children to breathe. Plus of course the natural beauty of our forests, far nicer to look at than the grass deserts created by farming.
Moving on ... those pesky humans in their great wisdom, have introduced huge numbers of other pests : Possums, Rabbits, Rats and mice, Stoats, Insect pests and more.
Most native species are initially threatened by rats and mice eating their seeds before they get a chance to germinate. No doubt the stoats and ferrets as well. Apart from the seeds and berries gathered by nurserymen from the trees as soon as they are ripe, the majority are quickly devoured by rodents. They were once confined to areas of human population, hanging about rubbish dumps and dark alleyways behind restaurants and bakeries. Unfortunately these things have been 'breeding like rabbits' for a couple of hundred years, and are now everywhere deep in the bush thriving on the seeds berries provided by our wonderful native trees, as well as stealing eggs and baby birds from their nests. It seems no matter where you go there are rats and mice, descendants of their forebears who have been 'jumping ship' since the days of Captain Cook.
Then it is the rabbits and possums. If a seed is fortunate enough to germinate in the wild, it is likely to become rabbit food before it has grown 5 centimetres. If it should escape the rabbits' attention and get a little taller, it will quickly be noticed and devoured by the possums. Those few that do get the chance to develop into a mature tree will definitely be grazed by possums and possibly eventually killed. It is said that an estimated 70 million of them chew their way through 21,000 tonnes of shoots, fruits, berries and leaves every night in NZ. (The equivalent of 190 million hamburgers per night)
There are many destructive insects out there, some of which are harder to trace back to their origins. Many have been inadvertently introduced through slack border controls, and others by human intent in order to attempt to control something else. Some perhaps lived here in smaller populations, but we have created a habitat in which they can now thrive.
The Leaf Miner that burrows through your cabbages will also attempt to wipe out your Kaka Beak trees. The Bronze Beetle will munch away at your Ti Toki and Pohutukawa.
I am not keen on adding to our pollution problems by pouring heavy chemicals on our trees, but fortunately, organic Neem Oil sprayed weekly will control most of the insect pests.
Leave me to deal with them here at the nursery stage. They are a constant battle, chewing their way through my seed trays stealing the seeds and berries as they sprout.
If you know they are active in your neighbourhood, use protective tree sleeves or wire netting when planting out the following : Puka, Kaka Beak, Kowhai, Karaka, Kauri, Puahou and Houpara (5 fingers), Lancewood, Ake Ake, Te Kouka (Cabbage trees). Once the trees are taller rabbits become less of a threat, but some trees will still be ring-barked by them.
There are poisons available, but they are dangerous to pets and children, and no matter how much you use, they will always just keep on coming. People often set gin traps for rabbits, but I wouldn't advise their use as they also catch pets and birds. They are very inhumane, seldom actually killing their victims and often severing a limb. You are likely to need to knock them on the head to finish them off. I have recently been surprised by finding a few in my Timms possum trap. Their huge numbers are rapidly multiplying here in the north, so at times of year they are in such heavy competition for food they will risk messing with a possum trap.
Traps and poison bait stations are the usual method of control. The Timms keyhole traps are generally best, as they make a quick kill and are easy to re-set, using a small piece of apple as bait. Cage traps work equally as well (baited with apple or a piece of carrot), but not so good for the squeamish as you will have to kill them yourself. (Bury them under the next tree you plant ... Karma at work !!!). Remember that they will also always keep on coming. The more we wipe them out the more they increase their breeding cycle. In the barren lands of Australia, the possum reduces it's breeding cycle down to only once every two years when there is little available to eat. Here in the lush New Zealand bush, they increase their breeding cycle to up to five times a year when there is an endless supply of food in front of them. As a Tree-grower and property owner, it will always be your duty to do your share of possum eradication for the sake of our country's future
As mentioned above Neem Oil sprayed weekly will control most insect pests. If you are into the heavy chemical mindset and aren't worried about your children's health, there are a range of nasty chemicals being produced and pushed by the destructive chemical corporations.
These trees are one of our most threatened by pests, beginning with slugs and snails at planting time. You can use the poison pellets, or preferably mulch with crushed shell which cuts into their underbellies and bleeds them out. You will need to refresh your shells from time to time or give them a good stir up if they develop a mulch cover. From Spring till Autumn, Kaka Beak are at risk of the leaf miner. Spray weekly with Neem Oil.
