The foundation of a successful forestry block is good establishment. History has shown repeatedly that most crop failures occur in the first few years. They can be due to poor seedlings, poor plantings, poor stock control and any number of other reasons inside our outside a growers control. Any grower should avoid cutting corners at this stage.

Thirty years ago a 50% survival of young seedlings planted in the high country was considered acceptable. Today, there is no reason why 90% should not be achieved in anything other than the toughest season. The recipe for such success is simple:

Good planting stock (seedling) quality.

Proper handling between nursery bed and planting site.

Good establishment practices.

Seedling quality

New Zealand tree growers favour bare-rooted seedlings. Properly prepared bare-rooted seedlings will normally survive and grow significantly better than good containerised stock. They are also cheaper and easier to handle in bulk. This is true for broadleaf hardwoods as well as conifers. Root collar diameter is the best determinant of seedling quality. Target seedling dimensions for the major high country species are given in Table 1.

Seedling handling

Snow, frozen ground and spring farm commitments can mean considerable delay between seedling lifting in a lowland nursery (July/August) and planting at higher altitudes (September/October). Hence, proper storage and handling between the nursery and the planting site is particularly important. During this period seedlings must be kept cool, dormant and with moist root systems by proper packaging and cool-storage (at 1-3°C). Maximum cool-storage times are given in Table 1. Cool conditions must be maintained between removal from storage and actual planting.

Species	Age	Rootcollar diameter mm	Shoot Length	Cool Storage Weeks at 2°C
Corsican pine	2	8	20	10
Mountain pine	2-3	8	20-25	12
Ponderosa pine	2	10	25	10
Radiata pine	1	5	30	4
Douglas fir	2	10	45	6
European larch	2	10	50	8
Green alder	2	10	30	12
Mountain beech	3	6	60	1

Table 1 Recommended shoot lengths, minimum root collar diameters and maximum cool storage periods for bare rooted tree stocks for mountainland plantings.

Establishment

Site cultivation

Cultivation of the planting site aids seedlings by allowing roots to grow and access moisture and nutrients more readily. It can either be done mechanically before or during planting or by hand at time of planting.

Machine cultivation is essential on compacted soils or where soil pan exists.

Single line ripping with a winged ripper in summer or before soil gets too moist, to a depth of at least 60cm is the usual method. Ripping is becoming increasingly popular as it not only aids establishment but leads to easier and better quality planting. If ripping is not possible, extra time and effort is required at planting to ensure proper cultivation with the planting tool (usually a spade) to at least 20cm.

Planting

Planting is normally done in the late winter/early spring either by machine or by hand. If a machine is available the method has many advantages. No ripping is required although some machines have a ripping tyne mounted in front of the planting boot. A machine allows planting to be readily slotted into a busy spring farming schedule, there is no need to organise labour, food and accommodation. Costs are cheaper than hand planting, the quality is generally more consistent and planting rates are higher (600-1000 trees/hour for two people). There are large areas of the high country which are ideally suited for machine planting.

The normal hand planting tool is a specially constructed straight-bladed spade. Before planting, a 20cm square area should be cleared of competing vegetation with the planting spade. It is important to plant the seedling deep so that the soil level is 3-5cm above the root collar level. This increases seedling survival.

Fertilisers
Fertilisers are not generally recommended due to the likelihood that they will increase competition from weeds. There are two major exceptions. Eucalypts respond well to an application of nitrogen at planting. Urea (40g) or diammonium phosphate (80g) is placed away from immediate contact with the roots either at the bottom of the planting hole or in a slot 20cm out from the plant. Do not place fertilisers on or near the ground surface or weed competition will be encouraged. The second exception concerns boron, which is widely deficient in high country soils. The deficiency is corrected as a standard operation by application of 0.5g to 0.7g elemental boron per seedling (equivalent to 1 teaspoon of Ulexite) either at planting or anytime up to age 2. Slow release Ulexite is available from Canterbury Forestry Foundation. Borax is not recommended because it is too soluble.

Weed control
On improved or well vegetated country, weed control for the first two years is essential. On Hieracium infested soils with a high percentage of bare ground, weed control is less necessary, particularly if the ground has been cultivated by a ripper or a planting machine.

Weed control is most easily achieved by spraying a 1m² area around the seedling either before planting in the mid-autumn while weeds are actively growing or after planting over the top of seedlings with a selective herbicide (Table 2). Post-plant spraying should be done when soil temperatures are starting to rise, and not when seedlings are under stress or when they are actively growing.

Table 2. Chemical use guide for weed control

Pre plant Spray (Mar/Apr)	Species	Post plant Spray (Sept/Oct)
Use either: A For all species except poplars /willows Permazol SDA @ 22kg/ha in at least 400l water equiv. to (375g/15litre knapsack) or: B For poplars, willows or where twitch is dominant mix 16l Simazol SA and 6l Roundup/ha	Radiata pine Corsican pine Ponderosa pine Douglas fir Larch Leyland/Macrocarpa Cedars Oak, ash, elm etc before budburst Eucalypts Other species particularly legumes	C i) Grass/twitch or broadleaf weeds Velpar WPS 2kg/ha on light soils* 4kg/ha heavier soils or Velpar granules or Weed-a-metre @ 2kg/ha Use D (i), (ii) or (iii) Use D (i) or (ii) only Do not post plant spray	D i) Grasses only Gardoprim 500FW @ up to 20l/ha or ii) Twitch, cocksfoot, yellow fog dominant as for (i) but add Gallant at up to 5l/ha or iii) if broadleaf weeds dominant as for (i) but add Versatil at up to 5l/ha. (i), (ii) and (iii) can be mixed together

*Timing is critical, must be early in the season, if later use D.

Animal control
No tree planting should ever be attempted unless animal control has been achieved. Fencing should be standard practice to protect seedlings from domestic stock for at least the first 3-4 years. Animal reintroduction into young plantations should be done cautiously with regular checks for damage and immediate animal removal should significant browsing be observed.

It is often more difficult to prevent damage from smaller animals such as rabbits, hares and possums. Seedlings are attractive in the first few months due to higher nutrient levels from growth in the nursery.

Where populations are high, poisoning, shooting and trapping are the most effective control methods. Where animal numbers are low, repellents (mostly egg based) have been used successfully. to make 1 litre of repellent mix either 5 fresh eggs (well beaten) or 80g whole egg powder, and 100 mls of either acrylic resin or acrylic paint, with water. (Commercially available as "Treepel" from Aorangi Forestry Services, P. O. Box 6, Waimate, South Canterbury.)

Direct seeding
Tree seedlings can be established directly from seed either by broadcast seeding or by direct drilling using an agricultural drill. The main attraction of seeding is the low cost. The main disadvantage relative to planting is its unreliability.

Many factors influence success or failure and every season is likely to see a different result. Strikes can regularly range from being sufficiently poor to necessitate reseeding or planting, to being so good that considerable money must be spent on thinning. This is why, historically, direct seeding has very rarely replaced planting as a major establishment method.

Direct seeding trials are continuing in the high country and their outcome will determine exactly what role seeding deserves in future forest establishment operations.

Prepared by: Nick Ledgard, Forest Research Institute RANGIORA