Protect from Rabbits at ground level. Stake well for the wind, and ideally provide some wind shelter, ideally surround them with wind-break cloth around four stakes in the ground around each tree, or a wind-break fence along their most exposed wind-ward side.
Dig the planting hole deep to encourage the anchor roots to go well down.
Same Slug and Snail issues as the Kaka Beak above, and vulnerable topowdery mildew while young. The leaves will develop a grey powdery coating that is easily treated with a regular spray of baking soda (One teaspoonful to a litre) dissolved in water with either a spraying oil or a liquid soap / paraffin oil mix. Protect from rabbits.
Spray weekly with Neem Oil if the new leaf growth is being chomped by insects. Protect from rabbits ... Trap the possums. A cage of wire-netting wrapped in wind-break will help to get these established.
These are likely to have their new leaf growth chomped by the bronze beetle every year, which won't kill them but does leave them looking untidy. Spray weekly with Neem Oil.
Te Kouka (Cabbage Tree)
Needs Rabbit protection, and is vulnerable to fungal disease which can be controlled with a copper spray a few times a year. Baking soda also works mixed with a spraying oil.
Much the same requirements for all natives : Dig a good hole that is 3 or 4 times the size of it's original pot. Width of hole is important here as the feeder roots will want to spread near the surface, while the deeper tap roots want to go down to seek water and anchor the tree.
Mix some compost in with your soil and add a couple of handfuls of Bio-Boost or Sheep pellets. Slow release pellets or tabs can be used to give the tree a head start for it's first year. If you are trapping possums and rabbits, bury one under each tree, but dig your hole deeper and place the body well below the roots.
Firmly pack the soil around the tree, but don't compact it too hard, too close to the roots.
Mulch well. Bush mulch is ideal, or use well rotted grass, sawdust and leaf compost, shredded bark, etc. If it is too fresh it will heat up and burn the stem, eventually ring-barking it. Leave a hollow immediately around the stem, but otherwise pile it on thick. This will help to keep the ground moist and as it rots down, allows the soil's natural organisms to thrive at surface level, providing food and nutrients to your tree. Add fresh layers regularly.
Water well as often as is necessary until the tree is well established. As long as you have mulched this won't be as vital, but in order to ensure survival watering is advised at least through the first summer until those roots are down deep enough to draw up some moisture.
A close-fitting tree-sleeve of plastic or metal is ideal for the first couple of years to get established, but not necessary if you build a complete protective cage around it : Hammer in four battens forming a 60 to 80 cm square around the tree. Attach fine mesh chicken wire, buried 10 cm into the ground. Add an outer layer of wind-break cloth.
Release by weeding from time to time, and mow in between your trees to avoid too much grass growth congestion. A weed-eater works best but is a risk of ring-barking if you have not used individual protection around each tree.
Set possum traps and re-bait regularly.
This depends on your location and desired effect. If you are seeking to display each individual tree's natural splendour, then you will space well apart and accept the need to mow between them for years. If however you are creating a bush restoration project, then you will plant as close as 1.5 metres apart and only need to mow for the first few years until a natural canopy has formed to shade over the grass.
In nature, many seedlings should germinate close together (That is Nature as it was before the pests arrived), and eventually compete with each other until only the strongest survive. By planting 1.5 metres apart (but no closer), you will quickly duplicate the visual wonder of a natural bush scene, especially by choosing a wide variety of foliage types. After 20 years or so, some will die back as they would in nature as those stronger specimens dominate, but also by now many new plants should have appeared at ground level as birds continue to drop seeds on the forest floor ... and of course you have been successfully killing off the pests. You shouldn't be worried about the inevitability of some dying off to the competition, as this is an eventual outcome, possibly years after your own departure from the scene.
Despite all the problems mentioned above, native trees still thrive in this country when properly cared for.
The ultimate Kiwi dream is to own a 'lifestyle block' and surround yourself with the natural beauty that is New Zealand.
Don't hesitate to go ahead with your dream and rescue an acreage of ex-farmland, returning it to it's natural splendour with a little hard work, followed by years of reward.